WO2025163036A1

WO2025163036A1 - Water treatment system and method

Info

Publication number: WO2025163036A1
Application number: PCT/EP2025/052342
Authority: WO
Inventors: Marijn TIMMER; Tim VAN WINCKEL; Siegfried VLAEMINCK
Original assignee: Universiteit Antwerpen
Current assignee: Universiteit Antwerpen
Priority date: 2024-01-30
Filing date: 2025-01-30
Publication date: 2025-08-07
Anticipated expiration: 2026-07-30

Abstract

The present invention relates to a water treatment system and method, in particular a wastewater treatment system and method. The water treatment system combines the use of aeration membranes and filtration membranes which are periodically scoured, depending on the oxidative status of the water.

Description

WATER TREATMENT SYSTEM AND METHOD

FIELD OF THE INVENTION

The invention relates to the field of environmental engineering, in particular to water purification.

BACKGROUND OF THE INVENTION

Water scarcity is increasing throughout the world. Conventional treatment is not efficient due to its high space demands, energy requirements and unsuitability to reuse treated water. More specifically, conventional settlers present a means for slow and imperfect separation of water and suspended solids, and conventional aerators are not energy efficient. On the other hand, a clever application of membranes offers an enormous potential to intensify treatment while facilitating water reuse.

It is an objective of the present invention to address the above-mentioned shortcomings.

SUMMARY OF THE INVENTION

The present invention relates to a dual membrane system for membrane aeration and membrane filtration of water, in particular wastewater, such as sewage, black water, grey water, and/or wastewater from industry and/or agriculture. Accordingly, the invention relates to a water treatment, purification, and/or filtration system comprising one or more aeration membrane and one or more filtration membrane. The invention further relates to a water treatment, purification, and/or filtration method, using the water treatment, purification, and/or filtration system of the invention as described herein.

The present inventors realized that the combination of aeration membranes and filtration membranes in water treatment, purification, and/or filtration beneficially affects both the ecological footprint as well as energy and operational costs, while maintaining high treatment, purification, and filtration rates.

Purification of wastewater may typically involve the use of microorganisms (i.e. biomass), such as bacteria, in particular aerobic bacteria, to convert, such as to oxidize contaminants in water, such as organic or inorganic materials, particulates, etc., typically resulting among others in an increase of biomass and production of gaseous components. In this way, water contamination is reduced. Efficient water treatment involving biomass is however critically dependent on oxygen supply.

In this context, the combination of aeration membranes and filtration membranes according to the present invention is beneficial in multiple ways compared to the state of the art. The inventors found that in particular oxygenation - and hence overall performance - can be optimized according to the present invention. Firstly, membrane aeration is more energyefficient than bubble aeration (such that aeration energy input can be reduced). Moreover, the attachment on the aeration membrane will make the broth effectively clearer, and therefore easier to filter (such that filtration energy input can be reduced). Finally, due to the biofilm nature of the attached growth, the sludge (containing detached and partially disintegrated biofilm material) will consist of bigger particles, and therefore sludge settleability will be better (easier wasting).

However, the inventors found that biomass management is critical to manage oxygen transfer from the membrane to the liquid. They have determined that an active removal of the biofilm from the aeration membrane can allow more efficient management thereof. Accordingly, they have developed a dedicated strategy to optimize sludge management so as to minimize energy requirement and maximise effluent water quality. More particularly, the inventors found that operation of the system of the present invention based on the oxidative status of the water has incremental benefits on overall footprint and energy and management costs. In particular, the inventors found that the oxidative status of the water which is treated, purified, and/or filtered has a strong influence on the level of attachment of biomass to the membranes. They have observed that the oxidative status of the water which is treated, purified, and/or filtered vastly impacts biofilm formation, stability, and quality. For instance, the inventors observed that low dissolved oxygen in the bulk liquid (indicative of anoxic or anaerobic conditions) promotes attachment of bacteria to the membranes, in particular aeration membranes, and hence biofilm formation (bacteria compete for oxygen at the membrane surface). As a result, biofilms tend to become more dense. This has two important consequences. On the one hand, gas transfer efficiency decreases, and in particular aeration energy requirements increase. On the other hand, compact biofilms are harder to remove (e.g. through scouring) from the membranes, such that overall biomass removal efficiency is reduced. The inventors have found that the oxygen status of the water can be used as a proxy for biofilm status, including formation, stability, and quality. Accordingly, membrane scouring can be tailored depending on the oxygen status in order to maintain optimal biofilm status, including formation, stability, and quality and hence optimal overall water treatment, purification, and/or filtration efficiency. According to the invention, the combination of membrane aeration and filtration including the oxidative status-based scouring regime can reach higher energy efficiency, contaminant removal rates, and filterability (and hence transmembrane flux) for same or better-quality effluent production. Moreover, performance can be achieved that effectively regulates the solids residence time (SRT), whilst minimizing exposure of the filtration membrane to the (biofouling) biomass. Indeed, during the scouring phase, a fraction of the biomass is scoured off the aeration (and filtration) membranes, where it grows in biofilms. This fraction: the flocfraction allows for wasting, such as to control SRT and minimizes respirative oxygen demand.

The inventors further found that more cost effective and superior water treatment, not only in terms of effectivity but also in terms of maintenance requirements and durability, can be achieved with a method and system of the invention. In particular, water treatment process control of the invention is instrumental. Timing, frequency, and duration of process characteristics, including membrane scouring and wasting can advantageously be optimized as described herein. In addition to oxidative status, additional parameters, in particular suspended solids content associated parameters can be tailored to streamline and optimize the water treatment process. This integrative approach allows to optimally align all components and subprocesses of the water treatment system of the invention, including biofilm formation, maintenance, detachment, and re-attachment in combination with scouring and wasting frequency and duration as well as aeration and filtration control, including recirculation.

In a first aspect, the present invention relates to a water treatment, purification, and/or filtration system comprising:

(a) a first module comprising one or more aeration membrane(s);

(b) a second module in fluid connection with said first module, and comprising one or more filtration membrane;

(c) one or more means for scouring said one or more aeration membrane and optionally means for scouring said one or more filtration membrane;

(d) means for determining the oxidative status of water; wherein said means for scouring said one or more aeration membrane and optionally said means for scouring said one or more filtration membrane are configured to be operated based on the oxidative status of said water.

In a related aspect, the present invention relates to a water treatment, purification, and/or filtration system comprising:

(a) a first module comprising one or more aeration membrane(s); (b) a second module in fluid connection with said first module, and comprising one or more filtration membrane;

(c) one or more means for scouring said one or more aeration membrane and means for scouring said one or more filtration membrane;

(d) means for determining the oxidative status of water; wherein said means for scouring said one or more aeration membrane and said means for scouring said one or more filtration membrane are configured to be operated based on the oxidative status of said water.

In a related aspect, the invention relates to a method of water treatment, purification, and/or filtration, comprising, in a water treatment, purification, and/or filtration system, such as according to the various aspects described herein, aerating water through the one or more aeration membrane and filtering the water through the one or more filtration membrane; wherein, when a predetermined oxidative status threshold of the water is achieved (in the water treatment, purification, and/or filtration system), the one or more aeration membrane and optionally the one or more filtration membrane are scoured.

The appended claims are explicitly incorporated herein by reference.

The present invention is in particular captured by any one or any combination of one or more of the below numbered statements 1 to 63, with any other statement and/or embodiments.

1 . A water treatment, purification, and/or filtration system comprising

(a) a first module comprising one or more aeration membrane;

(d) means for determining the oxidative status of water;

(e) means for extracting suspended particulate material; wherein said means for scouring said one or more aeration membrane and optionally said means for scouring said one or more filtration membrane are configured to be operated based on the oxidative status of said water.

2. The water treatment, purification, and/or filtration system according to statement 1 , wherein said means for determining the oxidative status of water comprise an oxidationreduction potential (ORP) sensor, a dissolved oxygen (DO) sensor, and/or a nitrate and/or nitrite sensor. 3. The water treatment, purification, and/or filtration system according to any of statements 1 to 2, wherein said one or more aeration membrane comprises one or more hollow fiber membrane or one or more flat plate membrane.

4. The water treatment, purification, and/or filtration system according to any of statements 1 to 3, wherein said one or more aeration membrane comprises a biofilm.

5. The water treatment, purification, and/or filtration system according to any of statements 1 to 4, wherein said first module comprises a membrane-aerated biofilm reactor (MABR).

6. The water treatment, purification, and/or filtration system according to any of statements 1 to 5, wherein said one or more filtration membrane comprises one or more flat plate inner permeate channel (I PC) membrane.

7. The water treatment, purification, and/or filtration system according to any of statements 1 to 6, wherein said one or more filtration membrane comprises one or more microfiltration membrane and/or one or more ultrafiltration membrane.

8. The water treatment, purification, and/or filtration system according to any of statements 1 to 7, wherein said second module comprises a membrane bioreactor (MBR).

9. The water treatment, purification, and/or filtration system according to any of statements 1 to 8, wherein said first module and said second module are configured to allow water to recirculate (for instance in a closed loop) between said first module and said second module.

10. The water treatment, purification, and/or filtration system according to any of statements 1 to 9, wherein said means for scouring said one or more aeration membrane and optionally said means for scouring said one or more filtration membrane are configured to be active upon reaching a predetermined oxidative status threshold of the water.

11. The water treatment, purification, and/or filtration system according to any of statements 1 to 10, wherein said means for scouring said one or more aeration membrane and optionally said means for scouring said one or more filtration membrane are configured to be inactive as long as a predetermined oxidative status threshold of said water is not reached.

12. The water treatment, purification, and/or filtration system according to statement 10 or 11 , wherein said predetermined oxidative status threshold is dynamically adapted based on the average time to reach a predetermined suspended particulate material concentration after initiation of one or more previous scouring events.

13. The water treatment, purification, and/or filtration system according to any of statements 1 to 12, wherein said means for scouring said one or more aeration membrane and optionally said one or more filtration membrane are configured to be active at least until a predetermined suspended particulate material concentration is reached. 14. The water treatment, purification, and/or filtration system according to statement 13, wherein said predetermined suspended particulate material concentration is dynamically adapted based on the average maximum suspended particulate material concentration during or after one or more previous scouring events.

15. The water treatment, purification, and/or filtration system according to any of statements 1 to 14, wherein said means for scouring said one or more aeration membrane and optionally said one or more filtration membrane are configured to be activated if a predetermined suspended particulate material concentration reduction (i.e. decrease) is not reached during a predetermined time frame after a previous scouring event.

16. The water treatment, purification, and/or filtration system according to statement 15, wherein said predetermined suspended particulate material concentration reduction is dynamically adapted based on the average maximum suspended particulate material concentration during or after one or more previous scouring events.

17. The water treatment, purification, and/or filtration system according to any of statements 1 to 16, wherein said means for scouring said one or more aeration membrane and optionally said one or more filtration membrane are configured to be activated if a predetermined suspended particulate material concentration increase is not reached during a predetermined time frame after initiation of a previous scouring event.

18. The water treatment, purification, and/or filtration system according to statement 17, wherein said predetermined suspended particulate material concentration increase is dynamically adapted based on the average maximum suspended particulate material concentration during or after one or more previous scouring events.

19. The water treatment, purification, and/or filtration system according to any of statements 1 to 18, wherein said means for scouring said one or more aeration membrane and optionally said one or more filtration membrane are configured to be activated for a predetermined amount of time, or wherein said means for scouring said one or more one or more filtration membrane are configured to be activated continuously.

20. The water treatment, purification, and/or filtration system according to any of statements 1 to 19, wherein said means for scouring said one or more aeration membrane and optionally said means for scouring said one or more filtration membrane are configured to be activated for a time ranging from 1 minute to 10 minutes, preferably ranging from 2 minutes to 8 minutes, such as for 5 minutes.

21. The water treatment, purification, and/or filtration system according to any of statements 1 to 20, wherein said means for scouring said one or more aeration membrane and optionally said means for scouring said one or more filtration membrane are configured to be active if oxidation-reduction potential (ORP) of said water is at most +50 mV, preferably at most +10 mV, more preferably at most 0 mV, such as at most -10 mV or at most -50 mV, or at most -200 mV, preferably as determined with an Ag/AgCI reference electrode with an electrolyte solution of 4M KCI.

22. The water treatment, purification, and/or filtration system according to any of statements 1 to 21 , wherein said means for scouring said one or more aeration membrane and said means for scouring said one or more filtration membrane are means for air scouring.

23. The water treatment system according to any of statements 1 to 22, further comprising means to determine the suspended particulate material concentration of water.

24. The water treatment, purification, and/or filtration system according to statement 23, wherein said means to determine the suspended particulate material such as floc concentration of water comprise a total suspended solids (TSS) sensor, a turbidity sensor, or an optical density sensor.

25. The water treatment, purification, and/or filtration system according to any of statements 1 to 24, further comprising means to determine the pH of water.

26. The water treatment, purification, and/or filtration system according to any of statements 1 to 25, wherein said particulate material comprises floc and/or biomass.

27. The water treatment, purification, and/or filtration system according to any of statements 1 to 26, further comprising a water to be treated influent conduit and a treated water effluent conduit.

28. The water treatment, purification, and/or filtration system according to any of statements 1 to 27, further comprising aerobic microorganisms and/or anaerobic microorganisms.

29. The water treatment, purification, and/or filtration system according to any of statements 1 to 28, further comprising one or more pump, compressor, and/or blower.

