CN113998833A

CN113998833A - Domestic sewage treatment method

Info

Publication number: CN113998833A
Application number: CN202110969759.0A
Authority: CN
Inventors: 何高祥; 邓强强; 赵健; 曹士海; 杜璞; 赵顺; 路群山; 苏青青; 张丽娜; 孟建雄
Original assignee: Huaneng Zhejiang Energy Development Co Ltd Yuhuan Branch
Current assignee: Huaneng Zhejiang Energy Development Co Ltd Yuhuan Branch
Priority date: 2021-08-23
Filing date: 2021-08-23
Publication date: 2022-02-01

Abstract

The invention relates to the technical field of domestic sewage, in particular to a domestic sewage treatment method. The membrane material has good hydrophilicity, mechanical property, chemical property and thermal stability, long service life, high flux, low medicament consumption, low operation and maintenance cost and energy consumption, large use temperature range, easy cleaning of the ceramic membrane, strong pollution resistance and no oxidation risk. Flow making circulation is carried out through secondary backflow, the mixed liquor containing a large amount of nitric acid base internal circulation flows back, growth and propagation of bacteria such as nitrobacteria are facilitated, high-concentration microorganisms are kept in the membrane biological reaction tank, the retention time of the bacteria is prolonged, and the nitrification efficiency is improved. The membrane intercepts macromolecular refractory substances, and the backflow prolongs the retention time and improves the degradation efficiency.

Description

Domestic sewage treatment method

Technical Field

The invention relates to the technical field of domestic sewage, in particular to a domestic sewage treatment method.

Background

At present, the domestic sewage treatment technologies mainly include physical treatment technologies (such as grating, sedimentation tank and filtration), chemical treatment technologies (such as coagulation and contact oxidation), biological treatment technologies (such as biological filter and biodegradation), and combinations of the above treatment technologies. Wherein: the physical method mainly utilizes physical action to separate or recover suspended matters in the domestic sewage, can be used for pretreatment or primary treatment of the domestic sewage, can also be used for primary treatment, but is only matched with other treatment units in secondary treatment, tertiary treatment or advanced treatment; the chemical method mainly utilizes the action of chemical reaction to treat or recover dissolved matters or colloid matters in the domestic sewage, can be used independently, and can also be used for secondary treatment or tertiary treatment; the biological method takes the pollutants contained in the sewage as a nutrient source, utilizes the physiological metabolism of microorganisms to degrade the organic pollutants and finally converts the organic pollutants into N₂、CO₂And inorganic salts, which are generally used for secondary or tertiary treatment(denitrification and dephosphorization).

The technology with the core of the A/O biological contact oxidation and MBR membrane treatment process is mature, and the microbial compound bacteria are added to improve the biochemical efficiency and greatly reduce the sludge amount. The core process route is shown in fig. 2. The A/O treatment process has the problems of short residence reaction time, loss of activated sludge, short residence time (sludge age) of microorganisms in a reactor, incapability of forming ultrahigh-concentration activated sludge concentration in a biochemical pond, incomplete sludge decomposition and the like; the traditional organic membrane has the problems of high requirement on water inflow, easy blockage, no pollution resistance, easy aging, high replacement cost and the like.

Disclosure of Invention

The invention aims to provide a domestic sewage treatment method, which realizes harmless treatment and recycling of domestic sewage, and has simpler operation and maintenance and better water quality of produced water.

The technical scheme for realizing the purpose is as follows:

a domestic sewage treatment method comprises the following steps:

s1, the domestic sewage enters a collecting tank and is primarily filtered through a grid;

s2, the sewage after primary filtration enters a regulating tank for homogenization pretreatment;

s3, the sewage after pretreatment in the adjusting tank enters an anaerobic tank, and is filtered by an MBR membrane all-in-one machine in the anaerobic tank;

s4, overflowing the filtered sewage in the anaerobic tank into an anoxic tank, and carrying out denitrification and hydrolysis reaction on the sewage;

s5, overflowing the sewage after the reaction in the anoxic tank into the aerobic tank, carrying out nitration reaction on the activated sludge, and refluxing a part of sewage into the anoxic tank;

s6, making the sewage after the reaction in the aerobic tank flow into the upper part of the membrane biological reaction tank, continuing the biochemical reaction in the membrane chamber tank, and finally filtering the sludge and bacteria through the flat ceramic membrane and producing water;

s7, returning one part of the sludge to the anaerobic tank in the step S6, and conveying the other part of the sludge to the sludge concentration tank; the water is discharged through the water production pipe.

