WO2002100783A1

WO2002100783A1 - The method of waste water treatment and the aero-selector for the realisation of this method

Info

Publication number: WO2002100783A1
Application number: PCT/SK2002/000011
Authority: WO
Inventors: Ján KURILEC
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-06-11
Filing date: 2002-06-10
Publication date: 2002-12-19
Anticipated expiration: 2003-12-11
Also published as: SK8072001A3

Abstract

The waste water treatment is realised in such a way that the waste water after the optional removal of coarse materials and/or the waste water from the adjoined anaerobic area (17) is recycled in the activation tank (1) through the oxic and anoxic part of the activation by the means of escaping air bubbles created after the air loading into the aeration device (8). At the same time sediments are washed away from the sedimentation tank (2). By the means of the optional creation of the water jump (10) onto the slot (7) by the appropriate velocity of the recycled water and air escaping from the aeration device (8) the activation mixture is pumped into the sludge area or the anaerobic area in the case of phosphorus removal. The cleaned waste water is discharged via the collection channel (11) into recipient. The aero-selector for waste water treatment consists of cylindrical, horizontal activation tank (1) on which the sedimentation tank (2) is connected whose bottom part opens radially into the lower part of the activation tank (1) and this opening area is adapted for the sedimentation degassing. The activation tank (1) is inside equipped with the aeration device (8) for the recycling and aeration of the activation mixture and with an upper opening (5) created along the activation tank (1) in the highest point of its wall. The slot (7) created between the inner wall of the activation tank (1) and the plate-shaped part (6) can end in the opening (5). The activation tank (1) can be equipped with a sludge carrier (9) of cylindrical shape with at least one opening.

Description

WASTEWATER TREATMENT BY ACTIVATED SLUDGE

Field of the invention

The invention concerns a method of the communal waste water treatment by the activation with partial sludge stabilisation, nitrogen and phosphorus removal, and an aero- selector for realisation of this method.

Background of the invention

The technological demands of activation methods of the waste water treatment, such as oxic and anoxic conditions at nitrogen elimination, anaerobic conditions at phosphorus elimination, the sludge disposal from the sedimentation, meeting requirements for material and volume load and requirements for the sludge age, impose high capital and operating demands on the present treatment processes. Conventional activation systems of waste water treatment need forced sludge water pumping from sedimentation and its further redistribution by recycling for the technological purification processes and the sludge scrappers are needed in larger waste water treatment plants. In the great majority of present technological processes of waste water treatment the influent into sedimentation is increased in the forced sludge recycling compared to the clarified water outflow by the recycled amount of water what has a negative influence on the sedimentation volume. Present conventional treatment systems do not have further using of the delivered activation air energy which is lost after bubbling the air through the water column.

There exist various activation methods of waste water treatment and their high financial and technological demands are the reason of an unsatisfactory state of the water protection against the pollution. The possibilities of a greater improvement of activation processes in the waste waters treatment are considered exhausted today.

The objectives of the invention are the simplification of the technological process of treatment, the decrease of capital and operating costs, and providing of higher ground and surface water protection. Description of the invention

This invention deals with a method of waste water treatment in small and medium waste water treatment plants. The waste water after an optional removal of coarse materials and/or the waste water from the associated anaerobic area is recycled through the oxic and anoxic part of activation by the help of the escaped air bubbles created after introduction of air into the aeration device in the aeration tank. Simultaneously sediments from the sedimentation tank are washed out into the activation tank and so this method does not need the sludge recycling from the sedimentation tank. The outlet water flowing in the lower part of the sedimentation tank through the degassing area creates a floes cloud. Gases and potential denitrification products can escape via degassing area into the sedimentation tank while the floes cloud has positive influence on the sedimentation efficiency. Because it is not necessary to increase the waste water influent to the sedimentation tank to balance the volume of removed recycled water, it is not necessary to increase the sedimentation tank volume.

The air escaping from the aeration device and the optimal velocity of recycled water create a water jump on the slot what allows pumping of activation mixture into sludge area or into the anaerobic area at phosphorus removal. The water jump causes an elevation of the level and recycling of the activated water by the outer recycling i.e. out of the activation tank as a result of hydrodynamic levels difference. This is the reason why the demands on the pumping - outer recycling by excluding forced sludge recycling from the sedimentation tank - are substantially lower compared to the current methods of the diluted sludge water removal from the sedimentation tank. The pumping demands are influenced only by the necessity of the maintenance of the required dry matter concentration in the activation tank and by the requirement for activated sludge loading into the anaerobic area at phosphorus removal.

In case when removal of the phosphorus from the waste water is necessary, the activating mixture is loaded into the anaerobic area. The cleaned waste water is discharged from the sedimentation tank into a recipient via the collecting channel.

