Method and device for resource utilization of domestic sewage

Abstract

A method and device for resource utilization of domestic sewage, belonging to the field of sewage treatment technology, consists of a sewage lifting unit, a sewage treatment unit, a sludge treatment unit and a carbon, nitrogen and phosphorus recovery unit. Domestic sewage enters the sewage treatment unit through the sewage lifting unit. The sewage treatment unit completes the treatment and reuse of domestic sewage, the intracellular synthesis of PHA microorganisms, and the concentration and enrichment of ammonia nitrogen and phosphate. The sludge treatment unit completes the concentration, chemical digestion and PHA separation and recovery of the residual sludge from the sewage treatment unit. The ammonia nitrogen and phosphate concentrates produced by the sewage treatment unit and the sludge lysate and sludge residue produced by the sludge treatment unit are then transported to the carbon, nitrogen and phosphorus recovery unit. The organic matter in the liquid is converted into volatile acid as a raw material for PHA synthesis, the ammonia nitrogen is converted into ammonium sulfate fertilizer, and the sludge residue is converted into organic fertilizer. While achieving sewage treatment, water resources, organic matter, and nitrogen and phosphorus elements are recycled and utilized.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a method and device for resource utilization of domestic sewage. Background Art

[0002] Traditional urban sewage treatment plants often remove organic matter and nitrogen and phosphorus elements as pollutants to solve the environmental pollution problems caused by domestic sewage. As of 2020, there were 4,326 sewage treatment plants in cities and counties in China, of which 2,618 were urban sewage treatment plants, with an annual sewage treatment capacity of 5,572,782 cubic meters. However, with economic development and social progress, the traditional operation model of urban sewage treatment plants has shown more and more disadvantages. During the operation of sewage treatment plants, a large amount of by-product - residual sludge - is produced. According to statistics, the total amount of sludge from sewage treatment plants in my country reached 76.763 million tons in 2021. The treatment and disposal of residual sludge is also an urgent problem that needs to be solved. Finally, in the sewage treatment process, organic matter and nitrogen and phosphorus pollutants are converted into carbon dioxide, nitrogen, phosphate precipitation, etc. through high energy consumption and material consumption, wasting resources that could have been used.

[0003] With continuous technological advancements, urban sewage treatment is evolving towards resource and energy utilization. Organic matter in urban sewage can be converted into natural gas or other products, such as sodium alginate, cellulose, and polyhydroxyalkanoates (PHA). Nitrogen and phosphorus can be enriched and processed to produce products such as struvite and violaceous iron ore. Sludge can be dried and incinerated to recover heat, and heavy metals in the incineration residue can be extracted to produce flocculants. Purified water can be supplied as recycled water for municipal water supply. Therefore, it is necessary to find a sustainable sewage treatment method that simultaneously achieves both wastewater treatment and resource utilization. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a method and device for resource utilization of domestic sewage, which can simultaneously achieve sewage treatment and resource utilization.

[0005] The technical solution of the present invention is:

[0006] A device for resource utilization of domestic sewage, characterized by comprising a sewage lifting unit (1), a sewage treatment unit (2), a sludge treatment unit (3) and a carbon, nitrogen and phosphorus recovery unit (4) which are interconnected;

[0007] The sewage lifting unit (1) includes a sewage storage tank (1-1), a sewage lifting pump I (1-2) is arranged in the sewage storage tank (1-1), and the sewage lifting pump I (1-2) is connected to the anaerobic section at the front of the AO biochemical tank (2-2) through a water inlet pipe (1-3);

