WO2008040261A1

WO2008040261A1 - Sewage treatment plant

Info

Publication number: WO2008040261A1
Application number: PCT/CZ2006/000069
Authority: WO
Inventors: Ivan Bidenko
Original assignee: Environment Commerce Cz S.R.O.
Priority date: 2006-10-04
Filing date: 2006-10-20
Publication date: 2008-04-10
Also published as: SK288077B6; BG110172A; UA92375C2; RS20080282A; CZ2006624A3; SK50912008A3; HU227688B1; RU2338697C2; BG66054B1; HUP0800567A2; RU2006137334A; CZ300996B6; RS51321B

Abstract

The sewage treatment plant includes two wall version of the vertical cylindrical activated sludge tank (1), which is characterized by the fact that the two parallel dividing walls (4) are situated in the central part of the this tank (1), which determinate the central part (5) of the sewage treatment plant for the aerobic stabilization of the activated sludge, and simultaneously, within the space between them and the outer wall (3), create two functional symmetrically arranged areas for the sewage water and treating cultures. The separate sedimentation tanks (6) of downward tapered section are situated in these two areas. A hollow cylinder (20) is vertically situated in the axis of each sedimentation tank (6). These hollow cylinders are connected by the cross intake ducting (19) to inner area of the activated sludge tank as well as to inner area of the sedimentation tank (6) so that their outer side is adjoined by the bio-filter unit (7). Perforated piping (13) of the pressure air distribution system is situated on the bottom of the activated sludge tank. The central part (5) of the sewage treatment plant tank is vertically divided into several interconnected chambers creating a selector (9) which is connect with its inlet to the outlet of the rough contamination separator (10) or to the outlet of the drum separator (11) situated outside the sewage treatment plant tank (1), and with its outlet to the round denitrification area (16) inside the tank (1) which is arranged between the both walls (2, 3) of the sewage treatment plant tank (1) into which blenders (18) are situated to ensure the movement of the water and sludge mixture throughout the whole capacity of the denitrification area (16). This denitrification area (16) is connected by means of the through holes to the part of the activated sludge tank (1) in the area of the bio-filter units (7) into which the connection to the sedimentation lank (6) I is 'issued by the cross duct (19) while the bottom area of the sedimentation tank (6) is connected to the central part (5) of the sewage treatment plant.

Description

Sewage Treatment Plant

Technology area

Subject of the invention: Arrangement of the Sewage Treatment Plant

The present state of the art

The present engineering solutions of larger sewage treatment plants include number of separated construction and technological structures and nodes, which are interconnected with ducting, pumping units and pipe fittings. The disadvantage of these solutions is increased need for the land appropriation and repeating construction operations, such as excavation work, armouring, boarding, concrete work, etc.; this all increases investment costs and prolongs construction period. From the technological point of view such an "atomization" results in imperfect respectively only partial biological treatment, which results further in increased demands for energy caused by multiple pumping, blending, and generally more complicated technological process. Bad smell, insect infestation and noisiness are accompanying effects of such solutions.

Almost each from the known treatment processes has its fundamental deficiencies. For example, so called "SBR" process - though it seemingly integrates several processes in one sewage treatment plant tank - encounters problems related to the variable water level, sludge wash out, and energy loses at low water level conditions and associated aeration. Other known processes are often implemented on the vast structure sites with many communications; these disadvantages, among the others, result in a complicated technology controlling system, including sampling.

The goal of the submitted invention is to create structurally and technologically integrated facility of the sewage treatment plant, which eliminates many of above mentioned disadvantages.

Invention principle

The subject of this invention is represented by the arrangement of the sewage treatment plant, which includes the double-walled version of the vertical activated sludge cylindrical tank. The principle of the invention lies in the fact that the two parallel dividing walls are situated in the central part of the this tank, these walls, within the space between them, determinate the central part of the sewage treatment plant for the aerobic stabilization of the activated sludge, and simultaneously, within the space between them and the outer wall, create two functional symmetrically arranged areas for sewage water and treating cultures. Separate sedimentation tanks of downward tapered section are situated in these two areas. A hollow cylinder is situated in the axis of each sedimentation tank. These hollow cylinders are connected by the intake ducting to inner area of the activated sludge tank as well as to inner area of the sedimentation tank of which outer side is adjoined by the bio-filter unit. Perforated piping of the pressure air distribution system is situated on the bottom of the activated sludge tank. The central part of the sewage treatment plant tank is divided into several interconnected vertical chambers creating a selector which is connected with its inlet to the outlet of the rough contamination separator or to the outlet of the drum separator situated outside the sewage treatment plant tank, and with its outlet to the round denitrification area inside the tank; the round denitrification area is arranged between the both walls of the sewage treatment plant tank in which blenders are situated to ensure the movement of the water and sludge mixture throughout the whole capacity of the denitrification area. This denitrification area is connected by means of the through holes to the part of the activated sludge tank in the area of the bio-filter units into which the connection to the sedimentation is issued; while the bottom area of the sedimentation tank is connected to the central part of the sewage treatment plant. The walls of the sewage treatment plant are made of the material selected from the group of materials including concrete, metal and plastic.