30. The water treatment, purification, and/or filtration system according to any of statements 1 to 29, comprising a circulation pump, configured to effect circulation of water between the one or more aeration membrane and the one or more filtration membrane.

31. The water treatment, purification, and/or filtration system according to any of statements 1 to 30, comprising one or more scouring compressor or blower, configured to effect scouring of the one or more aeration membrane and the one or more filtration membrane.

32. The water treatment, purification, and/or filtration system according to any of statements 1 to 31 , comprising a wasting pump, configured to remove suspended particulate material, in particular floc from the water treatment system.

33. The water treatment, purification, and/or filtration system according to any of statements 1 to 32, comprising an extraction pump, configured to remove treated water from the water treatment system (through the one or more filtration membrane(s)). 34. The water treatment, purification, and/or filtration system according to any of statements 1 to 33, comprising an influent pump, configured to introduce water to be treated in the water treatment system.

35. The water treatment, purification, and/or filtration system according to any of statements 1 to 34, comprising an aeration compressor or blower, configured to effect aeration of the water through the one or more aeration membrane.

36. The water treatment, purification, and/or filtration system according to any of statements 1 to 35, wherein said water is wastewater, such as wastewater that did or did not undergo one or more prior treatment steps.

37. The water treatment, purification, and/or filtration system according to any of statements 1 to 36, the prior treatment of the water comprises one or more physical, chemical and/or biological processes, such as anaerobic digestion.

38. The water treatment, purification, and/or filtration system according to any of statements 1 to 37, wherein said water is grey water, black water and/or yellow water, and/or wastewater from household, office, and/or industrial or agricultural activities, including centralized sewage or domestic sewage.

39. The water treatment, purification, and/or filtration system according to any of statements 1 to 38, configured to aerate water through at least the one or more aeration membrane and filter water through the one or more filtration membrane; wherein the one or more aeration membrane and optionally the one or more filtration membrane are configured to be scoured upon reaching a predetermined oxidative status threshold of the water, resulting in the water containing suspended particulate material, such as floc.

40. The water treatment, purification, and/or filtration system according to statement 39, configured to remove at least part of the suspended particulate material, such as floc, if the suspended particulate material, such as floc, concentration exceeds a predetermined suspended particulate material, such as floc, concentration threshold.

41. The water treatment, purification, and/or filtration system according to statement 40, wherein said predetermined suspended particulate material concentration is dynamically adapted based on the average maximum suspended particulate material concentration during or after one or more previous scouring events.

42. The water treatment, purification, and/or filtration system according to statement 40, wherein said predetermined suspended particulate material concentration is dynamically adapted based on a preset solids residence time (SRT).

43. The water treatment, purification, and/or filtration system according to any of statements 1 to 42, configured to remove at least part of the particulate material, such as floc during and/or after scouring the one or more aeration membrane and optionally the one or more filtration membrane. 44. The water treatment, purification, and/or filtration system according to any of statements 1 to 43, configured to remove at least part of the particulate material, such as floc until a threshold oxidative status in said water is reached.

45. The water treatment, purification, and/or filtration system according to any of statements 1 to 44, configured to remove at least part of the particulate material, such as floc until a threshold particulate material, such as floc content in said water is reached or until a threshold particulate material, such as floc content reduction in said water is reached.

46. The water treatment, purification, and/or filtration system according to any of statements 1 to 45, wherein aeration is done by air, oxygen-enriched air, or oxygen.

47. The water treatment, purification, and/or filtration system according to any of statements 1 to 46, further comprising means for bubble aeration.

48. A method of water treatment, purification, and/or filtration, comprising in a water treatment, purification, and/or filtration system according to any of statements 1 to 47 aerating water through the one or more aeration membrane and filtering the water through the one or more filtration membrane; wherein when a first predetermined oxidative status threshold of the water is achieved the one or more aeration membrane and optionally the one or more filtration membrane are scoured, preferably only the one or more aeration membrane is scoured.

49. The method according to statement 48, wherein said one or more aeration membrane and optionally the one or more filtration membrane are scoured until a second predetermined oxidative status is reached.

50. The method according to statement 48, wherein said one or more aeration membrane and optionally the one or more filtration membrane are scoured until a predetermined suspended particulate material concentration is reached.

51 . The method according to any of statements 48 to 50, wherein said first and/or second predetermined oxidative status threshold is dynamically adapted based on the average time to reach a predetermined suspended particulate material concentration after initiation of one or more previous scouring events.

52. The method according to statement 50 or 51 , wherein said predetermined suspended particulate material concentration is dynamically adapted based on the average maximum suspended particulate material concentration during or after one or more previous scouring events.

53. The method according to any of statements 48 to 52, wherein said one or more aeration membrane and optionally said one or more filtration membrane are scoured if a predetermined suspended particulate material concentration reduction is not reached during a predetermined time frame after a previous scouring event.

54. The method according to statement 53, wherein said predetermined suspended particulate material concentration reduction is dynamically adapted based on the average maximum suspended particulate material concentration during or after one or more previous scouring events.

55. The method according to any of statements 48 to 54, wherein said means for scouring said one or more aeration membrane and optionally said one or more filtration membrane are configured to be activated if a predetermined suspended particulate material concentration increase is not reached during a predetermined time frame after initiation of a previous scouring event.

56. The method according to statement 55, wherein said predetermined suspended particulate material concentration increase is dynamically adapted based on the average maximum suspended particulate material concentration during or after one or more previous scouring events.

57. The method according to any of statements 48 to 56, further comprising removing at least part of the suspended particulate material, such as floc, obtained after scouring.

58. The method according to statement 57, configured to remove at least part of the suspended particulate material, such as floc, if the suspended particulate material, such as floc, concentration exceeds a predetermined suspended particulate material, such as floc, concentration threshold.

59. The method according to statement 57 or 58, wherein said predetermined suspended particulate material concentration is dynamically adapted based on the average maximum suspended particulate material concentration during or after one or more previous scouring events.

60. The method according to statement 57 or 58, wherein said predetermined suspended particulate material concentration is dynamically adapted based on a preset solids residence time (SRT).

61. The method according to any of statements 48 to 60, wherein the oxidative status of said water is periodically or continuously measured.

62. The method according to any of statements 48 to 61 , wherein the rate of influent water approximates or is equal to the rate of effluent water.

63. The method according to any of statements 48 to 62, wherein during scouring recirculation of the water in the system is prevented or interrupted and/or filtration is prevented or interrupted.

DESCRIPTION OF THE DRAWINGS

Figure 1 : Schematic of a water treatment system according to an embodiment of the invention wherein the first and second module are respectively in separate housings (A) or in the same housing (B). wherein (1) water treatment system; (2) first module; (3) aeration membrane(s) (depicted are exemplary hollow fiber membranes); (4)second module; (5) filtration membrane(s); (6) fluid connection; (7) means for scouring the aeration membrane(s); (8) means for scouring the filtration membrane(s); (9) means for determining the oxidative status; (10) means for determining the solids content; (11) means for determining the pH; (12) means for extracting/wasting solids and/or biomass; (13) influent conduit; (14) effluent conduit; (15) circulation pump; (16) scouring compressor/blower; (17) solid waste extraction/wasting pump; (18) effluent (i.e. treated water) pump; (19) influent (i.e. waterto be treated) pump; (20) aeration compressor/blower; (21) controller.

Figure 2: Schematic of a water treatment system according to an embodiment of the invention. Figure 3: Schematic operation of a water treatment system according to an embodiment of the invention.

Figure 4: (A) Water treatment system according to an embodiment of the invention. A: vessel for effluent; B: wasting pump; C: filtration membrane; D: heating bath ; E: scouring pump filtration membrane; F: recirculation pump filtration membrane; G: wasting vessel; H: aeration membrane; I: headspace and level control; J: external loop with flow cell for DO, pH, & ORP sensor, and sampling port; K: recirculation pump; L: DO-controller; M: overflow vessel; N: membrane extraction pump (FW/BW); O: scouring pump; P: pH and ORP controller; Q: wasting timer; R: influent pump; S: Scouring pump aeration membrane; T: Computer for logging and microcontroller control. (B) Water treatment system according to an embodiment of the invention. A: wasting pump; B: filtration membrane (MBR) with scouring device below; C: return pump for MBR effluent; D: recirculation pump from MBR to MABR; E: heating bath; F: headspace and level detection; G: connection from MABR to MBR; H: waste vessel; I: MABR headspace; J: aeration membrane; K: heating coil; L: DO-controller (connected to Arduino); M: effluent vessel; N: membrane extraction pump (FW/BW); O: MABR recirculation pump; P: external loop with flow cell for DO, pH, ORP, and TSS sensors, and sampling port; Q: pH and ORP controller (connected to Arduino); R: flow meters for scouring (MBR), MABR, and membrane aeration (connected to a pressurized air circuit); S: Arduino microcomputer; T: TSS controller (connected to Arduino); II: computer for logging and Arduino control; V: influent pump; W: fridge containing stirred influent.

Figure 5: Flowchart of operation of an embodiment of a water treatment system of the invention. The star(*) marks a potential suspended solids or time based control mechanism.

Figure 6: Setpoint adaptation strategy according to an embodiment to steer the suspended solids profile in the reactor towards the desired one.

Figure 7: Correlation between volatile suspended solids (VSS) (as a measure of detached sludge/biofilm after scouring) and oxidation-reduction potential (ORP).

Figure 8: Suspended solids re-attachment after scouring in function of time, concentration, and reaction conditions. Figure 9: Correlation between the oxidation-reduction potential (ORP) and water quality (measured as chemical oxygen demand; COD) in the effluent (A) or inside the water treatment system (B).

Figure 10: Correlation between oxidation-reduction potential (ORP) and the water quality (measured as chemical oxygen demand; COD) ratio between inside the water treatment system and the effluent.

Figure 11 : Example of a TSS profile in the MABR-MBR during a scouring event at t=0 and performance indicators that can be deduced from measured the TSS profile in th coming 30 minutes.

DETAILED DESCRIPTION OF THE INVENTION

Before the aspects and embodiments of the present invention are described, it is to be understood that this invention is not limited to particular systems and methods or combinations described, since such systems and methods and combinations may, of course, vary. It is also to be understood that the terminology used herein is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

As used herein, the singular forms “a”, “an”, and “the” include both singular and plural referents unless the context clearly dictates otherwise.

The terms “comprising”, “comprises” and “comprised of” as used herein are synonymous with “including”, “includes” or “containing”, “contains”, and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. It will be appreciated that the terms “comprising”, “comprises” and “comprised of” as used herein comprise the terms “consisting of”, “consists of” and “consists of”, as well as the terms “consisting essentially of”, “consists essentially” and “consists essentially of”.

The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within the respective ranges, as well as the recited endpoints.

The term “about” or “approximately” as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of +/-20% or less, preferably +/-10% or less, more preferably +/-5% or less, and still more preferably +/-1 % or less of and from the specified value, insofar such variations are appropriate to perform in the disclosed invention. It is to be understood that the value to which the modifier “about” or “approximately” refers is itself also specifically, and preferably, disclosed. Whereas the terms “one or more” or “at least one”, such as one or more or at least one member(s) of a group of members, is clear per se, by means of further exemplification, the term encompasses inter alia a reference to any one of said members, or to any two or more of said members, such as, e.g., any >3, >4, >5, >6 or >7 etc. of said members, and up to all said members.

All references cited in the present specification are hereby incorporated by reference in their entirety. In particular, the teachings of all references herein specifically referred to are incorporated by reference.

Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.

In the following passages, different aspects of the invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some, but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the appended claims, any of the claimed embodiments can be used in any combination.

In the following detailed description of the invention, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration only of specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilised, and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

Preferred statements (features) and embodiments of this invention are set herein below.

With reference to Figure 1 , the following components may be present in the water treatment system according to the invention.

1 . water treatment system

2. first module

3. aeration membrane(s) (depicted are exemplary hollow fiber membranes)

4. second module

5. filtration membrane(s)

6. fluid connection

7. means for scouring the aeration membrane(s)

8. means for scouring the filtration membrane(s)

9. means for determining the oxidative status

10. means for determining the solids content

11. means for determining the pH

12. means for extracting/wasting solids and/or biomass

13. influent conduit

14. effluent conduit

15. (re)circulation pump

16. scouring compressor/blower

17. solid waste extraction/wasting pump

18. effluent (i.e. treated water) pump

19. influent (i.e. water to be treated) pump

20. aeration compressor/blower

21. controller

Further components which may be present in certain embodiments of the water treatment system of the invention are detailed in Figure 4.

In an aspect, the invention relates to a water treatment system comprising (a) a first module comprising one or more aeration membrane; (b) a second module in fluid connection with said first module, and comprising one or more filtration membrane;

(c) means for scouring said one or more aeration membrane and optionally means for scouring said one or more filtration membrane;

In a related aspect, the invention relates to a water treatment system comprising

(a) a first module comprising one or more aeration membrane;

(c) means for scouring said one or more aeration membrane and means for scouring said one or more filtration membrane;

The water treatment system of the invention is particularly suited for treatment of wastewater. Accordingly, the water treatment system of the invention may equally be considered as a wastewater treatment system. As used herein, the term “wastewater” has its ordinary meaning in the art. By means of further guidance, and without limitation, wastewater refers to any water that has been contaminated by human activities and is no longer suitable for its original purpose. It includes water from households, businesses, industries, and agricultural activities that has been used for various purposes and contains impurities, pollutants, or other substances. Wastewater can come from sources such as toilets, showers, sinks, washing machines, and industrial and agricultural processes. Wastewater typically contains a variety of pollutants, including organic and inorganic substances, chemicals, pathogens, and suspended solids. The water to be treated according to the invention may or may not have undergone prior treatment before being treated in by the system of the invention. Prior treatment may for instance include removal of larger debris or objects (e.g. through screening) or primary treatment such as settling to remove heavier solids or to remove oils or greases.

