HK1247179A1

HK1247179A1 - A method of improving sludge removal and maintaining effluent quality in an activated sludge wastewater treatment process

Info

Publication number: HK1247179A1
Application number: HK18106376.1A
Authority: HK
Inventors: G．罗伯特．怀特曼; G．羅伯特．懷特曼
Original assignee: G．罗伯特．怀特曼
Priority date: 2018-05-17
Filing date: 2018-05-17
Publication date: 2018-09-21

Description

Method for improving sludge removal and maintaining discharge quality in activated sludge wastewater treatment processes

The present application is a divisional application of chinese patent application No.201180015287X entitled "system and method for reducing sludge generated by a wastewater treatment facility" filed as 2011, 3, and 15.

Background

Wastewater produced by municipal and industrial water is typically collected and transported in designated routes to treatment facilities for removal of various physical, chemical and biological contaminants before being discharged into a receiving body of water. Many public and private processing facilities employ physical and biological processes in order to achieve the necessary treatment. Physical methods, including screening, grinding and physical settling treatments, are effective in removing larger and heavier solids from wastewater. However, lighter, smaller solids and other soluble contaminants in the wastewater cannot be removed by physical methods. For these contaminants, biological treatment methods such as activated sludge and trickling filters are generally used.

In recent years, the pollutant discharge regulations of municipal wastewater treatment systems have become more and more stringent. In response to this situation, many cities have adopted new wastewater treatment systems or have modified existing systems to reduce pollutant emissions. The contaminants may be in a variety of forms, the most common of which are Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), ammonia, total nitrogen, nitrates, nitrites, and phosphorous.

Biological treatment systems, such as conventional activated sludge systems and membrane biological reactors, are one method of reducing pollutants in wastewater influent. The term "influent" refers to raw (untreated) or partially treated wastewater or other liquid that flows into a reservoir, basin, treatment process, treatment plant or treatment facility. The biological treatment system is designed and operated so as to maintain a sufficient amount of activated sludge so that the water treated by the system has a substantially reduced pollutant load. The net production of waste activated sludge is related to the Solids Retention Time (SRT) of the system by weight or mass of the waste activated sludge produced. The minimum SRT required to treat a variety of contaminants under a variety of conditions is well known. Conventional activated sludge systems retain activated sludge by employing a settling or clarification device and are able to maintain sufficient SRT to treat contaminants, provided that the flow rate of activated sludge concentrate to the settling tank or clarification device and the settling performance of the activated sludge are within reasonable limits set by design parameters, depending on the area of the settling tank or clarification device and the characteristics of the activated sludge. Membrane bioreactor systems retain activated sludge by using a membrane filtration device and can operate well at significantly higher activated sludge concentrations than is typical of conventional activated sludge systems, but have limited capacity in treating occasional high flow rate conditions.

When the pollutant load or hydraulic capacity (hydralic capacity) reaches a limit, the treatment facility will be at risk: violations of the permitted limits, the possibility of federal or state governments taking mandated measures, and the growth of residents' living standards and industries within the collection system service area of a processing plant are limited or hindered. Generally, the demand for increased hydraulic load can be met by physically expanding the wastewater treatment facility. However, physical expansion is expensive and often requires the use of additional land, which may not be available in the immediate vicinity of existing facilities, particularly in large cities.

Therefore, there is a need to find a way to increase the volume or mass loading and hydraulic capacity of contaminants without the need for physical expansion of the plant. Compared with the prior sludge treatment method, the invention has the remarkable advantages that: by adding a biological fermentation device to an existing physical installation, the volume load of contaminants can be significantly increased. In addition, the invention also has the following characteristics and advantages: the improved sludge process is capable of producing biological sludge with improved settling characteristics. The improved settling characteristics allow for increased hydraulic loading without the need to increase the size of the physical elements of the activated sludge system, since net sludge waste and/or production is lower. The other advantage is that: operating costs, such as chemical, human, energy and transportation costs, are reduced because the amount of biological sludge to be handled and disposed of in the sludge treatment process is small, and biological sludge typically accounts for 40-50% of the operating costs of wastewater treatment facilities. For the same reason, new wastewater treatment plants can be constructed on a smaller scale, wherein the demand for sludge treatment facilities is greatly reduced and therefore their capital costs are lower than those of known systems. For existing wastewater treatment systems that require upgrading, it is possible that capital expansion may be curtailed or the need for partial or full expansion delayed. In addition, the time taken to discard the biological sludge from the start of the activated sludge process to the aerobic or anaerobic digestion unit can be extended by 25-50%, and the time taken from the process to the dewatering step (such as a drying bed, filter press, or centrifuge) can be extended by 25-50%. These excess times represent: less manpower, less equipment, less power supply, and less chemical usage are required.

Disclosure of Invention

The present invention relates to a method for improving the removal of sludge and maintaining the quality of the discharge. The method comprises the following steps: introducing an incoming wastewater stream to a treatment facility, said wastewater stream having a flow rate of at least 20,000 gallons per day; said incoming wastewater stream containing at least 50mg/L solids and 100mg/L BOD; removing solids and BOD from the incoming wastewater stream in the treatment facility, thereby providing a final effluent stream; the solids in the final effluent stream are less than 10% of the solids in the wastewater stream and the BOD is less than 10% of the BOD in the wastewater stream; the removal of solids and BOD produces less than about 0.25 pounds of secondary sludge per pound of BOD reduced. In the process, the incoming wastewater stream may contain at least about 100mg/L solids and 200mg/L BOD, and the removed solids may be less than about 0.25 pounds of secondary sludge per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 100mg/L solids and 400mg/L BOD, and the removed solids may be less than about 0.25 pounds of secondary sludge per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 50mg/L solids and 100mg/L BOD, and the removed solids may be less than about 0.125 pounds of secondary sludge per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 100mg/L solids and 200mg/L BOD, and the removed solids may be less than about 0.125 pounds of secondary sludge per pound of BOD removed.