The advantage of this invention is the fact that the whole system of the sewage treatment plant is compact, and arranged only in one tank (only one construction). There is no need for the multiple foundation engineering. It represents convenient space utilization and increases treatment effect while reducing the sewage treatment energy demand.

The sedimentation tanks can have the 60° angle bevel conic shape. Alternatively, they can have a flat bottom with bevelled elements laid on it; the shape of these elements can be selected from the group of shapes, including pyramid, taper, frustum of pyramid or frustum of cone, where their sides are bevelled under the 60° angle. The bevelled sides (approximately 60°) of sedimentation tanks can be conveniently used to speed up the flow of the activating mixture (water and activated sludge), which is induced by the impact of micro-bubbles, coming from the bottom through the diffusers, onto the bevelled sides of the sedimentation tanks, thus the activating^" mixture is perfectly blended, and the homogenous sludge and water mixture is created.

The bottom areas of the sedimentation tanks can be connected, through the regeneration tank situated in the central part of the sewage treatment plant, to one of the selector chambers. So, the recycled and activated sludge can be led into the selector from the bottom of the sedimentation tanks. The sewage treatment plant can conveniently include even number of sedimentation tanks, at least two, usually four but their number can be as high as eight. Separately, the sedimentation tanks can be equipped in their upper area with a clear water discharge gutter which can be connected to the water final treatment unit.

The bottom area of the sedimentation tanks can also be connected to the denitrification area. The activation sludge pull-off, the sludge is free from dissolved oxygen, from the bottom of the sedimentation tanks, which is caused by the blender action within the denitrification area, increases denitrification effect. At the denitrification area bottom piping of an additional oxidation system can be placed. The process of denitrification can be slowed down if the temperature of the surrounding environment falls down. Therefore, the denitrification area can be equipped with convenient additional oxidation system which ensures conventional biological water treatment in this area (the perforated piping of the additional oxidation system is placed near to the bottom of the denitrification area). List of Figures on Drawings

Attached drawings outline an example of the sewage treatment plant arrangement according to this invention. Figures #1 and #2 show the schematic drawing of the sewage treatment plant arrangement, figure #2 also includes the sectional view of the sewage treatment plant.

Invention implementation examples

The sewage treatment plant includes a double-walled vertical cylindrical tank 1 made of concrete, plastic, or metal; it includes outer wall 2 and concentrically arranged inner wall 3 of smaller diameter. The diameter of the outer wall 2 of the tank 1 can vary in a wide range from two meters up to several dozens of meters. The width range of the space between outer wall 3 and inner wall 2 can be from one meter up to approx. five meters depending on an actual application. The heights of both walls 2_and 3 of the tank 1 are approximately same; they can be from two meters up to ten meters high. The wall thickness depends on the material the walls are made of, and it can vary from several millimeters (if steel is used) through several centimeters (if engineering plastics are used, for example from six up to fifteen centimeters for polypropylene) up to several dozens of centimeters (up to fifty centimeters for concrete). Single components of the sewage treatment plant, including sedimentation tanks 6, stabilization tank, regeneration tank 15, and other components are integrated inside the inner tank, so called activated sludge tank which is determined by the inner wall 3 and by the tank bottom. These components are described below.