[0008] The sewage treatment unit (2) includes an AO biochemical tank (2-2), an intermediate water tank (2-8) and an RO device (2-10); the AO biochemical tank (2-2) is divided into two sections connected at the bottom, wherein the front section is an anaerobic section, which is provided with a stirrer I (2-1), and the rear section is an aerobic section, which is provided with a microporous aerator (2-4), and the microporous aerator (2-4) is connected to a blower I (2-3) through a gas pipeline (2-15); the rear section of the AO biochemical tank (2-2) is connected to the blower I (2-3). An MBR membrane assembly (2-5) is provided in the aerobic section, and the outlet of the MBR membrane assembly (2-5) is connected to the intermediate water tank (2-8) through a water production pump (2-6) and a water production pipeline (2-18); a sludge return pump I (2-7) is provided in the aerobic section at the rear of the AO biochemical tank (2-2), and the sludge return pump I (2-7) is connected to the anaerobic section at the front of the AO biochemical tank (2-2) through a sludge return pipeline (2-16). At the same time, the AO biochemical tank (2 -2) is provided with a sludge return pump II (2-12) at the anaerobic section sludge outlet end in the front, and the sludge return pump II (2-12) is connected to the sludge thickening tank (3-1) in the sludge treatment unit (3) through the residual sludge discharge pipeline (2-17); the intermediate water tank (2-8) is connected to the inlet of the pressurized water inlet pump (2-9), and the outlet of the pressurized water inlet pump (2-9) is divided into two branches, one of which is connected to the solenoid valve III ( 2-13) is connected to the water inlet of the RO device (2-10), and the other branch is connected to the water inlet of the acid-producing fermentation tank (4-1) of the carbon, nitrogen and phosphorus recovery unit (4) through the outlet pipe (2-20) via the electromagnetic valve IV (2-14); the electromagnetic valve III (2-13) and the electromagnetic valve IV (2-14) are not opened at the same time; the concentrated liquid outlet of the RO device (2-10) is connected to the intermediate water tank (2-8) through the concentrated liquid circulation pipe (2-21).

[0009] The sludge treatment unit (3) includes a sludge thickening tank (3-1), a sludge chemical digestion tank (3-5), a dosing device (3-10), a centrifuge (3-12), a PHA collection tank (3-14), and a sludge lysis liquid collection tank (3-17); the sludge thickening tank (3-1) is connected to the water inlet of the sewage storage tank (1-1) through a concentrated liquid return pipe (3-4), and a sludge pump II (3-2) is provided in the sludge thickening tank (3-1). The sludge pump II (3-2) is connected to the sludge storage tank (1-1) through a concentrated liquid return pipe (3-4). The delivery pipeline I (3-3) is connected to the inlet of the sludge chemical digestion tank (3-5); the dosing device (3-10) is connected to the inlet of the sludge chemical digestion tank (3-5) through the dosing pipeline (3-11); the sludge chemical digestion tank (3-5) is equipped with a heating device (3-9), and the sludge chemical digestion tank (3-5) is internally provided with an agitator II (3-6) and a sludge pump III (3-7), and the outlet of the sludge pump III (3-7) is connected to the centrifuge (3-8) through the sludge delivery pipeline II (3-9). -12) inlet connection; the solid outlet of the centrifuge (3-12) is divided into two branches, one branch is connected to the inlet of the PHA collection tank (3-14) through the PHA delivery pipeline III (3-13), and the other branch is connected to the fertilizer production system (4-6) through the sludge discharge pipeline (3-15); the separated liquid outlet of the centrifuge (3-12) is connected to the sludge lysate collection tank (3-17) through the sludge lysate delivery pipeline (3-16); the sludge lysate collection tank (3-1 7) A sludge lysate lift pump (3-18) is provided inside, and the outlet of the sludge lysate lift pump (3-18) is divided into two branches, one branch is connected to the inlet of the acid-producing fermentation tank (4-1) through the centrifugal liquid delivery pipeline I (3-19) via the electromagnetic valve V (3-21), and the other branch is connected to the inlet of the centrifuge (3-12) through the centrifugal liquid delivery pipeline II (3-20) via the electromagnetic valve VI (3-22); the electromagnetic valve V (3-21) and the electromagnetic valve VI (3-22) are not opened at the same time;