Further, the bottom of the adjusting tank is provided with a first pump body, and sewage at the bottom of the adjusting tank is lifted to an anaerobic tank through the first pump body.

Furthermore, a second pump body is arranged at the bottom of the aerobic tank, and sludge at the bottom of the aerobic tank is lifted to the membrane biological reaction tank through the second pump body.

Further, the membrane biological reaction tank is connected with an acid washing tank and an alkali washing tank through a dosing pipeline; the membrane biological reaction tank is connected with the backwashing water tank through a backwashing pipeline.

Further, the membrane biological reaction tank is filled with a flat ceramic membrane.

Further, a sludge pump is arranged at the bottom of the membrane biological reaction tank, one part of sludge at the bottom of the membrane biological reaction tank is returned to the anaerobic tank by the sludge pump, and the other part of sludge is conveyed to the sludge concentration tank.

Further, the bottom of the reuse tank is connected to the inlet of the anaerobic tank through a reuse water pipe.

Furthermore, a sewage pump is arranged at the bottom of the adjusting tank, and the adjusting tank is connected with a reuse water tank through the sewage pump.

The device further comprises an air blower, wherein the air blower is respectively connected with the anoxic tank, the aerobic tank and the membrane biological reaction tank through air pipes; the bottom of the aerobic tank is provided with an aeration disc, and the air pipe is connected with the aeration disc.

The invention has the beneficial effects that:

the invention provides a domestic sewage treatment method, which is characterized in that a flat ceramic membrane ultrafiltration membrane is introduced for sludge-water separation, a flat ceramic membrane is filled in a membrane biological reaction tank to achieve the integration of aeration and oxygenation and filtration, strong aeration is performed to oxygenate sewage in the membrane biological reaction tank, and meanwhile, the shearing force of air bubbles and the impact force of the aeration membrane provide continuous kinetic energy for removing sediments on the surface of the membrane. The ceramic membrane replaces an organic fiber membrane, has high filling density and is easy to construct; the membrane material has good hydrophilicity, mechanical property, chemical property and thermal stability, long service life, high flux, low medicament consumption, low operation and maintenance cost and energy consumption, large use temperature range (5-60 ℃), easy cleaning of the ceramic membrane, strong pollution resistance and no oxidation risk. Flow making circulation is carried out through secondary reflux, and the mixed liquor containing a large amount of nitric acid base internal circulation is refluxed, so that the growth and the propagation of bacteria such as nitrobacteria are facilitated, the biochemical reactor is enabled to keep high-concentration microorganisms, the retention time of the bacteria is prolonged, and the nitrification efficiency is improved. The membrane intercepts macromolecular refractory substances, and the degradation efficiency is improved by prolonging the retention time through backflow.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.

The structures, ratios, sizes, and the like shown in the present specification are only used for matching with the contents disclosed in the specification, so as to be understood and read by those skilled in the art, and are not used to limit the conditions that the present invention can be implemented, so that the present invention has no technical significance, and any structural modifications, changes in the ratio relationship, or adjustments of the sizes, without affecting the effects and the achievable by the present invention, should still fall within the range that the technical contents disclosed in the present invention can cover.

FIG. 1 is a schematic view of a domestic sewage treatment system according to an embodiment of the present invention.

FIG. 2 is a flow chart of the A/O-MBR process in the prior art.

FIG. 3 is a domestic sewage treatment line according to an embodiment of the present invention.

In the figure, 1, a collection tank; 2. a regulating tank; 21. a first pump body; 22. a sewage pump; 3. an anaerobic tank; 4. an anoxic tank; 5. an aerobic tank; 51. a second pump body; 52. an aeration disc; 6. a membrane biological reaction tank; 61. a dosing pipeline; 62. a pickling tank; 63. an alkaline washing tank; 64. backwashing the pipeline; 65. a backwash water tank; 66. a backwash pump; 67. a sludge pump; 68. a water production pipe; 69. a water production pump; 7. a sludge concentration tank; 8. a reuse water tank; 81. recycling the water pipe; 9. a blower; 91. an air tube.