In certain embodiments, the water to be treated is municipal or household wastewater (sewage). In certain embodiments, the water to be treated is industrial wastewater. In certain embodiments, the water to be treated is a combination of municipal wastewater and industrial wastewater. The terms “municipal wastewater and “industrial wastewater” have their ordinary meaning in the art. By means of further guidance, and without limitation, household wastewater refers to the wastewater generated from domestic activities within a household. It includes all the used water from various sources within a home, such as bathroom fixtures (i.e. water from showers, bathtubs, sinks, and bidets; this water is often referred to as grey water), toilets (i.e. water flushed down the toilet; this is considered black water and is highly contaminated), kitchen (i.e. water from sinks used for washing dishes, vegetables, and fruits, and from dishwashers; it can contain food particles and grease), laundry (i.e. water from washing machines used for cleaning clothes and linens), or water from other household activities, such as cleaning floors or washing pets. Household wastewater can contain a variety of pollutants, including organic matter, chemicals, microbes, soap, and food particles. By means of further guidance, and without limitation, industrial wastewater refers to water that has been used in industrial processes and contains various pollutants and contaminants as a result of those processes. Industrial wastewater can originate from a wide range of industries, including manufacturing, chemical production, mining, food processing and production, pharmaceuticals, textiles, and many others. The specific composition of industrial wastewater depends on the industry producing it. Common pollutants found in industrial wastewater include organics, inorganics, heavy metals, chemicals, solvents, oils, grease, suspended solids, and toxic substances. It will be understood that wastewater originating from for instance office activities may also be included (and may typically be classified similar as household wastewater or (less often) industrial wastewater, depending on the office activities involved).

In certain embodiments, the water to be treated is grey water. In certain embodiments, the water to be treated is black water. In certain embodiments, the water to be treated is a combination of grey water and black water. The terms “grey water” and “black water” have their ordinary meaning in the art. By means of further guidance, and without limitation, grey water refers to relatively clean household wastewater that comes from non-toilet fixtures such as sinks, showers, bathtubs, and washing machines. It does not contain faecal matter, but it may contain traces of soap, detergent, grease, and food particles. By means of further guidance, and without limitation, black water refers to highly contaminated wastewater that comes from toilets and urinals. It contains faeces, urine, toilet paper, and potentially harmful microorganisms and chemicals.

The (waste)water treatment system of the invention essentially purifies the water to a certain extent. Accordingly, the (waste)water treatment system of the invention may equally be considered a (waste)water purification system. Similarly, the (waste)water treatment system of the invention essentially filters the water to a certain extent. Accordingly, the (waste)water treatment system of the invention may equally be considered a (waste)water filtration system.

The (waste)water treatment, purification, and/or filtration system of the invention typically involves biological (waste)water treatment, purification and/or filtration. Accordingly, the (waste)water treatment, purification, and/or filtration system of the invention may equally be considered a biological (waste)water treatment, purification, and/or filtration system.

As used herein, the term “biological (waste)water treatment” has its ordinary meaning in the art. By means of further guidance, and without limitation, (micro)biological (waste)water treatment refers to a process that utilizes microorganisms (such as in particular bacteria) to break down organic and inorganic pollutants in (waste)water. The microorganisms may be naturally present in the (waste)water or may (possibly in addition to already being present to a certain extent) be added to the (waste)water. Where microorganisms are already present in the water, the same or different microorganisms may be added. In particular embodiments, microorganisms specifically adapted for removal of specific pollutants may be added. In particular, during or upon startup of the water treatment system of the invention, microorganisms may be added, whereas preferably, during steady state operation, no additional microorganisms are added anymore. Typically, biological (waste)water treatment involves aeration, which is required to provide sufficient oxygen to the microorganisms in order to effectively allow pollutant breakdown, digestion, fermentation, or otherwise removal, conversion, or consumption of pollutants. Aeration according to the present invention is achieved by aeration membranes, as described herein elsewhere.

Essentially, biological (waste)water treatment typically results in an increase of biomass as a result of microbial pollutant breakdown, digestion, fermentation, or otherwise removal, conversion, or consumption of pollutants. Typically, gaseous or volatile components such as CO2 and/or N2 are also produced. As used herein, unless explicitly indicated otherwise, the term “biomass” refers to the sum of microbial biomass, i.e. the total mass of microorganisms, and any other particulate matter in the water. As used herein, the term “particulate material” refers to suspended solids, such as total suspended solids (TSS) and may for instance include volatile suspended solids (VSS), i.e. the organic fraction of suspended solids. When referring to a percentage of suspended particulate material or suspended solids it will be understood that such percentage preferably is wt/wt% or w/v%.

According to the invention, the water treatment system comprises a first module comprising one or more aeration membrane(s). The term “aeration membrane” has its ordinary meaning in the art. By means of further guidance, and without limitation, an aeration membrane (also called a diffuser membrane) is a gas-permeable membrane which allows diffusion of a gas, such as (for instance) oxygen or air (or oxygen enriched air) into a liquid, such as (for instance) water. As used herein, the term “aeration” encompasses “oxygenation”. Accordingly, the term “aeration membrane” may equally encompass “oxygenation membrane”. Any type of aeration membrane can be used according to the present invention. The aeration membrane(s) may be microporous, dense, or composite (i.e. a mixture of microporous or dense). Combinations of different types of aeration membranes are also possible. By means of example, and without limitation aeration membranes can be made from elastomers, such as rubber, silicone, EPDM, or PDMS, or alternatively can for instance be ceramic. The skilled person will appreciate that certain materials may be appropriate for particular situations, and adapt accordingly. Also the shape or form of the aeration membrane can be chosen and/or adapted by the skilled person. By means of example, and without limitation, the aeration membrane can be a hollow fiber membrane, a curtain membrane, a tubular membrane, a tube spiral membrane, a flat sheet spiral, etc. In certain preferred embodiments, the aeration membrane is a hollow fiber membrane. Hollow fiber membranes are known in the art. By means of further guidance, and without limitation, in case of microporous membranes in certain embodiments a hollow fiber membrane may be a hollow (cylindrical) structure having a hollow core and porous walls. Alternatively, in case of dense membranes, in certain embodiments the membrane may be a plastic through which air/oxygen diffuses.

Aeration of the water to be treated according to the present invention is achieved at least through the aeration membrane, and may be passive or active (i.e. forced). Forced aeration typically involves the supply of air/oxygen under pressure. Accordingly, the aeration membrane in certain embodiments may be operably connected to a pressurised air/oxygen container or alternatively may be operatively connected to a compressor or blower (i.e. an aeration compressor or blower). Optionally, a mechanism for ensuring bubble aeration can additionally also be present.

One or more aeration membrane(s) may be provided in the water treatment system of the invention. The skilled person will appreciate that for instance the dimensions of the system, the amount of pollution, and/or flow rate of the water to be treated may necessitate more or fewer membranes (and the dimensions of the membranes may be adapted accordingly). In certain embodiments, the water treatment system comprises one aeration membrane. In certain embodiments, the water treatment system comprises two aeration membranes. In certain embodiments, the water treatment system comprises three aeration membranes. In certain embodiments, the water treatment system comprises four aeration membranes. In certain embodiments, the water treatment system comprises five or more aeration membranes. In certain embodiments, the one or more aeration membrane(s) allow for or are capable of an oxygen transfer capacity of at least 17.5 g C>2/m²/day within nominal operating conditions of the aeration membrane(s).

In certain embodiments, the first module in the water treatment system consists of, comprises, or is comprised in a bioreactor, such as a membrane-aerated biofilm reactor (MABR). Accordingly, in certain embodiments, the first module in the water treatment system consists of, comprises, or is comprised in a membrane-aerated biofilm reactor (MABR). MABR reactors are well known in the art. By means of further guidance, and without limitation, an MABR refers to a reactor comprising an aeration membrane, i.e. a gas-permeable membrane on the surface of which microorganisms can grow. Where the MABR is contacted with wastewater, the microorganisms can break down pollutants in the wastewater aerobically (in the presence of oxygen). MABR systems use specialized membranes such as those described above that allow the transfer of gases, such as oxygen, into the wastewater. These membranes provide a surface for biofilm formation, where microorganisms adhere and carry out biological treatment. Microorganisms, primarily bacteria, form a biofilm on the membrane surface. As the wastewater flows over the membrane, these microorganisms consume (organic) pollutants, breaking them down into simpler, less harmful compounds and/or convert into biomass. Oxygen or air is supplied to the microorganisms through the gas-permeable membranes. This aeration process is crucial for the growth and metabolic activities of the aerobic microorganisms. The oxygen transfer may occur naturally through the membrane, reducing the need for energy-intensive mechanical aeration systems. Alternatively active oxygenation may be performed (e.g. by compressors, blowers, or pressurized containers). Next to the aeration through the membrane, bubble aeration directly in the link may also be applied and in part contribute to the aeration and mixing of the water treatment system. MABR systems may also support both nitrification (conversion of ammonia to nitrate) and denitrification (conversion of nitrate to nitrogen gas) processes. This simultaneous nitrification and denitrification capability enhances the removal of nitrogenous compounds from wastewater.

According to the invention, the water treatment system comprises a second module comprising one or more filtration membrane(s).

The term “filtration membrane” has its ordinary meaning in the art. By means of further guidance, and without limitation, a filtration membrane is a semi-permeable membrane having selective permeability for particles or molecules. Accordingly, certain particles or molecules can pass through the membrane (i.e. the filtrate), whereas others cannot (i.e. the retentate). Typically, the pore size of the membrane determines what can pass through. Depending on the application, filtration membranes having a particular pore size (range) may be chosen. It will be understood however, that the filtration membrane will in any case allow water to pass through. Preferably, when contacted with wastewater comprising suspended (aggregated) solids, the filtration membrane will prevent at least part of the suspended (aggregated) solids (and (aggregated) biomass) to pass through. In certain embodiments, the filtration membrane is a microfiltration membrane or an ultrafiltration membrane. Also combinations of microfiltration and ultrafiltration membranes are envisaged. The terms microfiltration membrane and ultrafiltration membrane are known in the art. By means of further guidance, a microfiltration membrane is capable of removing (at least) larger particles and microorganisms, such as bacteria (i.e. is has a pore size adapted to prevent larger particles and bacteria to pass through). By means of further guidance, an ultrafiltration membrane is capable of removing (at least) smaller particles, colloids, proteins, and some viruses (i.e. it has a pore size adapted to prevent smaller particles, colloids, proteins, and some viruses to pass through). The skilled person will understand that pore size may be adapted according to the desired application (i.e. the pollutants to be removed and/or the desired purity of the treated water). In certain embodiments, the filtration membrane(s) has (have) a pore size ranging from 0.001 pm to 10 pm, preferably ranging from 0.01 to 1 pm. In certain preferred embodiments, the pore size ranges from 0.01 to 0.1 pm. The skilled person will appreciate that the pore size as referred to herein is the average pore size, such as the average pore diameter. It is also contemplated to combine filtration membranes having different pore sizes. The skilled person will appreciate that certain materials may be appropriate for particular situations, and adapt accordingly. Also the shape or form of the filtration membrane can be chosen and/or adapted by the skilled person. By means of example, and without limitation, the filtration membrane can be a flat plate inner permeate channel (I PC) membrane.

One or more filtration membrane(s) may be provided in the water treatment system of the invention. The skilled person will appreciate that for instance the dimensions of the system, the amount of pollution, and/or flow rate of the water to be treated may necessitate more or fewer membranes (and the dimensions of the membranes may be adapted accordingly). In certain embodiments, the water treatment system comprises one filtration membrane. In certain embodiments, the water treatment system comprises two filtration membranes. In certain embodiments, the water treatment system comprises three filtration membranes. In certain embodiments, the water treatment system comprises four filtration membranes. In certain embodiments, the water treatment system comprises five or more filtration membranes. In certain embodiments, the second module in the water treatment system consists of, comprises, or is comprised in a bioreactor, such as a membrane bioreactor (MBR). Accordingly, in certain embodiments, the first module in the water treatment system consists of, comprises, or is comprised in a membrane bioreactor (MBR). MBR reactors are well known in the art. By means of further guidance, and without limitation, an MBR refers to a reactor in which biological treatment is combined with filtration. MBRs use microorganisms to break down organic pollutants and remove nutrients (such as nitrogen and phosphorus) from wastewater. While typically, an MBR also requires aeration for providing oxygen to the microorganisms, (typically only provided as bubble aeration), according to the present invention preferably minimal bubble aeration is (additionally) provided, as aeration is already provided by the aeration membranes in the water treatment system of the invention. However, in certain embodiments bubble aeration is additionally provided.