In another embodiment, the invention relates to a method of improving sludge removal and maintaining discharge quality. The method comprises the following steps: introducing an incoming wastewater stream to a treatment facility, said wastewater stream having a flow rate of at least 20,000 gallons per day; said incoming wastewater stream containing at least 50mg/L solids and 100mg/L BOD; removing solids and BOD from the incoming wastewater stream in the treatment facility, thereby providing a final effluent stream; the solids in the final effluent stream are less than 10% of the solids in the wastewater stream and the BOD is less than 10% of the BOD in the wastewater stream; the removal of solids and BOD produces less than about 0.25 pounds of biological sludge per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 100mg/L solids and 200mg/L BOD, and the removed solids may be less than about 0.25 pounds of biological sludge per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 100mg/L solids and 400mg/L BOD, and the removed solids may be less than about 0.25 pounds of biological sludge per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 50mg/L solids and 100mg/L BOD, and the removed solids may be less than about 0.125 pounds of biological sludge per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 100mg/L solids and 200mg/L BOD, and the removed solids may be less than about 0.125 pounds of biological sludge per pound of BOD removed.

In another embodiment, the invention relates to a method of improving sludge removal and maintaining discharge quality. The method comprises the following steps: introducing an incoming wastewater stream to a treatment facility, said wastewater stream having a flow rate of at least 20,000 gallons per day; said incoming wastewater stream containing at least 50mg/L solids and 100mg/L BOD; removing solids and BOD from said incoming wastewater stream in said treatment facility, thereby providing a first final effluent stream; the solids in the first final effluent stream are less than 10% of the solids in the wastewater stream and BOD is less than 10% of the BOD in the wastewater stream; the wastewater fluid is treated by adding a treatment batch (treatment batch) from a biological fermentation unit, whereby pounds of sludge removed is reduced by at least about 10% without an increase in the amount of solids and BOD in the final effluent fluid. In the method, the treatment ingredients may be added to the anaerobic digestion unit, the equalization tank, and/or the primary clarification unit. In this process, pounds of sludge removed can be reduced by at least about 25% without an increase in the amount of solids and BOD in the final effluent stream. In this process, pounds of sludge removed can be reduced by at least about 50% without an increase in the amount of solids and BOD in the final effluent stream.

In another embodiment, the invention relates to a method of improving sludge removal and maintaining discharge quality. The method comprises the following steps: introducing an incoming wastewater stream to a treatment facility, said wastewater stream having a flow rate of at least 20,000 gallons per day; said input wastewater stream containing at least 50mg/L of biosolids and 100mg/L of BOD; removing biological solids and BOD from the incoming wastewater stream in the treatment facility, thereby providing a final effluent stream; the biological solids in the final discharge stream are less than 10% of the biological solids in the wastewater stream and BOD is less than 10% of the BOD in the wastewater stream; the removal of solids and BOD produces less than about 0.25 pounds of biosolids per pound of BOD removed. In this method, the sludge may be primary sludge, biological sludge, and/or the sludge may comprise both primary sludge and biological sludge. In the process, the incoming wastewater stream may contain at least about 100mg/L solids and 200mg/L BOD, and the removed solids may be less than about 0.25 pounds of biological solids per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 100mg/L solids and 400mg/L BOD, and the removed solids may be less than about 0.25 pounds of biological solids per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 50mg/L solids and 100mg/L BOD, and the removed solids are less than about 0.125 pounds of biosolids per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 100mg/L solids and 200mg/L BOD, and the removed solids may be less than about 0.125 pounds of biological solids per pound of BOD removed.

In additional embodiments, the present invention relates to a method of improving sludge removal and maintaining discharge quality. The method comprises the following steps: introducing an incoming wastewater stream to a treatment facility, said wastewater stream having a flow rate of at least 20,000 gallons per day; said input wastewater stream contains at least 50mg/L solids or 100mg/L BOD; removing solids and BOD from the incoming wastewater stream in the treatment facility, thereby providing a final effluent stream; the solids in the final effluent stream are less than 10% of the solids in the wastewater stream and the BOD is less than 10% of the BOD in the wastewater stream; the removal of solids and BOD produces less than about 0.25 pounds of secondary sludge per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 100mg/L solids and 200mg/L BOD, and the removed solids may be less than about 0.25 pounds of secondary sludge per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 100mg/L solids and 400mg/L BOD, and the removed solids may be less than about 0.25 pounds of secondary sludge per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 50mg/L solids and 100mg/L BOD, and the removed solids may be less than about 0.125 pounds of secondary sludge per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 100mg/L solids and 200mg/L BOD, and the removed solids may be less than about 0.125 pounds of secondary sludge per pound of BOD removed.

In another embodiment, the invention relates to a method of improving sludge removal and maintaining discharge quality. The method comprises the following steps: introducing an incoming wastewater stream to a treatment facility, said wastewater stream having a flow rate of at least 20,000 gallons per day; said input wastewater stream contains at least 50mg/L solids or 100mg/L BOD; removing solids and BOD from the incoming wastewater stream in the treatment facility, thereby providing a final effluent stream; the solids in the final effluent stream are less than 10% of the solids in the wastewater stream and the BOD is less than 10% of the BOD in the wastewater stream; the removal of solids and BOD produces less than about 0.25 pounds of biological sludge per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 100mg/L solids and 200mg/L BOD, and the removed solids may be less than about 0.25 pounds of biological sludge per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 100mg/L solids and 400mg/L BOD, and the removed solids may be less than about 0.25 pounds of biological sludge per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 50mg/L solids and 100mg/L BOD, and the removed solids may be less than about 0.125 pounds of biological sludge per pound of BOD removed. In the process, the incoming wastewater stream may contain at least about 100mg/L solids and 200mg/L BOD, and the removed solids may be less than about 0.125 pounds of biological sludge per pound of BOD removed.

Drawings

FIG. 1 is a flow diagram of a conventional activated sludge process.

FIG. 2 is a schematic view of a conventional wastewater treatment process.

FIG. 3 is a diagram illustrating an exemplary wastewater treatment sequence and process.

FIG. 4 is a diagram illustrating an exemplary wastewater treatment sequence and process.