[0010] The carbon, nitrogen and phosphorus recovery unit (4) comprises an acid-producing fermentation tank (4-1), a fertilizer production system (4-6), a stripping tower (4-7), an ammonia absorption device (4-16) and a hydrolyzate dosing pump (4-18); an agitator III (4-2) and a hydrolyzate lifting pump (4-3) are arranged inside the acid-producing fermentation tank (4-1); the hydrolyzate lifting pump (4-3) is connected to a water distribution device (4-8) arranged on the upper part of the stripping tower (4-7) through a hydrolyzate delivery pipeline I (4-4); the acid-producing fermentation tank (4-1) is connected to the fertilizer production system (4-6) through a fermentation sludge discharge pipeline (4-5); the stripping tower The bottom water outlet of (4-7) is connected to the water inlet of the front anaerobic section of the AO biochemical pool (2-2) via the hydrolyzate delivery pipeline II (4-19) via the hydrolyzate dosing pump (4-18); the lower side air inlet (4-12) of the stripping tower (4-7) is connected to the blower II (4-10) via the gas pipeline II (4-11); the upper air outlet (4-14) of the stripping tower (4-7) is connected to the ammonia absorption device (4-16) via the ammonia delivery pipeline (4-15); the ammonia absorption device (4-16) is connected to the fertilizer production system (4-6) via the ammonium sulfate delivery pipeline (4-17);

[0011] The acid fermentation tank (4-1) is also inoculated with a suspended filler (4-20) for growing hydrolytic acidifying bacteria. The suspended filler (4-20) is a circular columnar filler made of high-density polyethylene with a size of Φ10×10, a specific gravity of 0.96, and a specific surface area of ​​800m 2 / m 3 , porosity>85%, filler filling ratio 15-20%.

[0012] A filler (4-9) is provided above the air inlet (4-12) in the stripping tower (4-7), and a demister (4-13) is provided above the water distribution device (4-8) and at the air outlet (4-14) in the stripping tower (4-7).

[0013] The dosing device (3-10) is divided into two independent dosing tanks, which are respectively connected to the inlet of the sludge chemical digestion tank (3-5) through a dosing pipeline (3-11).

[0014] The method for resource utilization of domestic sewage using the above-mentioned device includes the following steps:

[0015] (1) Operation of sewage treatment unit: Domestic sewage is transported from sewage storage tank (1-1) through sewage lifting pump I (1-2) and water inlet pipe (1-3) into anaerobic section of AO biochemical tank (2-2). The concentration of activated sludge in AO biochemical tank (2-2) is 6000-7000 mg / L, and HRT of anaerobic section is 1-2h. Activated sludge in aerobic section of AO biochemical tank (2-2) is transported from sludge return pump I (2-7) through sludge return pipe (2-16) into anaerobic section of AO biochemical tank (2-2). Sludge return ratio is 1 00-150%, and at the same time, the hydrolyzed liquid stripped in the stripping tower (4-7) is transported to the anaerobic section of the AO biochemical tank (2-2) through the hydrolyzed liquid dosing pump (4-18) and the hydrolyzed liquid transport pipeline II (4-19). Under the action of the agitator I (2-1), the returned activated sludge is mixed with the influent and the hydrolyzed liquid, and the polyphosphate bacteria in the activated sludge absorb the organic matter in the influent and the hydrolyzed liquid to complete the release of phosphorus. At the same time, PHA is synthesized inside the activated sludge microbial cells; then the sludge mixed liquid enters the aerobic section, and the aerobic section HRT After 4-6 hours, blower I (2-3) supplies oxygen to the microporous aerator (2-4) through the gas pipeline (2-15), controlling the DO of the aerobic tank to 2-3 mg / L, and the activated sludge completes the phosphorus absorption reaction and removes some organic matter; an MBR membrane unit (2-5) is set in the aerobic section, which can adopt PVDF hollow fiber membrane or ceramic flat membrane with a membrane pore size of 0.1. The treated domestic sewage is filtered through the MBR membrane assembly (2-5) under the suction action of the water production pump (2-6) and enters the intermediate water tank (2-8) through the water production pipeline (2-18); the excess sludge is discharged from the excess sludge pump (2-12) through the excess sludge discharge pipeline (2-17) into the sludge thickening tank (3-1) every day, and the sludge age of the AO biochemical tank (2-2) is controlled to be 4-5 days.