According to the invention, the first module and the second module are in fluid connection, i.e. water can flow from the first module to the second module. In this connection, the first and second module can be provided in separate housings and a fluid connection can be established by one or more conduits between the separate housings. An embodiment of such arrangement is provided in Figure 1A. The provision of two or more conduits will advantageously allow the water to be circulated between the first and second module. Alternatively, the first and second module can be provided in the same housing. In such case the first and second module can respectively be considered to be the aeration membrane(s) and filtration membrane(s) per se (optionally including the affixtures to the housing). In these embodiments, water can flow freely between the respective membranes, thereby representing a fluid connection. An embodiment of such arrangement is provided in Figure 1 B. In both embodiments, the system will further comprise an influent conduit, for introducing the wastewater into the system and an effluent conduit for removing the treated water from the system (also referred to as the treated water effluent conduit). Accordingly, in particular embodiments, the first module and the second module are configured to allow water to recirculate between the first module and the second module. This can be referred to as “a closed loop”, irrespective of the fact that biomass is wasted from the loop.

According to the invention, the water treatment system comprises at least means for scouring the aeration membrane(s). Optionally, the water treatment system further comprises means for scouring the filtration membrane(s). Preferably, the water treatment system comprises means for scouring the aeration membrane(s) and means for scouring the filtration membrane(s). The means for scouring may be configured to effect scouring of or to operate the aeration membrane and/or filtration membrane scouring as described herein elsewhere.

Scouring of the aeration membrane and filtration membrane may be coupled or uncoupled, preferably uncoupled. Scouring of the aeration membrane and filtration membrane may be coupled. Scouring of the aeration membrane and filtration membrane may be uncoupled. Frequency of scouring of the aeration membrane and filtration membrane may be coupled or uncoupled. Frequency of scouring of the aeration membrane and filtration membrane may be coupled. Frequency of scouring of the aeration membrane and filtration membrane may be uncoupled. Duration of scouring of the aeration membrane and filtration membrane may be coupled or uncoupled. Duration of scouring of the aeration membrane and filtration membrane may be coupled. Duration of scouring of the aeration membrane and filtration membrane may be uncoupled. Frequency and duration of scouring of the aeration membrane and filtration membrane may be coupled or uncoupled. Frequency and duration of scouring of the aeration membrane and filtration membrane may be coupled. Frequency and duration of scouring of the aeration membrane and filtration membrane may be uncoupled. In a preferred embodiment, scouring of aeration and filtration membrane (frequency and/or duration) is uncoupled. Accordingly, aeration membrane and filtration membrane scouring (frequency and/or duration) may be regulated/controlled independently from one another.

As used herein, “coupled” refers to the same conditions applying to scouring of the aeration and filtration membrane. As used herein, “uncoupled” refers to the different conditions applying to scouring of the aeration and filtration membrane, i.e. aeration and filtration membrane scouring is differentially, individually, or separately regulated. Accordingly, uncoupled scouring of aeration and filtration membranes may include different scouring frequencies and/or different scouring duration (such as both different scouring frequencies and different scouring duration).

In certain embodiments, aeration membrane scouring is performed at most once per hour, such as at most once per 30 minutes. In certain embodiments, filtration membrane scouring is performed at least once per 5 minutes, such as at least once per minute. In certain embodiments, filtration membrane scouring is performed continuously. In certain embodiments, aeration membrane scouring is performed at most once per hour, such as at most once per 30 minutes, and filtration membrane scouring is performed at least once per 5 minutes, such as at least once per minute. In certain embodiments, filtration membrane scouring is performed continuously. In certain embodiments, aeration membrane scouring is performed at most once per hour, such as at most once per 30 minutes, and filtration membrane scouring is performed continuously.

Scouring intensity may be made dependent on oxidative status and/or suspended solids concentration.

Scouring of the filtration membrane may be discontinuous (e.g. time based, suspended solids concentration based, and/or oxidative status based, as described herein elsewhere) or continuous. In certain advantageous embodiments, scouring of the filtration membrane is continuous.

In certain embodiments, scouring frequency is based on the oxidative status. In certain embodiments, scouring duration is based on solids content, in particular total or volatile suspended solids content (concentration), such as determined by a total/volatile suspended solids sensor such as an optical (e.g. based on turbidity) or ultrasonic sensor, as known in the art. In certain embodiments, scouring frequency of the aeration membrane is based on the oxidative status. In certain embodiments, scouring duration of the aeration membrane is based on solids content, in particular total or volatile suspended solids content (concentration), such as determined by a total/volatile suspended solids sensor such as an optical (e.g. based on turbidity) or ultrasonic sensor, as known in the art. In certain embodiments, scouring frequency of the filtration membrane is based on the oxidative status. In certain embodiments, scouring duration of the filtration membrane is based on solids content, in particular total or volatile suspended solids content (concentration), such as determined by a total/volatile suspended solids sensor such as an optical (e.g. based on turbidity) or ultrasonic sensor, as known in the art. In certain embodiments, scouring frequency of the aeration membrane and filtration membrane is based on the oxidative status. In certain embodiments, scouring duration of the aeration membrane and filtration membrane is based on solids content, in particular total or volatile suspended solids content (concentration), such as determined by a total/volatile suspended solids sensor such as an optical (e.g. based on turbidity) or ultrasonic sensor, as known in the art.

In certain embodiments, scouring duration, in particular aerated membrane scouring duration, may be set based on a maximal suspended solids concentration. Accordingly, scouring duration, in particular aerated membrane scouring duration, may depend on a maximal suspended solids concentration threshold, i.e. scouring is effected until the maximal suspended solids concentration threshold is reached. Accordingly, not necessarily all biofilm is scoured off. The inventors have advantageously found that subsequent reattachment of the floc to the aeration membrane is improved when scouring is effected until lower suspended solids concentration is reached, compared to when higher suspended solids concentration is reached.

Scouring, in particular filtration membrane scouring, may be dependent on the (filtration) membrane pressure drop, in particular the evolution of pressure drop. Accordingly, scouring, in particular filtration membrane scouring may depend on a threshold pressure drop. In certain embodiments, scouring is effects if a predetermined threshold maximum pressure drop is reached.

As used herein, the term “scouring” has its ordinary meaning known in the art. By means of further guidance, and without limitation, scouring refers to the process (at least partially) cleaning membranes, such as to remove (at least partially) accumulated fouling and/or contaminants from the surface of the membrane, including biofilm, deposition of particles, organic matter, or scaling. As used herein, a scouring event or scouring operation refers to the time interval between activation of the means for scouring and inactivation of the means for scouring.

It will be understood that the means for scouring are provided such as to scour (at least) the side of the membrane which comes into contact with the (waste)water to be treated in the system, i.e. the (waste)water present in the system, in particular in the first and/or second module where the contaminated water resides. Accordingly, the means for scouring the aeration membrane(s) are configured to scour the gas permeate side, downstream side, or outer or shell side of the aeration membrane(s), and the means for scouring the filtration membrane(s) are configured to scour the feed side, liquid retentate side, or upstream side of the filtration membrane(s). Scouring may be effected by a variety of methods, such as including, but not limited to, air scouring, backwashing, chemical scouring, physical scouring, pulse scouring, shear scouring, biological scouring, etc. In certain preferred embodiments, the means for scouring comprise means for air scouring. Air scouring is well known in the art. By means of further guidance, and without limitation, air scouring involves the introduction of compressed air into the system to create bubbles that lift and agitate fouling particles (including biofilm) from the surface of the membrane. Compressed air may be introduced through diffusers or nozzles strategically placed at the bottom or along the sides of the membrane modules. The compressed air creates bubbles that rise through the membrane modules. As these bubbles ascend, they create a turbulent flow that lifts fouling particles from the membrane surface. The rising bubbles dislodge and agitate the accumulated solids (including biofilm), organic matter, and other contaminants that have adhered to the membrane surface. Air can also be introduced in said manner to mix the water and to contribute to oxygenating the water.

The term “biofilm” has its ordinary meaning in the art. By means of further guidance, and without limitation, biofilm is a (complex) community of microorganisms, primarily bacteria, that adhere to surfaces and are encased within a self-produced protective extracellular matrix of polymeric substances. A biofilm is a slimy layer of microorganisms that forms on various surfaces in damp or aqueous environments.

According to the invention, the water treatment system comprises means for determining the oxidative status of water. As used herein, the term oxidative status may be used interchangeably with oxidation-reduction status or redox status. By means of further guidance, and without limitation, the oxidative status refers to the balance between the reduction (gain of electrons) and oxidation (loss of electrons) reactions in a system relying on biological and/or chemical conversions, or environmental medium. It is a measure of the ability of one or more substances to donate or accept electrons, indicating its or their oxidative or reducing power. The oxidative status can be determined or approximated by a variety of analytical methods, including direct and indirect methods, such as without limitation the oxidation-reduction potential (ORP) measurement, dissolved oxygen (DO) measurement, oxygen uptake rate (OUR) measurement, hydrogen peroxide measurement, oxidative stress biomarker measurement, nitrate and/or nitrite measurement, etc. In general, any means for determining or approximating directly or indirectly the oxidative status of the (waste) water are suitable according to the present invention. In certain preferred embodiments, the means for determining the oxidative status comprise means for determining the oxidation-reduction potential or redox potential, such as an oxidation-reduction potential/redox potential sensor or probe, such as a redox electrode. Oxidation-reduction potential (ORP), also known as redox potential, is a measure of the ability of a chemical substance to undergo oxidation or reduction in a chemical reaction. It indicates the tendency of a substance to either lose electrons (oxidation) or gain electrons (reduction) when it reacts with other substances. Oxidationreduction potential is typically measured in volt (V), in particular millivolt (mV). ORP measures the electron activity in a solution. A higher ORP value indicates a more oxidizing environment, meaning the substance is more likely to donate electrons and undergo reduction. Conversely, a lower ORP value indicates a more reducing environment, indicating a higher tendency to gain electrons and undergo oxidation. At positive ORP values for instance, typically oxygen is present, which will energetically be the preferred electron acceptor or oxidant. Preferably, ORP values referred to herein are obtained when using an Ag/AgCI reference electrode with an electrolyte solution of 4M KOI. It will be understood by the skilled person that other reference electrodes with their associated electrolyte solutions can be used to establish ORP, such as saturated calomel electrodes, copper-copper(ll) sulfate electrodes, standard hydrogen electrodes or mercury-mercurous sulfate electrodes with their own ORP values corresponding to the before expressed range for the Ag/AgCI reference electrode with an electrolyte solution of 4M KOI.

It will be understood that the means for determining the oxidative status are provided such as to determine the oxidative status of (waste)water when present in the system, in particular in the first and/or second module where the contaminated water resides when the system is operative. Accordingly, the means for determining the oxidative status are provided and can be configured to determine the oxidative status of the water between the gas permeate side, downstream side, or outer side of the aeration membrane(s), and the feed side, liquid retentate side, or upstream side of the filtration membrane(s).

According to the invention, the means for scouring the aeration membrane(s) and optionally but preferably (if present) also the means for scouring the filtration membranes are configured to be operated based on the oxidative status of the (waste)water. Accordingly, in certain embodiments, the means for scouring the aeration membrane(s) and optionally but preferably (if present) also the means for scouring the filtration membranes are configured to be active or activated if a certain oxidative status threshold is reached. Conversely, in certain embodiments, the means for scouring the aeration membrane(s) and optionally but preferably (if present) also the means for scouring the filtration membranes are configured to be inactive or inactivated until a certain oxidative status threshold is reached or as long as a certain oxidative status threshold is not reached. The means for scouring will therefore be periodically activated. The means for scouring may be active during a particular oxidative status window, e.g. between a certain lower and upper oxidative status threshold. The oxidative status threshold for activating the means for scouring may, and preferably is, different from the oxidative status threshold for inactivating the means for scouring. This allows for the means for scouring to effectively achieve the desired level of scouring. Preferably, the means for scouring the aeration membrane are configured to be operated based on the oxidative status. Optionally, also the means for scouring the filtration membrane are configured to be operated based on the oxidative status. However, the means for scouring the filtration membrane in certain preferred embodiments are not configured to be operated based on oxidative status. Rather, in certain preferred embodiments, the means for scouring the filtration membrane are operated based on suspended solids content, such as TSS or VSS, as described herein elsewhere. In certain preferred embodiments, the means for scouring the filtration membrane are operated based on maximum suspended solids content, such as TSS or VSS, as described herein elsewhere, such as obtained during or after/at the end of scouring the aeration membrane. Filtration membrane scouring duration and/or frequency may be dependent on suspended solids content, such as maximum suspended solids content, such as TSS or VSS, as described herein elsewhere, such as obtained during or after/at the end of scouring the aeration membrane. It will be understood that in any case aeration membrane scouring and filtration membrane scouring need not occur simultaneously. Accordingly, filtration membrane scouring initiation may depend on a (immediately) prior aeration membrane scouring event and the associated/resulting suspended (maximum) solids content.

Aeration membrane scouring duration and/or frequency may be dependent on the evolution of suspended solids content, such as TSS or VSS, as described herein elsewhere, such as determined during a preset time after scouring the aeration membrane (e.g. the speed of suspended solids reduction during a predetermined time after ceasing aeration membrane scouring), as described herein elsewhere. Aeration membrane scouring duration and/or frequency may be dependent on the evolution of suspended solids content, such as TSS or VSS, as described herein elsewhere, such as determined after a preset time after scouring the aeration membrane (e.g. the level of suspended solids after a predetermined time ceasing aeration membrane scouring), as described herein elsewhere. Accordingly, aeration membrane scouring frequency may be (temporary) higher than required according to the oxidative status threshold. In certain embodiments, the means for scouring said one or more aeration membrane and optionally said one or more filtration membrane are configured to be activated if a predetermined particular suspended material concentration reduction is not reached during a predetermined time frame after a previous scouring event. Such reduction may for instance be 50% reduction, such as 60%, 70%, 80% or more, such as within 1 hour after scouring. In certain embodiments, the means for scouring said one or more aeration membrane and optionally said one or more filtration membrane are configured to be activated if a predetermined particular suspended material concentration is not reached during a predetermined time frame after a previous scouring event. Such concentration may for instance be 1 g TSS or VSS per liter, or less, such as within 1 hour after scouring. Such dynamic control of aeration membrane frequency scouring allows to improve for instance colloid degradation.