Detailed Description

Various embodiments of the present invention provide systems and methods for treating wastewater. Many embodiments of the present invention are capable of receiving influent that exceeds one or more environmental standards and discharging effluent that meets current environmental standards, including limits on BOD, COD, TSS, ammonia, nitrate, nitrite, total nitrogen, and phosphorous levels. These environmental emission standards are controlled by or by the National Pollutant Discharge Elimination System (NPDES). Aspects of the present invention may be selected to maximize process efficiency and minimize operating costs during "normal" operation, but still achieve acceptable emission quality using the same system, even during high input periods.

In particular, the present invention relates to a wastewater treatment process wherein the net amount of waste or produced biological sludge is reduced.

SUMMARY

The practice of the present invention employs, unless otherwise indicated, conventional techniques in the art of wastewater treatment that are conventional in the art for class one registered operators or class a registered operators, or engineers with a degree of environmental engineer scholarness. The definitions of these techniques and technical terms are explained fully in the literature, for example, with respect to operator credentials, see Operation of Water Treatment Plants Manual, A Field Study tracking program, 4 th edition, volumes 1 and 2, California State university, Sacchara-Gate Town, 1993; IndustrialWaste Treatment, A Field Study tracking Program, Calif. State university, Sacchara, Tou, 1991; advanced Water Treatment, A Field Study tracking Program, 2 nd edition, California State university, Sacchara Tour, 1993; and Operation and Maintenance WaterCollection Systems, A Field Study tracking Program, 4 th edition, volumes 1 and 2, California State university, Sacchara, Town.1993.

The wastewater may be treated near a location where the wastewater is produced, such as a septic tank, a biological filter, or an aerobic treatment system, or the wastewater may be collected and transported to a wastewater treatment plant through a pipe network and pumping stations (referred to as collection systems). The collection and treatment of wastewater typically follows local, state and federal government regulations and standards. Wastewater from industrial sources often requires the use of specific treatment processes.

Generally, wastewater treatment comprises three stages, referred to as primary, secondary and tertiary treatment.

The primary or settling treatment/stage comprises: the influent wastewater is temporarily held in a static tank where heavy solids settle to the bottom while fats, oils, greases and lighter solids float to the surface. The sediment and floaters are removed and the remaining liquid may be discharged or subjected to secondary treatment.

The term "influent" refers to: raw (untreated) or partially treated wastewater or other liquids that flow into a reservoir, basin, treatment process or treatment plant or facility.

In the primary stage, the wastewater flows through a large tank commonly referred to as a "primary clarifier" or "primary settling tank". The term "clarifier" refers to a settling tank or sedimentation tank, which is a tank or pond that holds the wastewater for a period of time during which heavier solids settle to the bottom and lighter materials float to the surface of the water. The tank is large enough so that the sludge can settle and floaters such as grease and oil can rise to the surface and be skimmed off. The main purpose of the primary settling stage is to produce a generally homogeneous liquid that can be biologically treated and a sludge that can be treated or processed separately. The primary settling tank is usually equipped with mechanically driven scraper members which continuously drive the collected sludge to a storage device located at the bottom of the tank, from where it is pumped to further sludge treatment stages.

The term "sludge" includes "primary sludge", "secondary sludge" or "biological sludge", and other "solids", which terms are used interchangeably depending on context, all referring to excess biomass produced by biodegradation of organic matter during secondary (biological) treatment.

The term "primary sludge" refers to the semi-liquid waste resulting from settling in a primary treatment, without additional treatment. Which typically includes organic matter, paper, fecal matter/solids that are settled and removed from the bottom of the primary clarifier or fished out of the pretreatment or equalization tank. The primary sludge may also include secondary sludge if the co-settling of secondary sludge and primary sludge is performed in the primary clarifier.

The term "secondary sludge" or "biological sludge" refers to excess biomass produced by biodegradation of organic matter during secondary (biological) treatment. Secondary sludge includes activated sludge, mixed sludge and chemically precipitated sludge.

The term "solids" refers to primary sludge, secondary sludge, or both.

The term "biosolids" refers to the primary solid product produced by a wastewater treatment process.

The primary sludge and the secondary sludge are combined by the operation of concentrating/reducing the solid by an anaerobic digestion method. Aerobic treatment is usually secondary treatment.

Sludge in the wastewater is typically removed to maintain solids accumulation in the biological process. After the sludge is removed, a sludge treatment process (which may take various forms from the initial treatment) may be performed using aerobic or anaerobic digestion to reduce the volume of the sludge, followed by a concentration step using a chemical agent (flocculant or polymer) in machinery (e.g., centrifuge, belt press) to be finally disposed of by land application, incineration, and landfill. In activated sludge plants, the amount of sludge waste and the subsequent treatment process are of great importance for maintaining the food to microorganism ratio (F: M ratio), since the F: M ratio is the main parameter for determining and controlling the quality of the emissions. The term "F: M ratio" refers to the ratio of food to microorganisms, which is a measure of the food provided to the bacteria in the aeration tank.

Secondary treatment removes dissolved and suspended biological material. Typically, secondary treatment is carried out by endogenous aquatic microorganisms in a managed habitat, i.e. a biological waste treatment system. Secondary treatment requires a separation process to remove microorganisms from the treated water prior to discharge or tertiary treatment.

Sometimes, a three-stage process is defined as any process other than the one-stage and two-stage processes. Sometimes, the treated water is chemically or physically disinfected (e.g., by lagoons and microfiltration) prior to discharge into a stream, river, bay, lagoon or wetland, or the treated water may be used to irrigate a golf course, bouillon or park. If the treated water is sufficiently clean, it can also be used to replenish ground water or for agricultural applications.

Generally, influent wastewater may also be pretreated. Pretreatment removes materials such as large objects that can be easily collected in raw wastewater before they damage or clog the pumps and skimmer units of the primary treatment clarifier. In modern plants serving a large population, it is most common to use an automated mechanical raked bar screen for the pre-treatment, whereas in smaller or less modern plants manual cleaning of the screen is possible. The step of the raking action of a mechanical grizzly is typically determined based on the accumulation and/or flow rate on the grizzly. The resulting solid is collected and then disposed of in landfills or by incineration.