Two parallel vertically situated dividing walls 4 of the same height as the inner wall 3 are built in the inner tank creating, between themselves, the central part 5 of the sewage treatment plant determined for the activated sludge aerobic stabilization. Simultaneously, they divide the inner area of the sewage treatment plant into two symmetrical halves, so that the free passage of sewage water and treating culture between both halves of the inner concentric tank was disabled. Sedimentation tanks 6 of even number (at least two, usually four but their number can be as high as eight) can be inserted symmetrically inside the concentric inner tank. They can be rested against, and also connected to, the vertical dividing walls 4. The bottom part of each of these sedimentation tanks 6 has the 60° angle bevel conic shape, and its section is tapered downward. The bottoms of sedimentation tanks can be opened, or closed. Alternatively, the sedimentation tanks 6 can have the flat bottoms with bevelled plastic or metal elements laid on it; these elements can have the shape of pyramid, taper, frustum of pyramid or frustum of cone, with their sides bevelled under the approx. 60° angle; they ensure sedimentation of the activated sludge particles. A bottomless hollow plastic cylinder 20 can be situated conveniently in the central part of each segment of the sedimentation tank 6. The passing intake ducting .19 is issued into this hollow cylinder while its opposite end is issued into the activated sludge area of the sewage treatment plant between inner side of the inner concentric wall 3 and outer sides of the sedimentation tanks 6. Airing elements, created e.g. by the perforated silicon hoses, are placed on the bottom of the inner concentric tank (activated sludge tank). The airing elements are supplied through the pressure air distribution piping 13 with pressure air from air blowers 12 (low-pressure compressors). Next to the sedimentation tanks 6 in the activated sludge tank area on the supporting construction there are integrated bio-filter units 7 under which the pressure air distribution perforated piping 13 is situated. The pressure air is led through the pressure air distribution piping, within in advance set intervals, under the bodies of the bio-filter units 7 to remove the sludge sediments from the plastic surface of the bio-filters. Thus the optimum concentration of biological culture is kept on the surface of the bio-filters as well as in the whole activated sludge tank. The central part 5 of the sewage treatment plant, in the space between two parallel dividing walls 4 of the activated sludge tank, is divided by vertical partitions coming from the bottom along the whole height of the dividing walls 4 into several chambers which can be interconnected with ducts to enable the water circulation among them. The bottom of the central part 5 is provided with the pressure air distribution system piping 13 which is terminated with airing components; these components can consist of e.g. fine perforated silicon hoses which are slide on plastic (polypropylene, polyvinylchloride, etc.) hoses with larger holes in their surface which are connected to the piping 13. Other technological components of the sewage treatment plant are described in the chapter describing the sewage treatment plan operation.

The dirty sewage water flows through the rough contamination separator IQ. which includes e.g. thrash racks where the solid particles are separated from sewage water. When the separator 10 is shut down, for example because of accident or maintenance, sewage water flows into the drum separator of contamination H which serves as a by-pass emergency separator of solid contamination. From the separator 10_sewage water flows through the selector 9 which is created by two (conveniently by three or more) side by side arranged vertical partitions 8 interconnected by the holes in their vertical walls; the chambers are placed in the central area 5 of the sewage treatment plant between dividing walls 4 of the activated sludge tank. The air distribution piping 13 along with fine-bubble diffusers 14 are situated at the bottom of these chambers. Simultaneously, the re-circulated activated sludge from the bottom of the sedimentation tank 6 is delivered through the interconnected regeneration tank 15, which is arranged in the central part of the sewage treatment plant 5 so it adjoins the selector 9, into one of these chambers. The bottom of the regeneration tank 15 is also equipped with the pressure air distribution piping 13 and fine-bubble diffusers 14. The mixture of sewage water and activated sludge flows from the selector 9 into the denitrification area 16 between inner wall 3 and outer wall 2 of the tank 1. In this denitrification area 16 in which it is lack of dissolved free oxygen, the sludge microbes start to take away chemically bound oxygen, for example in nitrates in water, thus their content in water is reduced. This process is functional at temperatures above approx. 6⁰C. The process of denitrification is reduced at lower temperatures of surrounding environment; therefore the denitrification area 16 of the sewage treatment plant 1 is equipped with an additional oxidation system which ensures conventional biological treatment in this area (the perforated piping 17 of the additional oxidation system is placed at the bottom of the denitrification area 16). The blenders 18 are also built in this denitrification area 16 of the sewage treatment plant 1, which ensure the movement of the water and sludge mixture throughout the whole capacity of the denitrification area 16 to prevent the sludge sedimentation. The geometry of an annular ring of the denitrification area 16 is very convenient comparing with conventional tanks of different ground-plans as it shows low hydraulic friction of the water and sludge flow. Thus the energy consumption needed for the tank unity capacity blending, respectively the number of blenders 18, is reduced while the perfect the mixing of the water and sludge mixture is ensured. The denitrification area is connected by means of through holes to the activated sludge area at the place of bio-filer units 7. The water and sludge mixture flows vertically through the bio-filter units, and it is oxidized and perfectly blended at the bottom of the activated sludge tank by pressure air bubbles. The shape of bevelled sides (approximately 60°) of sedimentation tanks 6 is conveniently used to speed up the flow of the activating mixture (water and activated sludge), which is induced by the impact of micro-bubbles, coming from the bottom through the diffusers 14, onto the outer bevelled sides of the sedimentation tanks 6, thus the activating mixture is perfectly blended, and the homogenous sludge and water mixture is created. This homogenous mixture, which is needed condition for the optimum process of the biological sewage water treatment, then comes through the intake ducting 19 into the vertical hollow drum 20 which is situated in the axis of the sedimentation tank 6, from where it flows downwards to the bottom of sedimentation area. Here the treated water is separated from heavier particles which create activated sludge. Clear water then overflows the dentated brim of the discharge gutter 21 (to ensure steady flow throughout the whole length of the gutter) into the collecting channel, and further into the water final treatment unit 22 which can be a part of the sewage treatment plant 1. The water final treatment unit 22_can include drum micro-strainers, sand filters 23, or their combination. The surplus sludge is pumped from the bottom of the sedimentation tanks 6 into the central part 5 of the sewage treatment plant, equipped with oxidizing diffusers 14, here the aerobic stabilization of activated sludge is performed, and it loses its bad smell, and its volume is reduced by means of autolysis. After the oxidizing process is over the stabilized activated sludge sediments, and then it is pumped by sewage pumps 24 from the bottom into the centrifuge 25, where it islhickened7 and sludge water is retuned through the separator 10 into the selector 9 at the beginning of the treating process. The dry part of the sludge is collected into containers, and taken away.