Filtration membrane scouring duration and/or frequency may be dependent on the evolution of suspended solids content, such as TSS or VSS, as described herein elsewhere, such as determined during a preset time after scouring the aeration membrane (e.g. the speed of suspended solids reduction during a predetermined time after ceasing aeration membrane scouring), as described herein elsewhere. Filtration membrane scouring duration and/or frequency may be dependent on the evolution of suspended solids content, such as TSS or VSS, as described herein elsewhere, such as determined after a preset time after scouring the aeration membrane (e.g. the level of suspended solids after a predetermined time ceasing aeration membrane scouring), as described herein elsewhere. Alternatively, the means for scouring the filtration membrane may be configured to be operated based on pressure drop. The skilled person will understand that operation may depend on predetermined thresholds of the respective parameter and that suitable thresholds may depend on for instance water treatment system dimensions, arrangement, etc and can be set as desired.

Alternatively, the means for scouring may be active for a particular preset or dynamic time. In certain embodiments, the means for scouring are activated for a time ranging from 1 minute to 10 minutes, preferably ranging from 2 minutes to 8 minutes, such as for 5 minutes. The skilled person will understand that the scouring time may depend on the dimensions of the system, the amount of pollution, and/or flow rate of the water to be treated.

In certain embodiments, the means for scouring are active or activated if the oxidationreduction potential (ORP) is at most +50 mV, preferably at most +10 mV, more preferably at most 0 mV, such as at most -10 mV or at most -50 mV or at most -200 mV. If nitrate is not (necessarily) to be removed, then a threshold of -50 mV may apply. If nitrate is (necessarily) to be removed, then a threshold of -200 mV may apply. In certain embodiments, the means for scouring are active or activated if the oxidation-reduction potential (ORP) is less than +50 mV, preferably less than +10 mV, more preferably less than 0 mV, such as less than -10 mV or less than -50 mV or less than -200 mV. If nitrate is not (necessarily) to be removed, then a threshold of -50 mV may apply. If nitrate is (necessarily) to be removed, then a threshold of - 200 mV may apply. Upon reaching these thresholds, the means for scouring may remain active or activated for a predetermined time (such as indicated above) and/or may remain active or activated until a predetermined oxidative threshold is reached, such as an ORP, DO or nitrate signal which is (at least) 5%, 10%, or 20% higher than the threshold for activating the means for scouring (e.g. until whichever time or oxidative status threshold is reached first or last).

In certain embodiments, the means for scouring are active or activated if dissolved oxygen (DO) is at most 2 mg/l, preferably at most 1 mg/l, more preferably at most 0.5 mg/l, such as at most 0.2 mg/l or at most 0.1 mg/l. In certain embodiments, the means for scouring are active or activated if dissolved oxygen (DO) is less than 2 mg/l, preferably less than 1 mg/l, more preferably less than 0.5 mg/l, such as less than 0.2 mg/l or less than 0.1 mg/l. Upon reaching these thresholds, the means for scouring may remain active or activated for a predetermined time (such as indicated above) and/or may remain active or activated until a predetermined oxidative threshold is reached, such as an ORP or DO which is (at least) 5%, 10%, or 20% higher than the threshold for activating the means for scouring (e.g. until whichever time or oxidative status threshold is reached first or last).

In certain embodiments, the water treatment system according to the invention is configured to aerate water (at least) through the one or more aeration membrane and filter water through the one or more filtration membrane; wherein the one or more aeration membrane and optionally the one or more filtration membrane are configured to be scoured upon reaching a predetermined oxidative status threshold of the water. As a result of the scouring, the microorganisms are released into the water present in the system resulting in the water containing particulate material, such as floc.

The oxidative status thresh be fixed or may be dynamic. Preferably, the oxidative status threshold is dynamic, i.e. the oxidative status threshold may be adapted according to certain criteria. In certain embodiments, the oxidative status threshold is set/adapted based on suspended solid concentration (e.g. TSS or VSS), such as TSS/VSS evolution/increase during scouring. Oxidative status influences detachment velocity of the biofilm during scouring. Using for instar VSS curve (i.e. the time-dependent TSS/VSS (increased) content during scouring), the oxidative status threshold can be adapted to improve the floc-filrn balance in the water treatment system, in particular in the first module, such as the IVIABR. When a slow TSS or VSS increase during scouring is observed, e.g. an optimum TSS or VSS is only reached after a long time, e.g. > of scouring, the oxidative status threshold may be increased, e.g. t laxirnurn of - sh situation, a slow increase is indicative of a more mature biofilm, which is more difficult to remove. Accordingly, the oxidative status threshold is increased (i.e. set such that scouring will be initiated sooner), such tha ext scouring event the biofilm is less difficult to remove. Whe TSS or VSS increase is observed, e.g. within 1 min, the threshold may be lowered, e.g. with a minimum of 0 or -50rnV, dependent on the matrix. Accordingly, in certain embodiments, the oxidative status threshold is a dynamic oxidative status threshold, wherein the oxidative status threshold is adapted/adjusted based on the time required to rear tain (increase in) suspended solids concentration (e.g. TSS or ring scouring. The skilled person will understand that adaptation of the oxidation status threshold may result from prior souring event(s); e.g. based on the time required tain (increase) in suspended solids (e.g. TSS or VSS) during a previous scouring event (or integrative during multiple previous scouring events), such that each scouring event (or integrative multiple previous scouring events) may lead to adaptation of a subsequent oxidative status threshold for i nitiati i scouring event. Advantageously, dynamic adaptation of oxidati ve status thresholds may for instance allow for taking into account growth rate of the microbial biomass (which may be faster or slower depending on the influent pollutant concentration, but likewise also for instance ternperal ects which affect growth rate). If for Instance growth rate Is faste iher oxidative status threshold may be set to prevent full maturation of the biofilm (i.e. by earlier scouring). Setti gher oxidative status threshold typically entails an increase in scouring frequency. Accordingly, aeration membrane scouring frequency may be dependent on the evolution of suspended solids content after scouring initiation, (e.g. the speed of suspended solids increase during a predetermined time after initiating aeration membrane scouring). Accordingly, aeration membrane scouring frequency may be (temporary) higher than required according to the oxidative status threshold. In certain embodiments, the means for scouring said one or more aeration membrane and optionally said one or more filtration membrane are configured to be activated if a predetermined particular suspended material concentration increase is not reached during a predetermined time frame after a previous scouring event. Such increase may for instance be 50% increase, such as 60%, 70%, 80%, 90%, 95% or more, such as within 20 seconds after initiating scouring. In certain embodiments, the means for scouring said one or more aeration membrane and optionally said one or more filtration membrane are configured to be activated if a predetermined particular suspended material concentration is not reached during a predetermined time frame after a previous scouring event. Such concentration may for instance be 1 g TSS or VSS per liter, or less, such as within 20 seconds after initiating scouring. Such dynamic control of aeration membrane frequency scouring allows to prevent biofilm full maturation. In certain embodiments, the predetermined oxidative status threshold is dynamically adapted based on the average time to reach a predetermined suspended particulate material concentration or concentration increase after initiation of one or more previous scouring events. The concentration may for instance be 1 g TSS or VSS per liter after 20 seconds. The concentration increase may for instance be at least 50%, such as at least 75%, at least 85% or at least 95% after 20 seconds.

In certain embodiments, the water treatment system according to the invention is configured to remove at least part of the particulate material, such as floc from the water during and/or after scouring of the one or more aeration membrane and optionally of the one or more filtration membrane.

In certain embodiments, the water treatment system according to the invention is configured to remove at least part of the particulate material, such as floc present in the water if the particulate material, such as floc content of the water exceeds a predetermined level, such as floc threshold, until a threshold oxidative status in said water is reached, and/or until a threshold particulate material, such as floc content or content reduction in said water is reached, as described herein elsewhere.

In certain embodiments, the water treatment system comprises means for determining the pH of the (waste)water. Similarly to the means for determining the oxidative status, it will be understood that the means for determining the pH are provided such as to determine the pH of the (waste)water when present in the system, in particular in the first and/or second module where the contaminated water resides. Accordingly, the means for determining the pH are provided and can be configured to determine the pH of the water between the permeate side, downstream side, or outer side of the aeration membrane(s), and the feed side, liquid retentate side, or upstream side of the filtration membrane(s).

In certain embodiments, the water treatment system comprises means for determining the solids content, in particular the suspended solids content and/or biomass and/or particulate material such as floc content in the (waste)water. Similarly to the means for determining the oxidative status, it will be understood that the means for determining the solids/biomass content are provided such as to determine the solids/biomass content of the (waste)water when present in the system, in particular in the first and/or second module where the contaminated water resides. Accordingly, the means for determining the solids/biomass content are provided and can be configured to determine the solids/biomass content of the water between the gas permeate side, downstream side, or outer side of the aeration membrane(s), and the feed side, liquid retentate side, or upstream side of the filtration membrane(s). Any sensor or probe that directly or indirectly measures the solids/biomass content may be used. By means of example, and without limitation a total suspended solids sensor, a turbidity sensor, or an optical sensor may be used.

During and after scouring, the biofilm which was present on the aeration and/or filtration membranes is detached and at least partially disintegrated to form a sludge in which larger particles, i.e. “floc”, are suspended. As used herein, "floc" refers to a collection of suspended/partially disintegrated/detached biofilm (that may have clumped together in the water or wastewater system), i.e. floccular or (detached) biofilm fragments. At least part of this floc, may be periodically removed (extracted) from the system during a “wasting” operation. It will be understood that also other larger particular material may be removed during a wasting step. The wasting step may commence after scouring or may already commence during scouring. Wasting may occur every time after (aeration) membrane scouring, but need not necessarily occur every time after (aeration) membrane scouring. Wasting in addition or instead may depend on other parameters, such as suspended solids content (including maximum suspended solids content during or after/at the end of scouring), as described herein elsewhere. Accordingly, in certain preferred embodiments, scouring and wasting are uncoupled (i.e. individually controlled). Periodic removal of floc/particulate material may depend on the particulate material concentration, i.e. suspended solids (e.g. TSS or VSS), such as based on the highest suspended solids concentration (e.g. as reached during or after/at the end of scouring). Accordingly, wasting may be regulated based on a suspended solids (e.g. TSS or VSS threshold). In certain embodiments, particulate material may be removed if the concentration exceeds 0.5 g/l, preferably if the concentration exceeds 0.1 g/l. Making wasting dependent on suspended solids concentration advantageously allows minimizing wasting volume while maximizing suspended solids removal, i.e. maximizing suspended solid concentration for removal. Accordingly, in certain embodiments, wasting is effected when a certain minimal suspended solids concentration (such as TSS or VSS) is reached, such as during or after/at the end of scouring (preferably scouring the aeration membrane), i.e. when a threshold suspended solids concentration is reached, such as during or after/at the end of scouring (preferably scouring the aeration membrane). The maximum suspended solids concentration is typically reached during scouring. Accordingly, in certain embodiments, wasting is effected upon reaching a maximum suspended solids concentration threshold (i.e. a threshold to be considered a the time when the maximum suspended solids concentration is reached). The skilled person will understand that during prolonged scouring, the maximum suspended solids concentration may be reached prior to the end of scouring (e.g. when scouring continues while all biofilm is detached from the membrane). As such, the maximum suspended solids concentration may not necessarily be reached at the end of scouring, but may be reached already during scouring.

In addition, or in the alternative, a minimum waste interval may be set, i.e. a minimal time between wasting events. This may likewise be determined based on the suspended solids, such as TSS or VSS, in particular during or after/at the end of scouring. Accordingly a minimum suspended solids concentration threshold may be set, below which no wasting is effected and only above which wasting is effected. This may prevent washout of biomass (i.e. loss of biomass altogether, or to the extent that biofilm formation (reattachment) is impeded or otherwise hampered, such as for instance too little biomass is present to efficiently digest organic and inorganic particulate material in a reasonable time frame.

In addition, or in the alternative, wasting frequency/intervals may be set based on the amount of organic or inorganic particulate material (such as colloids) present in the water to be treated. It will be understood that particulate organic material excludes biomass in this context. Organic or inorganic particulate material (such as colloids) are part of the suspended solids, and in particular part of the chemical oxygen demand (COC) fraction, i.e. digestible by the microbes. Organic or inorganic particulate material (such as colloids) typically do not settle and cannot be efficiently removed during wasting. The evolution of suspended solids after scouring can be used as a proxy for organic or inorganic particulate material (such as colloids) concentration. In particular, after scouring, biomass (i.e. bacteria) will reattach to the (aeration) membrane, while organic or inorganic particulate material (such as colloids) will not. Accordingly, a comparatively faster drop or higher reduction in suspended solids indicates a lower organic or inorganic particulate material (such as colloids) concentration than a slower drop or lower reduction in suspended solids. Hence, suspended solids (evolution) determination may be a measure for organic or inorganic particulate material (such as colloids) degradation efficiency. As advantageously organic or inorganic particulate material (such as colloids) reduction is desired (as it may clog for instance filtration membranes), such may be achieved by reducing wasting frequency (and hence increasing sludge retention time, also called solids retention time (SRT)). Accordingly, wasting may be prevented as long as a certain threshold suspended solids concentration is not reached, such as at a predetermined time point after scouring (e.g. when all or most (e.g. at least 90%) of the floc has been reattached to the aeration membrane), such as for instance e.g. 1 g TSS or VSS per liter after 60 min.