The pre-treatment may also comprise sand or gravel channels or chambers where care is taken to control the flow rate of the influent wastewater stream so that sand, gravel and stones can settle.

After the tertiary treatment, the accumulated sludge must be treated and disposed of in a safe and efficient manner. The purpose of digestion is to reduce the amount of organic matter and the number of pathogenic microorganisms present in the solids. The most common alternative treatments include anaerobic digestion, aerobic digestion and composting. Incineration may also be used.

The choice of wastewater solids treatment method depends on the amount of solids produced and other site-specific conditions. However, in general, compost is most commonly used for smaller scale applications, followed by aerobic digestion, and finally anaerobic digestion for larger scale municipal applications.

Anaerobic digestion is a bacterial treatment performed without the use of oxygen. The treatment may be either a pyrodigestion, in which the sludge is fermented in a tank at a temperature of 55 c, or a mesophilic digestion carried out at a temperature of about 36 c. Although allowing shorter residence times (so that smaller ponds can be used), pyrodigestion is more expensive in terms of energy consumption for heating the sludge.

One of the main features of anaerobic digestion is the production of biogas (of which the most useful component is methane), which can be used for power generation by generators and/or for boiler heating.

Aerobic digestion is a bacterial treatment that occurs in the presence of oxygen. Under aerobic conditions, the bacteria rapidly consume the organic material and convert it to carbon dioxide. The operating costs for aerobic digestion are significant because the blowers, pumps and motors required to add oxygen to the process consume energy and are costly even with the more recent advent of stone fiber filtration technology using natural gas streams for oxidation. Aerobic digestion can also be achieved by oxidizing the sludge using jet aeration devices, which are also costly, but less costly than conventional processes.

Composting is also an aerobic process which involves mixing the sludge with a carbon source such as sawdust, straw or wood chips. In the presence of oxygen, the bacteria digest the wastewater solids and the added carbon source while generating a large amount of heat.

Incineration of sludge is less common because it involves air emission issues and burning low heating value sludge and evaporating residual moisture requires the use of additional fuel (typically natural gas or fuel oil). Step-by-step multi-hearth incinerators and fluidized-bed incinerators with high residence times are the most common systems for burning waste water sludge. The co-firing approach is occasionally employed in municipal waste-to-energy conversion plants, which is less expensive given that the facilities for solid waste are already present and do not require the use of auxiliary fuels.

When liquid sludge is produced, additional treatment may be required to render the sludge suitable for ultimate disposal. Typically, the sludge is subjected to thickening (dewatering) to reduce the transport volume for off-site disposal. No process can completely eliminate the need for disposing of biosolids. However, some cities employ additional steps to superheat the wastewater sludge and convert the "cake" into small particles rich in nitrogen and other organic matter and use it as fertilizer. Such products can then be sold to local farmers and pastures as soil conditioners or fertilizers, thereby reducing the space required to landfill these sludges. This removed liquid (referred to as filtrate) is typically reintroduced into the wastewater process.

There are different types of wastewater treatment systems and processes. An example of a wastewater treatment system is the activated sludge process (flow diagram shown in fig. 1). Typically, during the pre-treatment stage, the influent is first screened to remove rhizomes, rags, tanks and large debris (which may then be hauled to a landfill or possibly ground and returned to the in-plant stream). The sand and grit in the influent is then removed in a grit removal step and the wastewater is pre-aerated to freshen the wastewater and aid in oil removal. The influent then passes through a flow meter for measuring and recording the flow rate. After pretreatment, the influent is subjected to a primary treatment, including settling and flotation, to remove settleable and floatable materials. After the primary treatment, the wastewater is subjected to a secondary treatment (also known as biological treatment) to remove soluble or dissolved organic matter by biodegradation, while, in the event of some biodegradation occurring over time, suspended solids are removed by entrainment of floes. After the secondary treatment, the wastewater enters a tertiary treatment, where the wastewater is disinfected to kill pathogenic microorganisms, and the wastewater is generally aerated again before the effluent is discharged.

Fig. 2 shows another example of a wastewater treatment process. Specifically, it is an example of a pure oxygen system. A pure oxygen system is an improvement over the activated sludge process. The main difference is the method of providing dissolved oxygen to the activated sludge. In other activated sludge processes, air is compressed and released under water, creating an air-water interface that transfers oxygen to the water (dissolved oxygen). If compressed air is not used, a surface aerator is used to agitate the water surface to drive air into the water, thereby creating an oxygen transfer. In a pure oxygen system, the only substantial differences are: the use of surface aerators to release or drive pure oxygen into the water below the surface rather than air and the aerators are covered. In this process, the influent undergoes primary clarification. As shown in fig. 2, the influent is pretreated and then passed through a primary clarifier, a pure oxygen reactor, and a secondary clarifier. The effluent may be contacted with chlorine gas and discharged into the contained water. The sludge may be returned to the pure oxygen reactor or combined with thickened sludge from the primary clarifier and passed through the primary and secondary anaerobic digesters. The solids may then be subjected to a dewatering process.

Other wastewater treatment processes are known in the art and may be used in accordance with the methods of the present invention.

Method for treating waste water

In one embodiment, the invention is a method of treating wastewater wherein the net amount of sludge discarded or produced is reduced in the method.

In this process, a biological fermentation system, described in more detail in U.S. patent application publication No.2003/0190742, the entire contents of which are incorporated herein in their entirety, is located on site at the site of the wastewater treatment facility.

The in-situ system is used to grow microorganisms at a location or site where contaminated wastewater is located and generally includes a main basin, a water inlet, a treatment ingredient outlet, a mixing device, and a temperature control device. Nutrients, water and an inoculum containing microorganisms are placed in the in situ system. The inoculum is grown in the in situ system to provide a treatment formulation comprising an increased number of microorganisms. The treatment formulation, which at least partially comprises the microorganisms, is then applied directly to the contaminated wastewater such that the microorganisms are not isolated, concentrated, or lyophilized between the growing step and the applying step. The microorganisms reduce the contaminants in the contaminated wastewater. In large activated sludge plants or single pass lagoons, the treatment batch may be transferred using storage tanks, wherein the treatment batch may be diluted to obtain a larger volume for pumping and dosing purposes, thereby continuously discharging the treatment batch.