[0016] The sewage in the intermediate water tank (2-8) enters the RO device (2-10) for filtration through the pressurized water inlet pump (2-9) and the water inlet pipe (2-19). The organic matter, ammonia nitrogen and phosphate in the sewage are intercepted and concentrated. The concentrated liquid is returned to the intermediate water tank (2-8) through the concentrated liquid circulation pipe (2-21). The water recovery rate of the RO device (2-10) is controlled at about 75%. The produced water is discharged as recycled water through the RO device (2-10) effluent discharge pipe (2-11) Reuse; the concentrated liquid in the intermediate water tank (2-8) is discharged into the acid-producing fermentation tank (4-1) through the pressurized water inlet pump (2-9) and the water outlet pipe (2-20) during the operation interval of the RO device (2-10); when the RO device (2-10) is inlet, the solenoid valve III (2-13) is opened; when the RO device (2-10) is discharged from the concentrated liquid, the solenoid valve IV (2-14) is opened; the solenoid valve III (2-13) and the solenoid valve IV (2-14) are not opened at the same time;

[0017] (2) Operation of sludge treatment unit: The residual sludge discharged from AO biochemical tank (2-2) enters sludge thickening tank (3-1) and is concentrated for 18-24 hours. The concentrated residual sludge is transported by sludge pump II (3-2) and enters sludge chemical digestion tank (3-5) through sludge transport pipeline I (3-14). The supernatant of sludge thickening tank (3-1) enters sewage storage tank (1-2) through concentrated liquid return pipeline (3-4); sodium dodecyl sulfate (SDS) solution with a mass percentage concentration of 10% and NaOH solution with a mass percentage concentration of 40% are stored in dosing device (3-10). Dosing device (3-10) adds NaOH and SDS to sludge chemical digestion tank (3-5) through dosing pipeline (3-11). The amount of NaOH added to sludge chemical digestion tank (3-5) is 0.2 mol / L, and the amount of SDS added is 10% of the residual sludge dry weight. The temperature of the sludge chemical digestion tank (3-3) is controlled by a heating device (3-9) to be 30±2°C. The remaining sludge is contacted with NaOH and SDS under the action of a stirrer II (3-6) for 1 hour. The bacterial cells of the microorganisms are ruptured under the action of the chemical reagents, and the organic matter in the cells, including proteins, polysaccharides, polyphosphates, PHA, etc., is released. The chemically treated remaining sludge is transported to the inlet of a centrifuge (3-12) through a sludge pump III (3-7) and centrifuged at a centrifugal force of 100-200 x g for 20-30 min. min, the cell residues precipitated after centrifugation are discharged into the fertilizer production system (4-6) through the sludge discharge pipeline (3-15), and are composted and fermented to produce organic fertilizer; the sludge lysate enters the sludge lysate collection tank (3-17) through the centrifuge (3-12) outlet and the sludge lysate delivery pipeline (3-16), and then the solenoid valve VI (3-22) is opened and the solenoid valve V (3-21) is closed at the same time to return the sludge lysate to the centrifuge (3-12) inlet, and is centrifuged again for 10-15 min under the condition of centrifugal force (such as 10000xg). in, the crude PHA extract precipitated after centrifugation is transported to the PHA collection bucket (3-14) for storage via the PHA transport pipeline III (3-13); the sludge lysate after re-centrifugation enters the sludge lysate collection tank (3-17) again via the centrifuge (3-12) outlet and the sludge lysate transport pipeline (3-16), the solenoid valve VI (3-22) is closed and the solenoid valve V (3-21) is opened to transport the sludge lysate from the sludge lysate lift pump (3-18) to the acid production fermentation tank (4-1) via the centrifuge transport pipeline I (3-19);