Alternatively (or in addition), scouring duration may be increased, so as to allow to increase accessibility of the organic or inorganic particulate material (such as colloids) or more general COD to the biomass (which is in suspension as a result from scouring, and will not reattach during scouring). Accordingly, scouring may be continued in as long as a certain threshold suspended solids concentration is not reached. Alternatively, scouring may be continued in a subsequent scouring event as long as a certain threshold suspended solids concentration was not reached, such as at a predetermined time point after a previous scouring event (e.g. when all or most (e.g. at least 90%) of the floc has been reattached to the aeration membrane), such as for instance e.g. 1 g TSS or VSS per liter after 60 min.

Alternatively (or in addition), scouring frequency may be increased, so as to allow to increase accessibility of the organic or inorganic particulate material (such as colloids) or more general COD to the biomass (which is in suspension as a result from scouring, and will not reattach during scouring). Accordingly, scouring frequency may be increased as long as a certain threshold suspended solids concentration is not reached (e.g. at steady state levels in between scouring events, such as after reattachment of the biomass). Alternatively, the increased scouring frequency may be maintained in a subsequent scouring event as long as a certain threshold suspended solids concentration was not reached, such as at a predetermined time point after a previous scouring event (e.g. when all or most (e.g. at least 90%) of the floc has been reattached to the aeration membrane), such as for instance e.g. 1 g TSS or VSS per liter after 60 min. Alternatively, scouring frequency may be increased until a threshold solids concentration is reached at a predetermined time point after scouring (e.g. when all or most (e.g. at least 90%) of the floc has been reattached to the aeration membrane), such as for instance e.g. 1 g TSS or VSS per liter after 60 min.

In certain embodiments, the predetermined or threshold suspended solids concentration is based on the average maximum suspended solids concentration during or after one or more previous scouring events (in particular aeration membrane scouring events). The one or more previous scouring events may for instance be 5, 10, 20, or more previous scouring events, or may be all scouring events during the previous 5, 10, 24, or 48 hours. Such dynamic adaptation of threshold advantageously allows tailoring the system to adopt to fluctuations in water composition (e.g. influent water having more pollutants at one point in time whereas having less pollutants at a different point in time). It will be understood that at startup, no previous scouring events have occurred. In such case, a threshold may for instance be set based on previous experience, concentration of pollutants, etc.

Scouring duration may likewise be increased in order to achieve the wasting threshold. Indeed, if wasting is set on a suspended solids concentration threshold, an increase in the duration of scouring may increase the suspended solids concentration, thereby reaching the suspended solids threshold concentration faster. This may be relevant if the system is operated on a predetermined SRT, as described herein elsewhere.

Accordingly, in certain embodiments, the water treatment system of the invention further comprises means for extracting or wasting (larger) particulate material, such as floc. The means for extracting or wasting (larger) particulate material, such as floc may be configured to effect extraction/wasting or to be operated the as described herein elsewhere. As used herein, the terms means for wasting and extracting particular material are used interchangeably.

The particulate material may be periodically removed, such as after settling or during or after scouring. Settling may be effected by means known in the art, such as without limitation by settling legs. Typically, extraction valves may operably be connected with such settling legs to effect settled sludge extraction. The means for extracting particulate material may be operably connected to the first module and/or the second module, preferably at least the first module. In particular in cases where the first and second modules are provided in separate housings, the means for extracting particulate material may be operably connected to the first module. The skilled person will understand that together with the particulate material also at least some (waste)water is co-extracted, which may be subjected to further downstream treatment or separation from the particulate material and optional reintroduction in the water treatment system. In certain embodiments, the water treatment system of the invention further comprises means for extracting or wasting (larger) particulate material, such as floc configured to remove or extract (larger) particulate material, such as floc for a particular time. In certain embodiments, the means are configured to remove or extract (larger) particulate material, such as floc during scouring. In certain embodiments, means are configured for extracting or wasting (larger) particulate material, such as floc configured to remove or extract (larger) particulate material, such as floc after scouring. In certain embodiments, the means can be configured for extracting or wasting (larger) particulate material, such as floc configured to remove or extract (larger) particulate material, such as floc during and/or after scouring. In each of these embodiments, the means can be configured to remove or extract (larger) particulate material, for a particular time or until a particulate material threshold concentration is reached. For instance, the means can be configured to remove or extract (larger) particulate material as long as the particulate material concentration is at least 0.1 g/l; such as 0.5 g/l or 2 g/l. Alternatively, the means can be configured to remove or extract particulate material until a particulate material reduction is reached (such as during and/or after scouring), such as for instance a reduction of at least 5 wt% of particulate material, preferably a reduction of at least 10 wt%, more preferably a reduction of at least 20 wt%, such as a reduction of at least 30 wt%. In particular embodiments, the means for extracting or wasting (larger) particulate material, such as floc is a dedicated conduit.

In certain embodiments, the water treatment system of the invention further comprises means for extracting or wasting (larger) particulate material, such as floc configured to remove or extract (larger) particulate material, such as floc for a particular time during scouring. In certain embodiments, the water treatment system of the invention further comprises means for extracting or wasting (larger) particulate material, such as floc configured to remove or extract (larger) particulate material, such as floc for a particular time after scouring. In certain embodiments, the water treatment system of the invention further comprises means for extracting or wasting (larger) particulate material, such as floc configured to remove or extract (larger) particulate material, such as floc for a particular time during and after scouring.

In certain embodiments, the water treatment system of the invention further comprises means for extracting or wasting (larger) particulate material, such as floc configured to remove or extract (larger) particulate material, such as floc until a particulate material threshold concentration is reached (such as during and/or after scouring). In certain embodiments, the water treatment system of the invention further comprises means for extracting or wasting (larger) particulate material, such as floc configured to remove or extract (larger) particulate material, such as floc as long as a particulate material threshold concentration is exceeded (such as during and/or after scouring). In certain embodiments, the water treatment system of the invention further comprises means for extracting or wasting (larger) particulate material, such as floc configured to remove or extract (larger) particulate material, such as floc as long as the particulate material concentration is at least 0.1 g/l; such as 0.5 g/l or 2 g/l (such as during and/or after scouring).

In certain embodiments, the water treatment system of the invention further comprises means for extracting or wasting (larger) particulate material until a particulate material reduction is reached (such as during and/or after scouring), such as for instance a reduction of at least 5 wt% of particulate material, preferably a reduction of at least 10 wt%, more preferably a reduction of at least 20 wt%, such as a reduction of at least 30 wt%.

As used herein, Solids Retention Time (SRT), also known sometimes as Sludge Retention Time, has its ordinary meaning in the art. By means of further explanation, SRT refers to the average amount of time that the biomass (microorganisms) remains in the system before being removed. It is a measure of biomass turnover. It may be expressed as the ratio of total biomass and biomass wasted per time unit (preferably per day).

In certain embodiments, the water treatment system of the invention is operated such as to achieve a predetermined SRT. Accordingly, wasting and optionally also scouring frequency and/or duration are set or effected so as to achieve the predetermined SRT. A minimum frequency of scouring is required to prevent formation of a mature biofilm, at least once per SRT, for example SRT of two days. The scouring frequency can increase to once per hour or more often based on a set SRT target. Likewise, the wasting frequency can be set to achieve the predetermined SRT. The skilled person will understand that it is not advisable to effect wasting only once during a SRT (e.g. by scouring all biofilm and subsequently wasting all scoured biofilm). Typically, the SRT will be achieved over several scouring and wasting events, whereby a fraction of floc is removed in each wasting event or wherein only a fraction of biofilm is scoured off during each scouring event, which fraction may be partially or completely wasted.

In certain embodiments, SRT may be dynamic, and may for instance be dependent on or set based on maximal suspended solids, such as during or after/at the end of scouring. For instance, a high suspended solids content during or after/at the end of scouring may invoke a decrease in SRT. Accordingly, a high suspended solids content during or after/at the end of scouring may invoke an increase in wasting frequency (and optionally scouring frequency). The skilled person will understand that in such situation, an increase in wasting frequency entails an increase in the amount of suspended solids (such as floc) wasting.

The present inventors have found that precise SRT control/management allows more precise steering based on incoming fluctuations. In general, dynamic adaptation of threshold (such as oxidative status threshold, (maximum or minimum) suspended solids content or evolution threshold, etc.) advantageously allows tailoring the system to adopt to fluctuations in water composition (e.g. influent water having more pollutants at one point whereas having less pollutants at a different point), to which operation of the various components of the system can be tailored (e.g. scouring frequency and/or duration, wasting, recirculation, aeration, filtration, SRT, oxidative status, etc.).

In certain embodiments, the water treatment system of the invention comprises one or more pumps. In certain embodiments, the water treatment system of the invention comprises one or more pumps to effect scouring. In particular embodiments, the one or more pumps to effect scouring are connected to the means for scouring the aeration membrane. In certain embodiments, the water treatment system of the invention comprises one or more pumps to effect circulation of the water in the system. In particular embodiments the one or more pumps to effect circulation of the system are connected to an effluent conduit. In certain embodiments, the water treatment system of the invention comprises one or more pumps to effect particulate material wasting, also referred to as a solid waste extraction pump or wasting pump. In particular embodiments the one or more pumps to effect the particulate material wasting are connected to the dedicated wasting conduit. In certain embodiments, the water treatment system of the invention comprises one or more pumps to effect filtration. In certain embodiments, filtration is effected by means of gravity. In certain embodiments, the water treatment system of the invention comprises one or more pumps to effect introduction of water to be treated in the system. In certain embodiments, introduction of water to be treated is effected by means of gravity. In certain embodiments, the water treatment system of the invention comprises one or more pumps to effect aeration.

In certain embodiments, the water treatment system of the invention comprises one or more valves. In certain embodiments, the water treatment system of the invention comprises one or more valves configured to regulate the flow of water in a conduit.

In certain embodiments, the water treatment system of the invention comprises one or more compressors or blowers. In certain embodiments, the water treatment system of the invention comprises one or more compressors or blowers configured to effect aeration through the membranes. In certain embodiments, the water treatment system of the invention comprises one or more compressors or blowers configured to effect scouring, mixing and/or add-on aeration in the bulk liquid. In certain embodiments, the water treatment system of the invention comprises one or more compressor or blower configured to effect aeration.

In certain embodiments the water treatment system of the invention comprises a controller. In particular embodiments the controller regulates the means for scouring the aeration membrane(s) and/or means for scouring the filtration membrane(s). In particular embodiments, where present, the controller may also regulate one or more of the one or more (re)circulation pumps, the scouring compressor/blower, the solid waste extraction pump, the effluent (i.e. treated water) pump and/or the influent (i.e. water to be treated) pump. In particular embodiments the controller receives input from the means for determining the oxidative status. In further embodiments, where present, the controller may further receive input from a means for determining the solids content, a means for determining the pH, a means for extracting solids and/or biomass. In further embodiments, the controller may further regulate one or more valves in the system such as, where present a valve on the influent conduit, a valve on the effluent conduit, a valve on the wasting conduit, etc. In particular embodiments, the controller may further regulate the scouring compressor/blower.

The water treatment system of the invention as described herein may be configured in such way that aeration and/or filtration is not active during scouring and/or wasting. This can for instance be effected by preventing influent from entering the system and/or preventing effluent from leaving the system, such as by closing valves suitably provided or positioned stopping the appropriate pumps (e.g. influent and/or effluent pumps). The water treatment system of the invention as described herein may be configured in such way that aeration and filtration is not active during scouring and wasting. The water treatment system of the invention as described herein may be configured in such way that aeration and filtration is not active during scouring. The water treatment system of the invention as described herein may be configured in such way that aeration and filtration is not active during wasting. The water treatment system of the invention as described herein may be configured in such way that aeration is not active during scouring and/or wasting. The water treatment system of the invention as described herein may be configured in such way that aeration is not active during scouring. The water treatment system of the invention as described herein may be configured in such way that aeration is not active during wasting. The water treatment system of the invention as described herein may be configured in such way that aeration is not active during scouring and wasting. The water treatment system of the invention as described herein may be configured in such way that filtration is not active during scouring and/or wasting. The water treatment system of the invention as described herein may be configured in such way that filtration is not active during scouring. The water treatment system of the invention as described herein may be configured in such way that filtration is not active during wasting. The water treatment system of the invention as described herein may be configured in such way that filtration is not active during scouring and wasting.