Importantly, the use of an in situ biofermentation system enables sufficient and repeated inoculation of functional microorganisms (whether exogenous or endogenous) to allow the microbial population to rapidly build up and outweigh an undesirable endogenous population, such as filamentous or zoogloea microorganisms that cause clumping. Problems such as filament or clumping can result in an increase in the overall cost of operating a wastewater treatment plant by as much as 20-25%, and there is a great commercial need to address this problem. The first part of the increased processing costs stems from: settling aids or chemicals are required to clarify the water and concentrate the biomass in the secondary clarifier. Examples of such chemicals include polymers, bentonite, alum or iron salts. The second part of the added cost stems from: the growth of filamentous or zoogles results in poor dewatering, and thus, the amount of equipment required to treat sludge and the amount of polymer used for dewatering increase, resulting in increased costs. The third part of the added cost stems from: since the operation efficiency becomes low, the manpower required increases, and the transportation cost and the disposal cost increase. Biological fermentation systems provide a process for controlling or transferring undesirable microorganisms, such as filamentous or zoogloea microorganisms that cause clumping and settling problems. Using the fermentation process to reduce or reduce the use of polymers for enhanced settling; minimizing the amount of dehydration chemicals used; and minimizing the need for sludge treatment, manpower, transportation costs, and disposal costs.

In addition, the biological fermentation process allows for an effective concentration of the desired microorganisms at the point of application sufficient to effectively treat the wastewater at the point of application. Most preferably, the inoculum is grown to a concentration of about 10⁸-10⁹Colony forming units per milliliter (cfu/ml), to achieve about 10 at the point of application³-10⁴Preferred minimal inoculation of cfu/ml.

The type of microorganism or microorganisms present in the inoculum depends on the type of wastewater to be treated. Depending on the waste water problem to be solved, the inoculum may contain a single strain or a plurality of strains. The inoculum provided may be a liquid or a dry product. The dry product is typically lyophilized or air dried. In addition, the microorganisms may be exogenous to the wastewater or endogenous microorganisms may be isolated from the wastewater being treated.

As used herein, the terms "microorganism" or "organism" are interchangeable and include fungi, yeast, bacteria and other small, biodegradable, unicellular organisms.

Preferably, sludge-reducing microorganisms (available from advanced sludge treatment Services, Inc. of Flemingin island, Florida) are used in wastewater treatment facilities where BOD removal efficiency is low, the system is overloaded, and/or in any treatment facility for wastewater treatment, to reduce the operating costs related to sludge treatment, which typically account for about 40-50% of the operating costs of any facility.

Some examples of microorganisms with specific biodegradation properties are provided in table 1.

TABLE 1

Note: spp, these species may vary; the bacillus subtilis is one of bacillus; pseudomonas putida is one of the genus Pseudomonas; CO 2₂Carbon dioxide.

Standard respirometry techniques can be used to determine which culture or manufacturer's formulation is most effective for treating a particular wastewater. The principle of respiration determination is: the activity of biomass exposed to the test substrate is measured and compared to a control containing biomass and known substrate, which gives predictable results. The substrate to be tested may range from a particular chemical or waste stream to a combined waste water. Breath-test experiments may be provided to stimulate aerobic or anaerobic environments. Typical applications of breath determinations include evaluating: the disposability of municipal and industrial wastewater; toxicity of particular waste streams or chemicals; the biodegradability of the chemical; biochemical Oxygen Demand (BOD); and Oxygen Uptake Rate (OUR).

Aerobic microorganisms use oxygen to grow and metabolize organic substrates. For aerobic microorganisms, the Oxygen Uptake Rate (OUR) is believed to be directly related to organic stabilization and thus to the ability of the formulation to biodegrade organic waste.

Breath testing equipment and treatability protocols for aerobic and anaerobic studies are available from U.S. manufacturers, such as Challenge Environmental Systems of Fayetteville, arkansas; arthur technology of Fond du Lac, Wisconsin; and Bioscience Management of bethlehem, pa. Examples of aerobic treatability studies can be found in The technical literature, such as Whiteman, G.R., TAPPIEnenvironmental Conference, "The Application of Selected microbiological formulations in The Pulp and Paper Industry", TAPPI Environmental Proceedings, first volume, p.235-; whiteman, G.R., Gwinnett Industrial Conference, "optimizing biological Processes-A Look insert The Black Box", 1995 month 4; and Whiteman, g.r., TAPPI Environmental Conference, "Improving Treatment Performance with natural bioauthmentation", TAPPI Environmental Proceedings, Vancouver, BC, 1998; the contents of these documents are incorporated herein by reference.

Once the effectiveness of each isolate, isolate and/or formulation has been compared using respirometry techniques, the best one can be selected as the inoculum for the fermentation process described herein. Ready-made cultures are available from Advanced Biofertilization Services, Inc. of Fleming island, Florida, USA.

The term "nutrient" refers to a substance required to maintain the survival of a plant or organism. The main nutrients are carbon, hydrogen, oxygen, sulfur, nitrogen and phosphorus. The nutrients include macronutrients and micronutrients. Table 2 below shows typical compositions of the microorganisms, wherein it is apparent that different microorganisms have different compositions. Microorganisms also differ in their ability to assimilate nitrogen into amino acids, which are the basic building blocks of purine or pyrimidine bases that make up proteins or ribonucleic acids (RNA) and deoxyribonucleic acids (DNA). Thus, different microorganisms have different requirements for macro (nitrogen and phosphorus) and micro (e.g. magnesium, calcium, potassium, sodium, manganese, cobalt, nickel, zinc, iron, chlorine and sulphur) nutrients to optimize the fermentation process. Information on macro-and micronutrients is found in the introduction Microbiology of Levy et al, which is incorporated herein by reference, and includes the concentration of complex nutrient-requiring (hardly proliferating) microorganisms, how to determine whether a specific micronutrient is required, and a general explanation of the effect of the nutrients.