According to the invention the aero-selector consists of a cylindrical, horizontal activation tank with a connected sedimentation tank. The bottom area of the sedimentation tank opens radially into the lower half of the activation tank and this inlet zone is adapted to the sedimentation degassing by a degassing area. The activation tank is equipped inside with an aeration device assigned for the aeration and recycling of the activation mixture.

The location of the aeration device influences the mutual relation between the energy demand of the aeration, the delivered air amount and the concurrence of the aeration intensity by the water jump. Therefore is it favourable when the aeration device is arranged eccentrically to the vertical axis of the activation tank in the direction of the activation mixture flow. The aeration device fulfils the function of a submerged aeration cylinder in such designed aero-selector.

The activation tank is equipped with an upper opening situated along the activation tank in the highest point of its wall. The slot created between the inner wall of the activation tank and the plate-shaped part joins the upper opening.

It was found that the correct shape of the slot together with the appropriate velocity of the recycled water can substantially increase the efficiency of the aeration by the water jump, by allowing the partial escape of the air bubbles outside of the slot. The bubbles will hit into the falling water of the water jump and so the water jump will take over an important part of the oxygen supply into activation tank.

It is favourable when the activation tank wall in the area of location of the plate- shaped part proceeds tangentially into a straight sector and when the slot width decreases in the direction of the activation mixture flow.

It was found that it is favourable when the segment of the activation tank wall is straight and then skewed towards the bottom of the sedimentation tank in the area of sedimentation tank location, and the adjoined curved wall is inclined in the direction of the horizontal axis of the activation tank and when the bevelled walls of the sedimentation tank have the inclination 1,7:1.

For keeping of the higher sludge age it is favourable to insert the cylindrical sludge carrier with at least one opening into the activation tank. The substantial part of the accumulated sludge will actively participate in the cleaning process. The inlet and outlet of the activation mixture from the sludge carrier can be variable, e.g. opened from above with the upper inlet and outlet, with occasional evacuation of the stabilised concentrated sludge, or with the lower inlet and upper outlet through a small slot with the automatic drain of excessive sludge. The design of the aero-selector allows covering the part of the activation tank in the relatively simple way to prevent its cooling during colder seasons and in colder regions.

The advantage of the invention is that there is not necessary to recycle the sludge from the sedimentation tank and to increase the inlet into the sedimentation tank by the amount of recycled water.

The further advantage is that the method of the cleaning using the aero-selector does not demand further technological equipment for performing the inner and outer recycling, because of washing out of the sediments from the associated sedimentation tank. In larger waste water treatment plants the scrapping of the sludge will be excluded.

The cylindrical carrier enables to achieve the high sludge age in the carrier and thereby in the activation tank as well, what considerably reduces the influence of outer recycling on the sludge age, and consequently has a positive influence on the cleaning process sensitivity. The use of the sludge carrier creates selective conditions for the suppression of filamentous micro-organisms growth, reduction of power demand for the air supply by recycling and aerating of the waste water volume decreased by the sludge carrier volume, and eventually for the anaerobic condition improvement in the sludge carrier needed for the phosphorus reduction.

The invented method of treatment by the aero-selector allows to reach the cleaning efficiency from 90 to 98 %.

Description of the figures on the sheets

The invention is further explained by the help of the attached figures. The cross- section of the aero-selector is shown in the fig.1 and the ground plan of the waste water treatment plant with a separate anaerobic area in the fig.2.

The fig.3 shows the cross-section of the aero-selector with the sludge carrier and the fig.4 shows the ground plan of the waste water treatment plant with aero-selector and sludge carrier. Examples of application of the invention

The aero-selector shown in fig. 1 is characterised by its cylindrical horizontal activation tank 1 with the connected sedimentation tank 2. The bottom area of the sedimentation tank opens radially to the area of the lower half part of the activation tank i and this opening zone is adapted to the sedimentation degassing. The activation tank 1 is equipped inside with an aeration device 8 designed for aeration and recycling of the activation mixture. The aeration device is arranged eccentrically to the vertical axis 4 of the activation tank i in the direction of the activation mixture flow. The activation tank I is equipped with an upper opening 5 constructed along the activation tank I in the highest point of its wall. The collection channel 1_1 is adjoined to the upper opening 5, and a slot 7 created between the inner wall of the activation tank I and the plate-shaped part 6 opens into it. The activation tank I wall in the area of the plate-shaped part 6 location constitutes a straight section 3.