Detailed Description

To make the objects, technical solutions and advantages of the embodiments of the present invention clearer and more complete, the technical solutions in the embodiments of the present invention will be described below, obviously, the described embodiments are only a part of the embodiments of the present application, but not all embodiments, and the description is only for further explaining the features and advantages of the present invention, and not for limiting the claims of the present invention; all other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

In the description of the present application, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a particular orientation, be constructed in a particular orientation, and be operated, and thus should not be construed as limiting the present application.

The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless otherwise specified.

In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

The domestic sewage treatment method adopting the treatment system shown in figure 1 comprises the following steps:

s1, allowing the domestic sewage to enter a collecting tank 1, and primarily filtering through a grid;

s2, the sewage after primary filtration enters an adjusting tank 2 for homogenization pretreatment; the regulating tank 2 is used for collecting and regulating the water quantity and the water quality of the sewage, and the sewage is subjected to homogeneous pretreatment, so that the content of inorganic granular substances is preliminarily reduced, and the identity and the biodegradability of the sewage are improved;

s3, the sewage after pretreatment in the adjusting tank 2 enters an anaerobic tank 3, and is filtered by an MBR membrane all-in-one machine in the anaerobic tank 3; the sewage is hydrolyzed and acidified and macromolecular chain opening is completed in the process link, the protein is decomposed into amino acids, the polysaccharide is gradually decomposed, and the generated acetic acid and methane overflow;

s4, overflowing the filtered sewage in the anaerobic tank 3 into an anoxic tank 4, and carrying out denitrification and hydrolysis reaction on the sewage; mainly plays a role in removing nitrate nitrogen through denitrification, removes partial BOD at the same time, and also has a role in improving biodegradability through hydrolysis reaction;

s5, overflowing the sewage after the reaction in the anoxic tank 4 into the aerobic tank 5, carrying out nitration reaction on the activated sludge, and refluxing a part of the sewage into the anoxic tank 4; denitrification and dephosphorization and COD degradation are mainly carried out in the process link, activated sludge is fully subjected to nitration reaction in the tank, and most of COD, BOD, ammonia nitrogen and total phosphorus in the inlet water are fully removed through the self-metabolism effect;

s6, making the sewage after the reaction in the aerobic tank 5 flow into the upper part of the membrane biological reaction tank 6, continuing the biochemical reaction in the membrane chamber tank, and finally filtering the sludge and bacteria through the flat ceramic membrane and producing water;

s7, returning one part of the sludge to the anaerobic tank 3 in the step S6, and conveying the other part of the sludge to the sludge concentration tank 7; the water is discharged through a water production pipe 68, and a water production pump 69 is provided on the water production pipe 68.

In some embodiments of the present application, the impurities are intercepted by a grid.

In some embodiments of the present application, the bottom of the adjusting tank 2 is provided with a first pump body 21, and the sewage at the bottom of the adjusting tank 2 is lifted to the anaerobic tank 3 by the first pump body 21. Taking the ground as a reference, the depth of the regulating reservoir 2 is 5 meters, when the water level is 4 meters underground, the first pump body 21 is opened, and when the water level is 4.6 meters underground, the first pump body 21 is closed; a high water level alarm sensor is arranged 2.4 meters underground, and a low water level alarm sensor is arranged 4.7 meters underground.

In some embodiments of the present application, a second pump 51 is disposed at the bottom of the aerobic tank 5, and the sludge at the bottom of the aerobic tank 5 is lifted to the anoxic tank 4 by the second pump 51.

In some embodiments of the present application, the membrane bioreactor 6 is connected with a pickling tank 62 and an alkaline washing tank 63 through a dosing pipeline 61; the membrane biological reaction tank 6 is connected with a backwashing water tank 65 through a backwashing pipeline 64. A backwash pump 66 is provided on the backwash conduit 64.