The water treatment system of the invention as described herein may be configured in such way that aeration and/or filtration is not active for a predetermined time after scouring and/or wasting. The water treatment system of the invention as described herein may be configured in such way that aeration and filtration is not active for a predetermined time after scouring and wasting. The water treatment system of the invention as described herein may be configured in such way that aeration and filtration is not active for a predetermined time after scouring. The water treatment system of the invention as described herein may be configured in such way that aeration and filtration is not active for a predetermined time after wasting. The water treatment system of the invention as described herein may be configured in such way that aeration is not active for a predetermined time after scouring and/or wasting. The water treatment system of the invention as described herein may be configured in such way that aeration is not active for a predetermined time after scouring. The water treatment system of the invention as described herein may be configured in such way that aeration is not active for a predetermined time after wasting. The water treatment system of the invention as described herein may be configured in such way that aeration is not active for a predetermined time after scouring and wasting. The water treatment system of the invention as described herein may be configured in such way that filtration is not active for a predetermined time after scouring and/or wasting. The water treatment system of the invention as described herein may be configured in such way that filtration is not active for a predetermined time after scouring. The water treatment system of the invention as described herein may be configured in such way that filtration is not active for a predetermined time after wasting. The water treatment system of the invention as described herein may be configured in such way that filtration is not active for a predetermined time after scouring and wasting. In certain embodiments, such predetermined time ranges from 5 minutes to 1 hour, preferably from 10 minutes to 30 minutes, such as 20 minutes. The skilled person will understand that the time may depend on the dimensions of the system, the amount of pollution, and/or the amount of particulate material.

The water treatment system of the invention as described herein may be configured in such way that aeration and/or filtration is not active until a predetermined reduction in suspended particulate material is reached after scouring and/or wasting. After scouring, particulate material, in particular floc will reattach to the membranes, resulting in a decrease in suspended particulate material.

The water treatment system of the invention as described herein may be configured in different ways (all of which are not necessarily mutually exclusive). It may be configured in such way that aeration and filtration and optionally recirculation is not active until a predetermined reduction in suspended particulate material (e.g. (maximum) TSS or VSS) is reached after scouring and wasting; that aeration and filtration and optionally recirculation is not active until a predetermined reduction in suspended particulate material (e.g. (maximum) TSS or VSS) is reached after scouring; that aeration and filtration and optionally recirculation is not active until a predetermined reduction in suspended particulate material (e.g. (maximum) TSS or VSS) is reached after wasting: that aeration and optionally recirculation is not active until a predetermined reduction in suspended particulate material (e.g. (maximum) TSS or VSS) is reached after scouring and/or wasting; that aeration and optionally recirculation is not active until a predetermined reduction in suspended particulate material (e.g. (maximum) TSS or VSS) is reached after scouring; that aeration and optionally recirculation is not active until a predetermined reduction in suspended particulate material (e.g. (maximum) TSS or VSS) is reached after wasting; that aeration and optionally recirculation is not active until a predetermined reduction in suspended particulate material (e.g. (maximum) TSS or VSS) is reached after scouring and wasting; that filtration and optionally recirculation is not active until a predetermined reduction in suspended particulate material (e.g. (maximum) TSS or VSS) is reached after scouring and/or wasting; that filtration and optionally recirculation is not active until a predetermined reduction in suspended particulate material (e.g. (maximum) TSS or VSS) is reached after scouring; that filtration and optionally recirculation is not active until a predetermined reduction in suspended particulate material (e.g. (maximum) TSS or VSS) is reached after wasting; that filtration and optionally recirculation is not active until a predetermined reduction in suspended particulate material (e.g. (maximum) TSS or VSS) is reached after scouring and wasting. In certain embodiments, such predetermined reduction ranges from 10% to at least 80%, such as 90% or 100%, preferably from 50% to at least 80%, such as 90% or 100%, such as at least 70%. The skilled person will understand that the time it will take may depend on the dimensions of the system, the amount of pollution, and/or the amount of particulate material. In certain embodiments, the predetermined reduction in suspended particulate material is at least 5 wt% of particulate material, preferably a reduction of at least 10 wt%, more preferably a reduction of at least 20 wt%, such as a reduction of at least 30 wt%.

In certain embodiments, such predetermined time ranges from 5 minutes to 1 hour, preferably from 10 minutes to 30 minutes, such as 20 minutes. The skilled person will understand that the time may depend on the dimensions of the system, the amount of pollution, and/or the amount of particulate material. In certain embodiments, the predetermined reduction in suspended particulate material is at least 5 wt% of particulate material, preferably a reduction of at least 10 wt%, more preferably a reduction of at least 20 wt%, such as a reduction of at least 30 wt%.

In certain embodiments, particular components of the water treatment system of the invention may be configured to operate under certain conditions depending on more than one parameter. For instance, the means for scouring, wasting, recirculation, aeration, filtration, etc. may be active/activated or inactive/deactivated based on one or more parameters, such as based on one or more parameter thresholds, such as oxidative status, (maximum or minimum) suspended solids content, evolution of suspended solids content, etc. In certain embodiments, the status may depend on the respective (threshold) conditions being fulfilled for one, more, or all of the parameters. In certain embodiments, the status may depend on the first respective (threshold) condition being fulfilled for one of the parameters. By means of example, and without limitation, scouring duration may last until a preset suspended solids concentration is reached and/or for a preset amount of time, whereby ultimately scouring duration lasts until the first condition is reached (i.e. preset suspended solids concentration of preset time). Similar considerations may apply for other parametrized operational conditions as described herein elsewhere, including wasting, recirculation, etc..

In an aspect, the invention relates to a water treatment, purification, or filtration method with the water treatment, purification, or filtration system according to the invention as described herein. In a related aspect, the invention relates to the use of a water treatment, purification, or filtration system according to the invention as described herein for water treatment, purification, or filtration.

In a related aspect, the invention relates to a method of water treatment, purification, and/or filtration, comprising in a water treatment system aerating the water through one or more aeration membranes, filtering the water through one or more filtration membranes and scouring the one or more aeration membranes and (optionally) the one or more filtration membranes based on the oxidative status of said water.

In particular embodiments, said water is wastewater, such as wastewater that did or did not undergo one or more prior treatment steps. In particular embodiments, the pre-treatment of the water comprises physical, chemical and/or biological processes. In particular embodiments, the water has undergone a treatment involving anaerobic digestion (i.e. the water is a digestate). In particular embodiments, the water is grey water, black water and/or yellow water, and/or wastewater from household, office, and/or industrial or agricultural activities.

In particular embodiments the method comprises scouring the one or more aeration membranes and optionally the one or more filtration membranes when a predetermined oxidative status threshold of the water is reached. In particular embodiments, the method comprises introducing wastewater into a water treatment system according to the present invention. In certain embodiments, the invention relates to a method of water treatment, purification, and/or filtration, comprising in a water treatment system according to the invention as described herein aerating the water through the one or more aeration membranes and filtering the water through the one or more filtration membranes, wherein when a predetermined oxidative status threshold of the water is reached the one or more aeration membranes and optionally the one or more filtration membranes are scoured. In certain embodiments, in particular in cases where the first and second modules are provided in separate housings, during scouring of the membranes recirculation of the water in the system is prevented or interrupted and/or filtration is prevented or interrupted. Recirculation may be suitably regulated by one or more valve, such as positioned to prevent flow through one or more conduits connecting the first module and the second module. Such valve(s) may be regulated by the controller. Alternatively (or in addition) recirculation may be regulated by regulation of a controller-based recirculation pump. This has the added advantage that the scoured biomass does not block or clog the filtration membrane(s) by sludge attachment to the filtration membrane(s). In certain embodiments, recirculation may be controlled based on the suspended solids content (such as TSS or VSS). In certain embodiments, recirculation may be active as long as a predetermined maximum suspended solids content is not reached. In certain embodiments, recirculation may be inactive as long as a predetermined suspended solids minimum content is not reached. This may for instance be the case during or after/at the end of scouring, when suspended solids content is increased. In this way, fouling or clogging of the filtration membrane may be reduced. In addition, in certain embodiments, filtration may likewise be inactive (such as during scouring, as described herein elsewhere). Accordingly, in certain embodiments, filtration may be controlled based on the suspended solids content (such as TSS or VSS). In certain embodiments, filtration may be active as long as a predetermined maximum suspended solids content is not reached. In certain embodiments, filtration may be inactive as long as a predetermined suspended solids minimum content is not reached. This may for instance be the case during or after/at the end of scouring, when suspended solids content is increased. In this way, fouling or clogging of the filtration membrane may be reduced. In certain embodiments, the water treatment system of the invention comprises means for recirculation.

In certain embodiments, the water treatment system of the invention comprises means for recirculation configured to effect recirculation or configured to operate as described herein elsewhere.

In certain embodiments, scouring of the aeration membrane and/or filtration membrane may be effected or operated as described herein elsewhere.

In certain embodiments, wasting may be effected or operated as described herein elsewhere.

In a related aspect, the invention relates to a water filtration system configures or specifically adapter to perform the method of water treatment, purification, and/or filtration according to the invention as described herein.

It will be understood that all embodiments, components, parameters, values, etc which are described in the context of the water treatment, purification, or filtration system above equally, explicitly, and integrally apply to the water treatment, purification, or filtration method.

The aspects and embodiments of the invention are further supported by the following nonlimiting examples. The following examples, including the experiments conducted and the results achieved, are provided for illustrative purposes only and are not constructed as limiting the present invention. The use of these and other examples anywhere in the specification is illustrative only and in no way limits the scope and meaning of the invention or of any exemplified term. Likewise, the invention is not limited to any particular preferred embodiments described here. Indeed, many modifications and variations of the invention may be apparent to those skilled in the art upon reading this specification, and such variations can be made without departing from the invention in spirit or in scope. The invention is therefore to be limited only by the terms of the appended claims along with the full scope of equivalents to which those claims are entitled.

EXAMPLES

EXAMPLE 1 : Set up of a water treatment system according to an embodiment of the invention

A water treatment system was designed and constructed as illustrated in Figure 4A comprising an MABR with hollow fiber membranes for aeration (H) (V= 3.5L) and an MBR (V=1.5 L) comprising a flat plate inner permeate channel (I PC) membrane for filtration (C), connected through recirculation tubing with a flow could be imposed by a pump (F) during different phases of the steady state operation which was controlled by a programmable microcontroller (non visible, in housing of pump N), connected to the computer (T). During scouring of the MABR, the flow to the MBR was stopped, as to prevent the biomass clogging the filtration membrane. At the same time, biomass was wasted with the help of a microcontroller an controlled pump (B) and collected in a vessel (G) Effluent (A) was extracted using the microcontroller-controlled pump (N) continuously but was regulated using the level controller (I) as to not drain the reactor if permeate flux would exceed influent (U) flow (imposed by pump R). An overflow vessel (M) was connected in case of failures or lowered permeate flux.

The MABR and MBR are provided with means for scouring the aeration/filtration membranes in the form of bubble aeration. For the MABR, scouring was done controlled by the ORP sensor (H) signal relayed to the microcontroller, to pump S, injecting air at a flowrate of 5 liter per min for a period of 5 min once the threshold for scouring was reached. The MBR scouring was regulated by a timer (Q), but in later operational stages was also controlled by microcontroller, using the same timing as the MABR scouring.

The influent was refrigerated at 4°C (U) to ensure stability. A heating device was connected (D) to the reactor to simulate the real temperature (35 °C) of the treated wastewater. Additionally, a pH & DO (dissolved oxygen) probe (H) were connected (L) for monitoring. Figure 4B provides an alternative set-up a water treatment system according to an embodiment of the invention.

EXAMPLE 2: Operation of a water treatment system according to an embodiment of the invention

The reactor as described in Example 1 was inoculated using sludge from a decentralized treatment facility for grey water & black water digestate. The water treated here was a synthetic grey water matrix, consisting of a mixture of shampoos, soaps and conditioners, supplemented with nitrogen and phosphorus to yield a COD:N:P ratio of 50:1 :0.2 and a concentration of COD around 600 mg O2/L. To ensure enough contact between the biomass from influent and membrane, the reactor was operated for 2 days without wasting (e.g. loss of biomass), after which normal operation could be implemented.

Normal operation consists of a three-phase control system (Figure 3), where in phase 1 , scouring is performed for a set time or until a certain VSS setpoint is reached. During this phase, wasting can be performed to reach a desired amount of biofilm to be removed from the system.

After this phase a second, re-attachment phase starts. In this specific setup, it was found that regardless of operational variability (such as loading rate, ORP, DO, etc.), after 20 minutes of non-scouring operation, 75% of the biomass would be re-attached to the MABR membranes (Figure 7). By only starting recirculation to the MBR after this given time, biomass exposure to the MBR can be minimized, which greatly reduces clogging of the membrane.

The third and final phase is the steady state phase in which the water is filtered through the filtration membrane. The water, rid of the soluble compounds by bacteria at the aeration membrane was filtered in a 0.04 pm diameter pore size membrane to remove remaining bacteria. This resulted in water of reusable quality, more specifically adhering to reuse standard for non-limited unpotable water reuse of 10 mg BOD5 L'¹ by the World Health Organization.

It was however observed that the effectiveness of scouring was strongly correlated to the ORP in the reactor (Figure 6), so that a low ORP resulted in a lower amount of scoured off biomass. On the other hand, at a higher ORP setpoint, more suspended material remained in solution and would result in lower oxygen transfer efficiency. Therefore, an ORP setpoint of 0 mV was adhered to during operation to initiate biofilm management and scouring according to the control strategy depicted in Figure 5.

However, when the effectiveness of scouring was observed to be less than expected, e.g. when a MLSS concentration of 1 g L'¹ was observed after 1 minute, when a setpoint of 2 g L'¹ was targeted, the scouring duration was increased from one to two minutes at a scouring event (as depicted in Figure 6 and 11).