The difference between the aero-selector shown in fig.3 and the aero-selector shown in fig.l is that the cylindrical sludge carrier 9 with one opening is installed into the activation tank I. The method of waste water treatment by the help of the aero-selector shown in fig.l is clear from the fig.2. The waste water 14, after the optional removal of coarse materials and after passing the anaerobic area 17, recycles through the oxic and anoxic part of activation by the issued air bubbles created after air loading into the aeration device 8. Simultaneously the sediments from the sedimentation tank 2 are washed away into the activation tank L The outlet water flowing in the lower part of the sedimentation tank 2 through the degassing area creates a floes cloud. Gases and denitrification products escape together from the degassing area 3 through the outlet opening 4 into the activation tank I. The air escaping through the slot 7_from the activation tank I creates together with the appropriate recycled water velocity the water jump 10. By the creation of the water jump 10 the level of activation mixture is increased, what induces the outer recycling 16 at which the activation mixture passes into the anaerobic area J 7 delivering activated sludge for the phosphorus reduction and into the sludge area 12_for the excessive sludge collection. Simultaneously the recycled water washes away sediments sliding along the sloping wall from the sedimentation tank 2 into the activation tank I. In the anaerobic area 17 is the activated mixture agitated by a separate mixer. The settled water 13 driven by gravitation force flows from the sludge area back to the activation tank JL The cleaned waste water J_5 is discharged via the collection channel ϋ into a recipient.

The method of the waste water treatment by the aero-selector shown in the fig. 3 and 4 is the same as the method of treatment by the aero-selector shown in the fig. 1 and 2. The only difference is that the sludge carrier 9 with an upper opening is inserted into the activation tank i and that the treatment does not have a separate anaerobic area.

The cylindrical sludge carrier 9 provides a high sludge age in the carrier as well as in the activation tank 1. This considerably reduces the influence of the outer recycling 16 on the sludge age with the final favourable effect on the cleaning process sensitivity. Using the sludge carrier 9 creates selective conditions for the suppressing the growth of filamentous micro-organisms, for the decreasing of power demand of the air supply by recycling and aerating of the water volume decreased by the volume of sludge carrier 9, and optionally for the anaerobic conditions in the sludge carrier 9 needed for the phosphorus reduction.

Industrial Applicability

The method of waste water cleaning by the aero-selector is suitable for small to medium waste water treatment plants.

Claims

1. Method of waste water cleaning characterised by that it is realised by the aero-selector, where the waste water after optional removal of coarse materials and/or the waste water from the associated anaerobic area (17) recycles in the activation tank (1) through the oxic and anoxic part of activation by means of escaping air bubbles created after air loading into aeration device (8) while washing away the sediments from the sedimentation tank (2), or by creating the water jump (10) onto the slot (7) by the means of the appropriate recycled water velocity and escaping air from the aeration device (8) the activation mixture is pumped into the sludge area or into the anaerobic area for the phosphorus removal and the cleaned waste water is in this way discharged from the sedimentation tank via the collection channel (11) into the recipient.

2. Aero-selector for the realisation according to Claim 1 characterised by that it consists of cylindrical, horizontal activation tank (1) to which the sedimentation tank (2) is connected, equipped by a channel (11) for the cleaned water discharge and which bottom part opens radially into the area of the lower part of the activation tank (1) and this zone of the opening is adapted for sedimentation degassing, while the activation tank(l) is equipped inside with the aeration device (8) for the aeration and recycling of activation mixture as ell as with an upper opening (5) created along of the activation tank (1) in the highest point of its wall.

3. Aero-selector according to Claim 2 characterised by that the slot (7) created between the inner wall of the activation tank (1) and the plate-shaped part (6) opens into the upper opening (5).

4. Aero-selector according to Claim 2 and 3 characterised by that the activation tank (1) is equipped with the aeration device (8) for the recycling and aeration of the activation mixture, which is arranged eccentrically to the vertical axis (1.4) of the activation tank in the direction of the activation mixture flow.

5. Aero-selector according to Claim 2 to 4 characterised by that it is favourable when the wall of the activation tank (1) proceeds tangentially into a straight segment (1.3) in the area of the slab-shaped part (6) location.

6. Aero-selector according to Claim 2 to 5 characterised by that it is favourable when the width of the slot (7) decreases in the direction of the activation mixture flow.

7. Aero-selector according to Claim 2 to 6 characterised by that the segment (1.2) of the activation tank (1) wall is straight in the area of the activation tank (2) location, bevelled towards the sedimentation tank (2) and the curved wall (1.1) adjoined to the segment (1.2) is inclined towards the horizontal axis (1.5) of the activation tank (1).

8. Aero-selector according to Claim 2 to 7 characterised by that the sedimentation tank (2) is created by bevelled walls (1.2, 2.1) preferably with the 1,7:1 inclination.

9. Aero-selector according to Claim 2 to 8 characterised by that it is favourable when the activation tank (1) is equipped with a sludge carrier (9) having a cylindrical shape and at least one opening.