TABLE 2

Composition (I)	Yeast	Bacteria	Zoogloea
				Carbon (C)	47.0	47.7	44.9
Hydrogen	6.0	5.7	--
				Oxygen gas	32.5	27.0	--
Nitrogen (N)	8.5	11.3	9.9
				Ash content	6.0	8.3	--
Experimental type	C₁₃H₂₀N₂O₇	C₅H₇NO	--
				Ratio of C to N	5.6:1	4.3:1	4.5:1

The active biomass is composed primarily of bacteria, most of which contain 8-15% nitrogen (most typically 12-12.5%) and 2-5% phosphorus (most typically 2.3-2.6%) in the biological treatment plant. Phosphorus is important in the formation of Adenosine Triphosphate (ATP), a substance that microorganisms store energy.

Microorganisms consist of proteins, carbohydrates, fatty substances known as lipids, or combinations of the above. In particular, proteins are used to make enzymes, which are the basis of biodegradation processes. For any particular organic substance, a series of reactions constitute a biodegradation process. Each reaction is carried out by a specific enzyme. These enzymes consist of amino acids and (sometimes) cofactors, usually metals, which constitute the reactive sites of the enzyme where biodegradation and conversion of organic matter takes place. Optimally, sufficient amounts of micronutrients are present to optimize the fermentation or biodegradation process. Micronutrients include substances such as vitamins, coenzymes, metals or inorganic compounds as desired, for example for the preparation of enzymes, coenzymes or cofactors for cell growth. For example, sulfur is a substance required for assimilation of the essential amino acids cysteine and methionine. Information on the action of such micronutrients, e.g. coenzymes, including folic acid, pantothenic acid (coenzyme A), vitamin B₁₂(Cobalamide), biotin, nicotinic acid or Nicotinamide (NAD), vitamin B₁(Thiamine), vitamin B₂(Riboflavin) vitamin B₆(pyridoxine), lipoic acid and ascorbic acid, see ABiochemistry of lbert l.lehninger, second edition, Worth publishing company, 1975, ISBN: 0-87901-047-9, and Levy et al, Introductor Microbiology, John Wiley&Sons corporation, 1973, ISBN 0-471-.

As previously mentioned, the type of microorganism(s) used in the wastewater treatment process of the present invention depends on the type of wastewater problem to be solved. The most commonly used microorganisms are bacteria, and the most commonly used are aerobic, mesophilic bacteria. Aerobic bacteria use oxygen to metabolize organic matter, measured for example by Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Organic Carbon (TOC) or Total Carbon (TC). Facultative bacteria that can be metabolized under aerobic or anaerobic conditions, or anaerobic bacteria that do not use oxygen, can also be used. In addition, bacteria were classified according to the optimal growth temperature. For thermophilic bacteria, the optimal temperature is 55-75 ℃; for mesophilic bacteria, the optimal temperature is 30-45 ℃; whereas for psychrophiles it must be at a temperature of 15-18 ℃.

The use or use of the in situ biological fermentation process and system results in a lower net sludge waste volume and/or production for any wastewater treatment facility (municipal or industrial).

A preferred wastewater treatment sequence and process according to the present invention is generally shown in figures 3 and 4. However, the method of the present invention is not limited to any particular system illustrated in the drawings or described in the foregoing detailed description, and any apparatus capable of performing the performance of the method of the present invention may be used instead.

Referring to fig. 3, the wastewater treatment method according to the present invention includes: pretreatment, primary treatment (chemical and physical treatment), secondary treatment (removal of dissolved organic matter and suspended solids), tertiary treatment, sludge disposal, and liquid disposal.

The specific treatment steps of the wastewater treatment method of the present invention are shown in FIG. 4.

The pretreatment step comprises the following steps: sieving and grit removal, homogenization and storage, and oil separation. The chemical primary treatment comprises the following steps: at least two neutralization steps, a chemical addition step, and a coagulation step. The physical primary treatment comprises the following steps: multiple flotation, sedimentation and filtration steps. Secondary treatment of the dissolved organic matter includes: activated sludge, anaerobic lagoons, trickling filters, aeration lagoons, stabilization tanks, rotating biological contact devices, membrane biological reaction devices, Sequencing Batch Reactor (SBR), and anaerobic contact devices and filters. Operations for removing suspended solids in the secondary treatment include: settling of solids, or internal aeration tanks with static circulation (SBR) or the use of membranes. The wastewater is then subjected to a three stage process comprising: coagulation and sedimentation, filtration, carbon adsorption, ion exchange and membranes. The sludge resulting from the above treatment steps can then be used for sludge treatment. In particular, the sludge may be treated with digestion or wet combustion. The sludge can be thickened (dewatered) by gravity or flotation, thereby reducing the transport volume for off-site disposal. Further, the sludge may be treated by pressure filtration, vacuum filtration, centrifugation, aeration or a dry bed. After sludge treatment, the sludge may be disposed of by incineration, sea disposal, and landfill. The treated dilute wastewater may also be discharged into receiving waters, controlled or transport discharge, sea-throwing treatment, surface application or groundwater infiltration, evaporation and incineration. The concentrated organic wastewater can be disposed of by deep well injection or incineration.

Surprisingly, wastewater treatment processes incorporating the present in situ biological fermentation systems employing sludge-reducing microorganisms result in lower net sludge waste and/or production.

Specifically, typically, for every 1 pound (lb) of BOD processed by the secondary system, 0.5 pounds of sludge is expected to be wasted and/or produced. This equates to 0.45 pounds of sludge per 1 pound of BOD entering the plant, based on the BOD load of influent and the 90% BOD removal rate typical of most biological systems.

Biological sludge formation rates vary with different wastewater compositions, for example, fats, oils and/or greases (FOG) may produce between 0.7 and 0.8 pounds of sludge per pound of BOD reduced, while chemicals such as benzene or phenol may produce as low as 0.25 pounds of sludge per pound of BOD reduced.

However, according to the method of the present invention, when a biological fermentation system (which uses sludge-reducing microorganisms as a treatment ingredient) is installed on-site at a wastewater treatment facility, 0.125 pounds of sludge is discarded and/or produced for every 1 pound of BOD treated by the secondary system. Based on the BOD load of influent and the 90% BOD removal rate typical of most biological systems, this is equivalent to 0.112 pounds of sludge per 1 pound BOD entering the plant, a value significantly lower than would be expected by one of ordinary skill in the art based on the amount of influent entering the treatment facility.