In some embodiments of the present application, the membrane bioreactor tank 6 has three states: producing water, cleaning and backwashing.

Water production: when the system normally produces water, the valve of the water production pipe 68 is in an open state, the membrane biological reaction tank 6 produces water, and the water is lifted by the water production pump 69 and transported out of the system;

cleaning: the membrane biological reaction tank 6 stops water inflow, the valve of the water production pipe 68 is in a closed state, the water in the tank is drained, the valve of the dosing pipeline 61 is opened, and alkali washing and acid washing are carried out successively; a cleaning process: cycle → soak → cycle; the circulating cleaning flow direction is that water is fed into the inlet of the flat ceramic membrane and discharged from the backwashing pipe; wherein the alkali washing adopts sodium hypochlorite; citric acid is used for acid washing.

Backwashing: the membrane biological reaction tank 6 stops water inlet, the backwashing water tank 65 is conveyed to the membrane biological reaction tank 6 through the backwashing pipeline 64 by the backwashing pump, the bottom of the membrane biological reaction tank 6 is discharged through the backwashing pipe, and backwashing of top water inlet and bottom water outlet is carried out.

In some embodiments of the present application, the membrane bioreactor tank 6 is filled with a flat ceramic membrane.

In some embodiments of the present application, a sludge pump 67 is disposed at the bottom of the membrane biological reaction tank 6, and the sludge pump 67 returns a part of sludge at the bottom of the membrane biological reaction tank 6 to the anaerobic tank 3, and conveys the other part of sludge to the sludge concentration tank 7.

In some embodiments of the present application, the bottom of the reuse tank 8 is connected to the inlet of the anaerobic tank 3 through a reuse water pipe 81. The depth of the reuse water pool 8 is 5 meters by taking the ground as a reference, a high water level alarm sensor is arranged 2.4 meters underground, and a low water level alarm sensor is arranged 4.6 meters underground.

In some embodiments of the present application, a sewage pump 22 is disposed at the bottom of the adjusting tank 2, and the adjusting tank 2 is connected to the reuse tank 8 through the sewage pump 22.

In some embodiments of the present application, the system further comprises an air blower 9, wherein the air blower 9 is respectively connected with the anoxic tank 4, the aerobic tank 5 and the membrane biological reaction tank 6 through an air pipe 91; the bottom of the aerobic tank 5 is provided with an aeration disc 52, the air pipe 91 is connected with the aeration disc 52, and air is provided by the blower 9 to fully provide sufficient oxygen required by microorganism metabolism through an aeration head.

In FIG. 1, FW is sewage, W is a sewage pipe, H is a return pipe, N is a sludge pipe, F is a backwash pipe, C is a water production pipe, K is an air pipe, and Q is a clear water pipe.

As shown in fig. 3, domestic sewage in each area enters a septic tank, is primarily filtered by a grid of a collecting tank 1, enters an adjusting tank 2 for homogenization, is sequentially treated by an anaerobic tank 3, an anoxic tank 4, an aerobic tank 5 and a membrane biological reaction tank 6, and is lifted to a reuse water tank 8 through a water production pipe 68; the blower 9 performs timed aeration on the anoxic tank 4, performs aeration on the aerobic tank 5 and performs strong aeration on the membrane biological reaction tank 6 through an air pipe 91; the aerobic tank 5 returns the sludge to the anoxic tank 4 through the second pump body 51; the membrane biological reaction tank 6 returns the sludge to the anaerobic tank 3 through a sludge pump 67.

In the embodiment of the application, the dissolved oxygen in the anoxic tank 4 and the anaerobic tank 3 is controlled to be about 0.5 mg/l; the dissolved oxygen in the aerobic tank 5 is controlled to be more than 2 mg/L. And the sewage in the aerobic tank 5 keeps continuously flowing back, one part of the sewage in the membrane tank flows back, and the other part of the sewage is subjected to solid-liquid separation through a flat ceramic membrane. In the membrane biological reaction tank 6, a high-performance immersed flat ceramic membrane is adopted, and the ceramic membrane with the aperture of 0.03 micron can prevent bacteria from passing through, so that bacterial micelles and free bacteria in the tank can be completely retained in the aeration tank, thereby realizing mud-water separation, effectively removing various suspended particles, bacteria, algae, COD and organic matters, ensuring that the effluent suspended matters are close to zero and excellent effluent quality, and ensuring that all indexes of the treated sewage reach the standard comprehensively.