[0018] (3) Operation of carbon, nitrogen and phosphorus recovery unit: The acid-producing fermentation tank (4-1) is inoculated with a suspended filler (4-20) for growing hydrolytic acidifying bacteria. The suspended filler (4-20) is a circular columnar filler made of high-density polyethylene with a size of Φ10×10, a specific gravity of 0.96, and a specific surface area of ​​800m 2 / m3 , porosity>85%, filler filling ratio 15-20%, hydraulic retention time 1-2d, drainage ratio 50%, utilizing the inhibitory effect of NaOH and SDS on methanogenic bacteria, hydrolyzing the acidified sludge under the action of agitator III (4-2), converting the organic matter in the sludge lysate produced by the sludge chemical digestion tank (3-7) and the concentrated liquid produced by the RO device (2-10) into short-chain volatile fatty acids, and at the same time converting organic nitrogen into ammonia nitrogen, and phosphate into chemical sludge precipitation; The alkaline fermentation liquid in the acid-producing fermentation tank (4-1) enters the water distribution device (4-8) in the stripping tower (4-7) through the hydrolyzed liquid lifting pump (4-3) and the hydrolyzed liquid conveying pipeline I (4-4), and is evenly sprayed on the surface of the filler (4-9) through the water distribution device (4-8) to form a thin layer of liquid film. The blower II (4-10) blows air to the stripping tower (4-7) through the gas pipeline II (4-11). The air-water ratio is 2400-3000. The air and the liquid film are fully in contact, and the fermentation liquid Ammonia nitrogen is blown off by air, and the air containing ammonia nitrogen is defogged by a demister (4-13), and then enters an ammonia absorption device (4-16) from an air outlet (4-14) through an ammonia delivery pipeline (4-15). The ammonia absorption device is filled with dilute sulfuric acid with a mass percentage concentration of 15-20%. When the dilute sulfuric acid is saturated, a dilute ammonium sulfate solution is generated, which is sent to a fertilizer production system (4-6) through an ammonium sulfate delivery pipeline (4-17) to produce ammonium sulfate fertilizer through evaporation, crystallization, centrifugation, and drying processes; The stripped fermentation liquid is transported to the anaerobic section of the AO biochemical tank (2-2) via the hydrolyzate dosing pump (4-18) and the hydrolyzate delivery pipeline (4-19), and is further utilized by the polyphosphate bacteria in the activated sludge to synthesize PHA; the residual sludge containing phosphate chemical precipitation in the acid-producing fermentation tank (4-3) is fermented every day and enters the fertilizer production system (4-6) through the sludge discharge pipeline (4-5), and is composted and fermented to produce organic fertilizer, and the sludge age of the acid-producing fermentation tank (4-3) is controlled at 15-20 days.

[0019] The present invention couples the sewage treatment unit, the sludge treatment unit and the carbon, nitrogen and phosphorus recovery unit into one system, which has the following beneficial effects:

[0020] (1) While achieving sewage treatment and discharge standards, the organic matter in the sewage is converted into high-value-added PHA, the residual sludge produced is converted into organic fertilizer, and the nitrogen element is converted into ammonium sulfate, thus realizing the resource utilization of sewage.

[0021] (2) By using NaOH reagent, the PHA recovery from the dissolution of residual sludge cells, the accumulation of acid produced by organic matter fermentation, and the stripping of ammonia nitrogen in the fermentation liquid are achieved simultaneously, which reduces the number of reagents added during the wastewater resource recovery process and saves reagent costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1Structural schematic diagram of the present invention