At another event, the MLSS increased significantly above the targeted MLSS setpoint (3 g instead of 2 g L'¹), when due to a lower loading rate, no scouring and wasting was triggered for two days. As a response, the wasting flowrate per scouring event was automatically increased to reduce the MLSS and to achieve the set SRT target of 4 days. However, when the MLSS after scouring then reduced to 1 g L’¹, the setpoint wasting flowrate was reversed.

The MLSS reattachment efficiency is contingent to the amount of biomass in the reactor and the colloidal materials in the influent. Therefore, a good reattachment efficiency indicates better filterability, since the colloidals enhance clogging/fouling of the filtration membrane. Therefore, when the targeted re-attachment efficiency is not reached within 30 minutes, the aeration membranes have to be scoured despite not reaching the ORP setpoint, to prevent the colloidals from clogging the filtration membranes.

The present invention is not to be limited in scope by the specific embodiments described herein. Indeed, various modifications of the invention in addition to those described herein will become apparent to those skilled in the art from the foregoing description and the accompanying figures. Such modifications are intended to fall within the scope of the appended claims. It is further to be understood that all values are approximate and are provided for description.

Patents, patent applications, publications, product descriptions, and protocols are cited throughout this application, the disclosures of which are incorporated herein by reference in their entireties for all purposes.

Claims

1 . A water treatment, purification, and/or filtration system comprising

(a) a first module comprising one or more aeration membrane;

(d) means for determining the oxidative status of water;

2. The water treatment, purification, and/or filtration system according to claim 1 , wherein said means for determining the oxidative status of water comprise an oxidation-reduction potential (ORP) sensor, a dissolved oxygen (DO) sensor, and/or a nitrate and/or nitrite sensor.

3. The water treatment, purification, and/or filtration system according to any of claims 1 to

2, wherein said one or more aeration membrane comprises one or more hollow fiber membrane or one or more flat plate membrane.

4. The water treatment, purification, and/or filtration system according to any of claims 1 to

3, wherein said one or more aeration membrane comprises a biofilm.

5. The water treatment, purification, and/or filtration system according to any of claims 1 to

4, wherein said first module comprises a membrane-aerated biofilm reactor (MABR).

6. The water treatment, purification, and/or filtration system according to any of claims 1 to

5, wherein said one or more filtration membrane comprises one or more flat plate inner permeate channel (I PC) membrane.

7. The water treatment, purification, and/or filtration system according to any of claims 1 to

6, wherein said one or more filtration membrane comprises one or more microfiltration membrane and/or one or more ultrafiltration membrane.

8. The water treatment, purification, and/or filtration system according to any of claims 1 to

7, wherein said second module comprises a membrane bioreactor (MBR).

9. The water treatment, purification, and/or filtration system according to any of claims 1 to

8, wherein said first module and said second module are configured to allow water to recirculate (for instance in a closed loop) between said first module and said second module.

10. The water treatment, purification, and/or filtration system according to any of claims 1 to

9, wherein said means for scouring said one or more aeration membrane and optionally said means for scouring said one or more filtration membrane are configured to be active upon reaching a predetermined oxidative status threshold of the water.

11 . The water treatment, purification, and/or filtration system according to any of claims 1 to

10, wherein said means for scouring said one or more aeration membrane and optionally said means for scouring said one or more filtration membrane are configured to be inactive as long as a predetermined oxidative status threshold of said water is not reached.

12. The water treatment, purification, and/or filtration system according to claim 10 or 11 , wherein said predetermined oxidative status threshold is dynamically adapted based on the average time to reach a predetermined suspended particulate material concentration after initiation of one or more previous scouring events.

13. The water treatment, purification, and/or filtration system according to any of claims 1 to 12, wherein said means for scouring said one or more aeration membrane and optionally said one or more filtration membrane are configured to be active at least until a predetermined suspended particulate material concentration is reached.

14. The water treatment, purification, and/or filtration system according to claim 13, wherein said predetermined suspended particulate material concentration is dynamically adapted based on the average maximum suspended particulate material concentration during or after one or more previous scouring events.

15. The water treatment, purification, and/or filtration system according to any of claims 1 to 14, wherein said means for scouring said one or more aeration membrane and optionally said one or more filtration membrane are configured to be activated if a predetermined suspended particulate material concentration reduction is not reached during a predetermined time frame after a previous scouring event.

16. The water treatment, purification, and/or filtration system according to claim 15, wherein said predetermined suspended particulate material concentration reduction is dynamically adapted based on the average maximum suspended particulate material concentration during or after one or more previous scouring events.

17. The water treatment, purification, and/or filtration system according to any of claims 1 to 16, wherein said means for scouring said one or more aeration membrane and optionally said one or more filtration membrane are configured to be activated if a predetermined suspended particulate material concentration increase is not reached during a predetermined time frame after initiation of a previous scouring event.

18. The water treatment, purification, and/or filtration system according to claim 17, wherein said predetermined suspended particulate material concentration increase is dynamically adapted based on the average maximum suspended particulate material concentration during or after one or more previous scouring events.

19. The water treatment, purification, and/or filtration system according to any of claims 1 to

18, wherein said means for scouring said one or more aeration membrane and optionally said one or more filtration membrane are configured to be activated for a predetermined amount of time.

20. The water treatment, purification, and/or filtration system according to any of claims 1 to

19, wherein said means for scouring said one or more aeration membrane and optionally said means for scouring said one or more filtration membrane are configured to be activated for a time ranging from 1 minute to 10 minutes, preferably ranging from 2 minutes to 8 minutes, such as for 5 minutes.

21 . The water treatment, purification, and/or filtration system according to any of claims 1 to

20, wherein said means for scouring said one or more aeration membrane and optionally said means for scouring said one or more filtration membrane are configured to be active if oxidation-reduction potential (ORP) of said water is at most +50 mV, preferably at most +10 mV, more preferably at most 0 mV, such as at most -10 mV or at most -50 mV, or at most -200 mV, preferably as determined with an Ag/AgCI reference electrode with an electrolyte solution of 4M KCI.

22. The water treatment, purification, and/or filtration system according to any of claims 1 to 21 , wherein said means for scouring said one or more aeration membrane and said means for scouring said one or more filtration membrane are means for air scouring.

23. The water treatment system according to any of claims 1 to 22, further comprising means to determine the suspended particulate material concentration of water.

24. The water treatment, purification, and/or filtration system according to claim 23, wherein said means to determine the suspended particulate material such as floc concentration of water comprise a total suspended solids (TSS) sensor, a turbidity sensor, or an optical density sensor.

25. The water treatment, purification, and/or filtration system according to any of claims 1 to

24, further comprising means to determine the pH of water.

26. The water treatment, purification, and/or filtration system according to any of claims 1 to

25, wherein said particulate material is floc and/or biomass.

27. The water treatment, purification, and/or filtration system according to any of claims 1 to

26, further comprising a water to be treated influent conduit and a treated water effluent conduit.

28. The water treatment, purification, and/or filtration system according to any of claims 1 to

27, further comprising aerobic microorganisms.

29. The water treatment, purification, and/or filtration system according to any of claims 1 to

28, further comprising one or more pump, compressor, and/or blower.

30. The water treatment, purification, and/or filtration system according to any of claims 1 to

29, comprising a circulation pump, configured to effect circulation of water between the one or more aeration membrane and the one or more filtration membrane.

31 . The water treatment, purification, and/or filtration system according to any of claims 1 to

30, comprising one or more scouring compressor or blower, configured to effect scouring of the one or more aeration membrane and the one or more filtration membrane.

32. The water treatment, purification, and/or filtration system according to any of claims 1 to

31 , comprising a wasting pump, configured to remove suspended particulate material, in particular floc from the water treatment system.

33. The water treatment, purification, and/or filtration system according to any of claims 1 to

32, comprising an extraction pump, configured to remove treated water from the water treatment system (through the one or more filtration membrane(s)).

34. The water treatment, purification, and/or filtration system according to any of claims 1 to

33, comprising an influent pump, configured to introduce water to be treated in the water treatment system.

35. The water treatment, purification, and/or filtration system according to any of claims 1 to

34, comprising an aeration compressor or blower, configured to effect aeration of the water through the one or more aeration membrane.

36. The water treatment, purification, and/or filtration system according to any of claims 1 to

35, wherein said water is wastewater, such as wastewater that did or did not undergo one or more prior treatment steps.

37. The water treatment, purification, and/or filtration system according to any of claims 1 to

36, the prior treatment of the water comprises one or more physical, chemical and/or biological processes, such as anaerobic digestion.

38. The water treatment, purification, and/or filtration system according to any of claims 1 to

37, wherein said water is grey water, black water and/or yellow water, and/or wastewater from household, office, and/or industrial or agricultural activities.

39. The water treatment, purification, and/or filtration system according to any of claims 1 to

38, configured to aerate water through at least the one or more aeration membrane and filter water through the one or more filtration membrane; wherein the one or more aeration membrane and optionally the one or more filtration membrane are configured to be scoured upon reaching a predetermined oxidative status threshold of the water, resulting in the water containing suspended particulate material, such as floc.

40. The water treatment, purification, and/or filtration system according to claim 39, configured to remove at least part of the suspended particulate material, such as floc, if the suspended particulate material, such as floc, concentration exceeds a predetermined suspended particulate material, such as floc, concentration threshold.

41 . The water treatment, purification, and/or filtration system according to claim 40, wherein said predetermined suspended particulate material concentration is dynamically adapted based on the average maximum suspended particulate material concentration during or after one or more previous scouring events.

42. The water treatment, purification, and/or filtration system according to claim 40, wherein said predetermined suspended particulate material concentration is dynamically adapted based on a preset slurry residence time (SRT).

43. The water treatment, purification, and/or filtration system according to any of claims 1 to

42, configured to remove at least part of the particulate material, such as floc during and/or after scouring the one or more aeration membrane and optionally the one or more filtration membrane.

44. The water treatment, purification, and/or filtration system according to any of claims 1 to

43, configured to remove at least part of the particulate material, such as floc until a threshold oxidative status in said water is reached.

45. The water treatment, purification, and/or filtration system according to any of claims 1 to

44, configured to remove at least part of the particulate material, such as floc until a threshold particulate material, such as floc content in said water is reached or until a threshold particulate material, such as floc content reduction in said water is reached.

46. The water treatment, purification, and/or filtration system according to any of claims 1 to

45, wherein aeration is done by air, oxygen-enriched air, or oxygen.

47. The water treatment, purification, and/or filtration system according to any of claims 1 to

46, further comprising means for bubble aeration.

48. A method of water treatment, purification, and/or filtration, comprising in a water treatment, purification, and/or filtration system according to any of claims 1 to 47 aerating water through the one or more aeration membrane and filtering the water through the one or more filtration membrane; wherein when a first predetermined oxidative status threshold of the water is achieved the one or more aeration membrane and optionally the one or more filtration membrane are scoured.

49. The method according to claim 48, wherein said one or more aeration membrane and optionally the one or more filtration membrane are scoured until a second predetermined oxidative status is reached.

50. The method according to claim 48, wherein said one or more aeration membrane and optionally the one or more filtration membrane are scoured until a predetermined suspended particulate material concentration is reached.

51. The method according to any of claims 48 to 50, wherein said first and/or second predetermined oxidative status threshold is dynamically adapted based on the average time to reach a predetermined suspended particulate material concentration after initiation of one or more previous scouring events.

52. The method according to claim 50 or 51 , wherein said predetermined suspended particulate material concentration is dynamically adapted based on the average maximum suspended particulate material concentration during or after one or more previous scouring events.

53. The method according to any of claims 48 to 52, wherein said one or more aeration membrane and optionally said one or more filtration membrane are scoured if a predetermined suspended particulate material concentration reduction is not reached during a predetermined time frame after a previous scouring event.

54. The method according to claim 53, wherein said predetermined suspended particulate material concentration reduction is dynamically adapted based on the average maximum suspended particulate material concentration during or after one or more previous scouring events.

55. The method according to any of claims 48 to 54, wherein said means for scouring said one or more aeration membrane and optionally said one or more filtration membrane are configured to be activated if a predetermined suspended particulate material concentration increase is not reached during a predetermined time frame after initiation of a previous scouring event.

56. The method according to claim 55, wherein said predetermined suspended particulate material concentration increase is dynamically adapted based on the average maximum suspended particulate material concentration during or after one or more previous scouring events.

57. The method according to any of claims 48 to 56, further comprising removing at least part of the suspended particulate material, such as floc, obtained after scouring.

58. The method according to claim 57, configured to remove at least part of the suspended particulate material, such as floc, if the suspended particulate material, such as floc, concentration exceeds a predetermined suspended particulate material, such as floc, concentration threshold.

59. The method according to claim 57 or 58, wherein said predetermined suspended particulate material concentration is dynamically adapted based on the average maximum suspended particulate material concentration during or after one or more previous scouring events.

60. The method according to claim 57 or 58, wherein said predetermined suspended particulate material concentration is dynamically adapted based on a preset slurry residence time (SRT).

61. The method according to any of claims 48 to 60, wherein the oxidative status of said water is periodically or continuously measured.

62. The method according to any of claims 48 to 61 , wherein the rate of influent water approximates or is equal to the rate of effluent water.

63. The method according to any of claims 48 to 62, wherein during scouring recirculation of the water in the system is prevented or interrupted and/or filtration is prevented or interrupted.