Without being bound by a particular mechanism, it is believed that the lower net sludge waste amount and/or production may be attributed to, for example, an increased number of microorganisms present in the system and may be used in a biological fermentation process as described in U.S. patent application publication No. 2003/0190742. By increasing the number of viable microorganisms in the biological system, the F: M ratio can be reduced radically, which means that more viable microorganisms eat less food. This, in turn, will allow the microorganism to use the BOD for cellular metabolism to maintain the cells rather than for cell growth. The latter reason will result in a lower amount of biosludge. Additionally or alternatively, the benefits of reducing filamentous microorganisms (in activated sludge systems) are: producing a sludge with better settling properties, which allows the biological system to carry more sludge, thereby reducing the F: M ratio and increasing SRT. M ratio reduction and SRT increase are conventional methods of reducing the net sludge waste volume, as more sludge autodigests itself in the biological system resulting in a smaller net sludge waste volume.

Examples

Example 1

Gray, city of Gray

The aim of this study was to improve the BOD treatment efficiency and hydraulic capacity of the griffith activated sludge wastewater treatment facilities, as conventional treatment systems are often overloaded daily at the design capacity.

Prior to treatment, the traditional integrated activated sludge system of griffith for wastewater treatment was designed to treat 400,000 gallons per day (gpd) of municipal wastewater and had an integrated aerobic digestion unit and 4 sets of dry beds. Usually, the sludge is discarded into the drying bed after the first 90 days, which is the case in normal operation before winter comes.

A type 250 biofermentation system (available from advanced corporation of fleming island, florida and installed as described in U.S. patent application publication No. 2003/0190742) was installed on site in the vicinity of the activated sludge system to be treated.

The model 250 Biofermentation apparatus was set to feed 30 gallons of 1/4 concentration of treatment ingredients per day, including microorganisms for BOD removal, under the trade designation "Bioboster for BOD removal", available from Advanced Biofertilization Services, Inc. of Fleming island, Florida. The full concentration of the treatment batch was defined as: to the bio-fermentation device was added 10 pounds of bio-nutrients (nutrients for growth of microorganisms). Thus, a treatment formula of 1/4 concentration corresponds to 1/4 or 2.5 pounds. The biological nutrients used in this process are available from advanced nutrition Services, Inc. of Fleming, Florida.

The biological fermentation process was initially scheduled to be carried out for 90 days before winter. Within 90 days of starting the treatment, the operator observed significant improvements in the treatment process, including exhibiting improved hydraulic capacity at the flood peak (sometimes above 1MGD) without incurring TSS losses in the effluent, and exhibiting better BOD removal. The observation is visually observed and described by an operator.

In the spring of the next year, surprisingly, no sludge wasting to the drying bed occurred, and therefore more attention was paid to the sludge wasting process.

After several months, the city determined that the sludge production had decreased by 75%, as determined by not using a dry bed. The city has begun purchasing a new belt press and financing $ 800,000 for replacing the dryer bed. If the city has recognized that biological fermentation can reduce net sludge waste and/or production, the city will not warrant this expense.

Importantly, gurley has noted a 65% reduction in polymer usage and a 50% increase in hydraulic capacity. Furthermore, any foaming problems are eliminated/the use of anti-foaming agents is eliminated. All of this improves the wastewater treatment process.

Example 2

For the past eight years, alum has been used in Dublin's wastewater treatment plant (WWTP) to precipitate suspended solids and associated BOD in the final effluent. The plant was a 4.0MGD trickling filter plant and had two moving bridge sand filters (sand filters) at the end that produced water that was recycled. The WWTP has three allowable cases:

(B1)4MGD，30BOD，30TSS

(B2)4MGD，25BOD，15TSS

(B3)6MGD，25BOD，30TSS

the biofermentation system described herein is provided in the WWTP of dublin city in order to increase BOD removal, reduce the use of alum in secondary clarifiers for clarification, and develop healthier biological methods to achieve the full potential of the process.

Specifically, a type 250 biofermentation system (available from advanced corporation Services, of fleming island, florida, and installed as described in U.S. patent application publication No. 2003/0190742) was installed in situ near the osmotic filtration system. The model 250 Biofermentation apparatus was set to feed 60 gallons of 1/4 concentration of treatment ingredient per day using a specific culture developed for sludge reduction under the name "Bioboster for sludge reduction" available from Advanced biofeedation Services, Inc. of Fleming island, Florida.

The treatment was run for 45 days.

After 45 days of using the biofermentation process, the city can no longer use alum, thereby saving the city about $ 100,000.

Furthermore, without the use of alum, algae thrive on the rocks of the trickling filter, the effluent BOD decreases, and TSS reaches a removal rate of 85%. It was also noted that the amount of biological sludge was significantly reduced, so that the press was switched from an amount of 2 containers per day (roll off of 20 yards each) operating 5 days per week to an amount of 1 container per day (roll off of 20 yards) operating once or twice per week.

The biological fermentation system is then permanently installed.

The significant effect is that the press is operated every two weeks after 6 months of operation. This means that: the sludge treatment cost is reduced by 70 +%. Digester sludge (including primary and secondary sludge) is also improved. Specifically, the digester sludge changed from 11/2% solids to 3% solids, and the digester produced a cleaner supernatant.

Example 3 (prophetic)

A method for improving the digestion of anaerobic sludge.

From the unexpected results of dublin, another application was recognized to be: improving the possibility of anaerobic sludge digestion.

For anaerobic digester sludge treatment, a Biofermentation device (available from Advanced biofeedation Services, fremingming, florida) was installed on site at the digester to add treatment ingredients directly to the digester. The feed rate may vary depending on the capacity of the digestion unit. However, for digestion units less than 1MGV, the feed rate is typically 10-60 gallons of 1/4 to 1/2 concentrations of furnish per day.

To obtain a faster metabolic rate, the feed rate can be doubled or quadrupled as needed to achieve the desired results.