In the embodiment of the application, an MBR (flat ceramic membrane) ultrafiltration membrane is introduced for sludge-water separation, a flat ceramic membrane is filled in a membrane biological reaction tank to achieve the integration of aeration and oxygenation and filtration, strong aeration is performed to oxygenate sewage in the membrane biological reaction tank, and meanwhile, the shearing force and the impact force of air bubbles provide continuous kinetic energy for removing sediment on the surface of the membrane. The ceramic membrane replaces an organic fiber membrane, has high filling density and is easy to construct; the membrane material has good hydrophilicity, mechanical property, chemical property and thermal stability, long service life, high flux, low medicament consumption, low operation and maintenance cost and energy consumption, large use temperature range (5-60 ℃), easy cleaning of the ceramic membrane, strong pollution resistance and no oxidation risk.

In the examples of the present application, the internal circulation mixed liquid containing a large amount of nitrate and active bacterial flora was refluxed by a sludge reflux pump for the secondary reflux. The reflux liquid contains a large amount of nitrate-based internal circulation mixed liquid and active flora, which is beneficial to the growth and reproduction of slowly-proliferating nitrobacteria and other bacteria, so that the biochemical reactor can maintain high-concentration microorganisms. The membrane intercepts macromolecular refractory substances and active flora, and improves the degradation efficiency and increases the bacterial quantity by refluxing and prolonging the retention time. The biochemical reactor operates under the conditions of high volume load, low sludge load and longer sludge age, the sludge discharge amount is very little, and the sludge treatment cost is reduced.

Using the water treatment method of this example, the water inlet and outlet indexes were compared as shown in the following table

Item	Water inflow index	Index of water discharge
			COD(mg/L)	100～300	＜30
BOD(mg/L)	50～150	＜5
			Ammonia nitrogen (mg/L)	30～100	＜5
Suspended substance (mg/L)	100～1000	＜4

Although the invention has been described in detail above with reference to a general description and specific examples, it will be apparent to one skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims

1. A domestic sewage treatment method is characterized by comprising the following steps:

2. The domestic sewage treatment method according to claim 1, wherein: the sewage treatment device is characterized in that a first pump body is arranged at the bottom of the adjusting tank, and the sewage at the bottom of the adjusting tank is lifted to an anaerobic tank through the first pump body.

3. The domestic sewage treatment method according to claim 1, wherein: and a second pump body is arranged at the bottom of the aerobic tank, and the sludge at the bottom of the aerobic tank is lifted to the anoxic tank through the second pump body.

4. The domestic sewage treatment method according to claim 1, wherein: the membrane biological reaction tank is connected with the pickling tank and the alkaline washing tank through a dosing pipeline; the membrane biological reaction tank is connected with the backwashing water tank through a backwashing pipeline.

5. The domestic sewage treatment method according to claim 1, wherein: and a flat ceramic membrane is filled in the membrane biological reaction tank.

6. The domestic sewage treatment method according to claim 1, wherein: the bottom of the membrane biological reaction tank is provided with a sludge pump, one part of sludge at the bottom of the membrane biological reaction tank is returned to the anaerobic tank by the sludge pump, and the other part of sludge is conveyed to the sludge concentration tank.

7. The domestic sewage treatment method according to claim 1, wherein: the bottom of the reuse water tank is connected to the inlet of the anaerobic tank through a reuse water pipe.

8. The domestic sewage treatment method according to claim 1, wherein: the bottom of the adjusting tank is provided with a sewage pump, and the adjusting tank is connected with a reuse water tank through the sewage pump.

9. The domestic sewage treatment method according to claim 1, wherein: the device also comprises an air blower which is respectively connected with the anoxic tank, the aerobic tank and the membrane biological reaction tank through air pipes; the bottom of the aerobic tank is provided with an aeration disc, and the air pipe is connected with the aeration disc.