The principles of this invention are arrangements of the sewage treatment plant, especially geometry of its denitrification area 16 and sedimentation tanks 6. The advantageous stage of this treatment process is the pull-off of activated sludge, which is free of dissolved oxygen, from the bottom of sedimentation tanks 6 into the denitrification area 16; this sludge pull-off from the environment with minimum oxygen content (the bottom of sedimentation tanks 6) is caused by the blender 18 operation in the denitrification area 16. Thus the denitrification process efficiency is increased.

A combination of two bio-cultures of different physiological activities exists in a single activated sludge tank. During their rapid growth they metabolize water contamination, and degrade organic contamination. One bio-culture is fixed on walls of the bio-filter carrier while the other one is dispersed, in a form of flakes, in activated water and sludge mixture. The combination of these bio-cultures speeds up the treatment process, and increases the sludge concentration within the system.

Industry utility of the invention

The presented invention is determined for the sewage water treatment.

Claims

PATENT SPECIFICATIONS

1. The sewage treatment plant, including two wall version of the vertical cylindrical activated sludge tank (1), which is characterized by the fact that the two parallel dividing walls (4) are situated in the central part of the tank (1), which determinate the central part (5) of the sewage treatment plant for the aerobic stabilization of the activated sludge, and simultaneously, within the space between them and the outer wall (3), create two functional symmetrically arranged areas for the sewage water and treating cultures. The separate sedimentation tanks (6) of downward tapered section are situated in these two areas. A hollow cylinder (20) is vertically situated in the axis of each sedimentation tank (6). These hollow cylinders are connected by the cross intake ducting (19) to inner area of the activated sludge tank as well as to inner area of the sedimentation tank (6) of which outer side is adjoined by the bio-filter unit (7). Perforated piping (13) of the pressure air distribution system is situated on the bottom of the activated sludge tank. The central part (5) of the sewage treatment plant tank is divided into several vertical interconnected chambers creating a selector (9) which is connect with its inlet to the outlet of the rough contamination separator (10) or to the outlet of the drum separator (11) situated outside the sewage treatment plant tank (1), and with its outlet to the round denitrification area (16) inside the tank (1) which is arranged between the both walls (2, 3) of the sewage treatment plant tank (1) in which blenders (18) are situated to ensure the movement of the water and sludge mixture throughout the whole capacity of the denitrification area (16). This denitrification area (16) is connected by means of the through holes to the part of the activated sludge tank^~(1) in the area of the bio-filter units (7) into which the connection to the sedimentation tank (6) is issued by the cross duct (19) while the bottom area of the sedimentation tank (6) is connected to the central part (5) of the sewage treatment plant.

2. The sewage treatment plant according to the specification No. 1 which is characterized by the 60° angle bevel conic shape of the sedimentation tanks (6).

3. The sewage treatment plant according to the specification No. 1 which is characterized by the fact that at least one of the sedimentation tanks (6) has a flat bottom with bevelled elements laid on it; the shape of these elements can be selected from the group of shapes, including pyramid, taper, frustum of pyramid or frustum of cone, where their sides are bevelled under the 60° angle.

4. The sewage treatment plant according to the specifications No. 2 or 3 which is characterized by the fact that the bottom area of sedimentation tanks (6) is interconnected through the regeneration tank (15) situated in the sewage treatment plant central part (5) to one of the chambers of the selector (9).

5. The sewage treatment plant according to the specification No. 4 which is characterized by the fact that the bottom area of sedimentation tanks is interconnected to the denitrification area (16).

6. The sewage treatment plant according to the specification No. 1 which is characterized by the fact that the sedimentation tanks (6) are separately equipped in their upper part by the clear water discharge gutter (21).

7. The sewage treatment plant according to the specification No. 6 which is characterized by the fact that the clear water discharge gutter (21) is connected to the water final treatment unit (22).

8. The sewage treatment plant according to the specification No. 1 which is characterized by the fact that its walls are made of materials chosen from the group of materials including concrete, metal, and plastic.

9. The sewage treatment plant according to the specification No. 1 which is characterized by the fact that it includes even number of sedimentation tanks (6).

10. The sewage treatment plant according to the specification No. 1 which is characterized by the fact that the additional oxidation system piping (17) is arranged at the bottom of the denitrification area (16).