The cost benefit to the consumer depends on improving the supernatant quality and solids consistency of the digestion unit (which contributes to the dewatering performance and results in a cost reduction of the chemicals/polymers used for dewatering). Furthermore, the running cost is due to less manpower and lower disposal frequency. In addition, the efficiency of anaerobic digestion units with limited digestion capacity is improved, thereby avoiding or minimizing capital expenditure requirements.

Example 4 (prophetic)

A method for improving sludge digestion in a homogenization tank.

From the unexpected results of gray city, another application was recognized to be: improving the possibility of sludge digestion in the homogenization basin, which is commonly used in many small towns before treatment with the plant. In addition, the use of expensive pre-treatment and/or primary clarifier tanks can be avoided.

For homogenization tank sludge treatment, a biological fermentation unit (available from advanced flocculation Services, of fleming island, florida) was installed on site at the homogenization tank to add treatment ingredients directly to the homogenization tank at the wastewater plant inlet.

The feed rate may vary depending on the volume of the homogenization tank or input stream. However, for feed streams having a volume less than 1-3MGV, the feed rate is typically 10-60 gallons of 1/4 to 1/2 concentrations of ingredient per day. Larger plants are scaled up. To obtain a faster metabolic rate, the feed rate can be doubled or quadrupled as needed to achieve the desired results.

The cost benefit to the consumer depends on improving the BOD removal rate when flowing through the homogenization tank, as well as reducing the solids accumulation to avoid or postpone the need for solids removal. Removing the solids is very expensive because it requires the cost of dewatering equipment, chemicals/polymers for dewatering, manpower, transportation and disposal costs. In addition, the treatment may improve the efficiency of capacity-limited homogenization, thereby avoiding or minimizing capital expenditure.

Example 5 (prophetic)

A method for reducing primary sludge in a primary clarifier prior to an anaerobic digestion unit.

From the unexpected results of dublin, another application was recognized to be: the potential for primary sludge in the primary clarifier prior to the anaerobic digestion unit is reduced, and primary sludge disposal is extremely expensive.

For the treatment of primary clarifier sludge, a Biofermentation device (available from Advanced biofeedation Services, fremingming, florida) was installed on site to add treatment ingredients directly to the primary clarifier sludge at the entrance of the wastewater plant.

The feed rate may vary depending on the volume of wastewater treatment plant treatment. However, for wastewater treatment plants that handle volumes less than 1-3MGV, the feed rate is typically 10-60 gallons of 1/4 to 1/2 concentrations of furnish per day. Larger plants are scaled up. To obtain a faster metabolic rate, the feed rate can be doubled or quadrupled as needed to achieve the desired results.

The cost benefit to the consumer depends on the cost of sludge treatment such as dewatering equipment, chemicals/polymers for dewatering, manpower, transportation and disposal costs to reduce the primary sludge. Furthermore, a second advantage resides in improving the efficiency of a limited capacity sludge treatment process, thereby avoiding or minimizing capital expenditure.

All patents, patent applications, provisional applications, and literature publications mentioned or cited herein are hereby incorporated by reference in their entirety, including all figures and tables, to the extent they are not inconsistent with the explicit teachings of this specification.

While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations of the invention are possible that are within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.

Claims

1. A method of improving sludge removal and maintaining discharge quality in an activated sludge wastewater treatment process, the method comprising:

introducing an incoming wastewater stream to a treatment facility, said wastewater stream having a flow rate of at least 20,000 gallons per day;

said incoming wastewater stream containing at least 50mg/L solids and 100mg/L BOD;

removing solids and BOD from the incoming wastewater stream in the treatment facility, thereby providing a first final effluent stream;

the solids in the first final effluent stream are less than 10% of the solids in the wastewater stream and BOD is less than 10% of the BOD in the wastewater stream;

whereby pounds of sludge removed is reduced by at least about 25% without an increase in the amount of solids and BOD in the final effluent stream;

wherein the method comprises treating the wastewater stream by adding a treatment ingredient from a biological fermentation unit; and is

Wherein the treatment formulation has a 10 at the point of application³-10⁴Minimal inoculation of cfu/ml.

2. The method of claim 1 wherein pounds of sludge removed is reduced by at least about 50% without an increase in the amount of solids and BOD in the final effluent stream.

3. The method of any one of the preceding claims, wherein the removal of solids and BOD produces less than about 0.25 pounds of secondary sludge per pound of BOD removed.

4. The method of any one of the preceding claims, wherein the biological fermentation device is located on-site at a site where a wastewater treatment facility is located.

5. The method of claim 4, wherein nutrients, water and an inoculum containing microorganisms are placed in the in situ system.

6. The method of claim 5, wherein the inoculum is grown to a concentration of about 10⁸-10⁹Colony forming units per milliliter (cfu/ml).

7. The method of any one of the preceding claims, wherein the biological fermentation device comprises a main tank, a water inlet, a treatment ingredient outlet, a mixing device, and a temperature control device.

8. A method according to any one of the preceding claims, wherein at least part of the treatment ingredients comprising the microorganisms are applied directly to the contaminated wastewater such that the microorganisms are not isolated, concentrated or lyophilized between the growing step and the applying step.

9. The method of any of the preceding claims, wherein the treatment furnish is added to an anaerobic digestion unit.

10. The method of any of the preceding claims, wherein the treatment ingredients are added to an equalization tank.

11. The method of any of the preceding claims, wherein the treatment furnish is added to a primary clarification device.

12. The method of any of the preceding claims, wherein the incoming wastewater stream contains at least about 100mg/L solids and 200mg/L BOD, and the removed solids are less than about 0.25 pounds of secondary sludge per pound of BOD removed.

13. The method of any of the preceding claims, wherein the incoming wastewater stream contains at least about 100mg/L solids and 400mg/L BOD, and the removed solids are less than about 0.25 pounds of secondary sludge per pound of BOD removed.

14. The method of any of claims 1 through 12, wherein the incoming wastewater stream contains at least about 100mg/L solids and 200mg/L BOD, and the removed solids are less than about 0.125 pounds of secondary sludge per pound of BOD removed.