[0023] In the figure, 1-sewage lifting unit; 2-sewage treatment unit; 3-sludge treatment unit; 4-carbon, nitrogen and phosphorus recovery unit; 1-1-sewage storage tank; 1-2-sewage lifting pump I; 1-3-water inlet pipeline; 2-1-mixer I; 2-2-AO biochemical tank; 2-3-blower I; 2-4-microporous aerator; 2-5-MBR membrane module; 2-6-water production pump; 2-7-sludge return pump I, 2-8-intermediate water tank, 2-9-pressure water inlet pump, 2-10-RO device; 2-11-effluent discharge pipeline; 2-12-excess sludge pump; 2 13-Solenoid valve III; 2-14-Solenoid valve IV; 2-15-Gas pipeline I; 2-16-Sludge return pipeline; 2-17-Excess sludge discharge pipeline; 2-18-Production water pipeline; 2-19-Water inlet pipeline; 2-20-Water outlet pipeline; 2-21-Concentrate circulation pipeline; 3-1-Sludge thickening tank; 3-2-Sludge pump II; 3-3-Sludge conveying pipeline I; 3-4-Concentrate return pipeline; 3-5-Sludge chemical digestion tank; 3-6-Agitator II; 3-7-Sludge pump III; 3-8-Sludge conveying pipeline II ;3-9-Heating device;3-10-Dosing device;3-11-Dosing pipeline;3-12 Centrifuge;3-13-PHA delivery pipeline;3-14-PHA collection tank;3-15-Sludge discharge pipeline;3-16-Sludge lysate delivery pipeline;3-17-Sludge lysate collection tank;3-18-Sludge lysate lift pump;3-19-Centrifuge delivery pipeline I;3-20-Centrifuge delivery pipeline II;3-21 Solenoid valve V;3-22 Solenoid valve VI;4-1-Acid production fermentation tank;4-2-Agitator III;4-3 -Hydrolyzate lifting pump; 4-4-Hydrolyzate delivery pipeline I; 4-5-Fermentation sludge discharge pipeline; 4-6-Fertilizer production system; 4-7-Blowing tower; 4-8-Water distribution device; 4-9-Padding; 4-10-Blower II; 4-11-Gas pipeline II; 4-12-Air inlet; 4-13-Mist eliminator; 4-14-Air outlet; 4-15-Ammonia delivery pipeline; 4-16-Ammonia absorption device; 4-17-Ammonium sulfate delivery pipeline; 4-18-Hydrolyzate dosing pump; 4-19 Hydrolyzate delivery pipeline II; 4-20 Suspended filler. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below with reference to the accompanying drawings and examples, but the present invention is not limited to the following examples.

[0025] Example 1

[0026] The properties of a domestic sewage are as follows: pH 6.5-7.5, COD350-450mg / L, BOD5200-300mg / L, NH4 +-N50-60mg / L, TN60-70mg / L, SS200-300mg / L, TP6-8mg / L. For domestic sewage use Figure 1 The domestic sewage treatment device shown in the figure comprises a sewage lifting unit (1), a sewage treatment unit (2), a sludge treatment unit (3) and a carbon, nitrogen and phosphorus recovery unit (4) which are interconnected.

[0027] The sewage lifting unit (1) is provided with a sewage lifting pump I (1-1), a sewage storage tank (1-2) and a water inlet pipeline (1-3).

[0028] The sewage treatment unit (2) is provided with an AO biochemical tank (2-2), an intermediate water tank (2-8) and an RO device (2-10). The front anaerobic section of the AO biochemical tank (2-2) is provided with an agitator I (2-1), a residual sludge pump (2-12), and the rear aerobic section of the AO biochemical tank (2-2) is provided with a blower I (2-3), a microporous aerator (2-4), an MBR membrane assembly (2-5), a water production pump (2-6), a sludge return pump I (2-7), a gas pipeline I (2-15), and a water production pipeline (2-18). The sludge return pump I (2-7) is provided with a sludge return pipeline (2-16), and the residual sludge pump (2-12) is provided with a residual sludge discharge pipeline (2-17). The RO device (2-10) is provided with a pressurized water inlet pump (2-9), a solenoid valve III (2-13) is provided on a water inlet pipeline (2-19) of the pressurized water inlet pump (2-9), a solenoid valve IV (2-14) is provided on a water outlet pipeline (2-20) of the pressurized water inlet pump (2-9), and the RO device (2-10) is provided with a concentrated liquid circulation pipeline (2-21) and a water outlet discharge pipeline (2-11).

[0029] The sludge treatment unit (3) is provided with a sludge thickening tank (3-1), a sludge chemical digestion tank (3-5), a centrifuge (3-12), a PHA collection tank (3-14), and a sludge lysis liquid collection tank (3-17); the sludge thickening tank (3-1) is provided with a sludge pump II (3-2), a sludge conveying pipeline I (3-3), and a concentrated liquid return pipeline (3-4); the sludge chemical digestion tank (3-5) is provided with an agitator II (3-6), a sludge pump III (3-7), a sludge conveying pipeline II (3-8), a heating device (3-9), a dosing device (3-10), a dosing device pipeline (3-11); the centrifuge (3-12) is provided with a PHA delivery pipeline III (3-13), a PHA collection bucket (3-14), a sludge discharge pipeline (3-15), and a sludge lysis liquid delivery pipeline (3-16); the sludge lysis liquid collection tank (3-17) is provided with a sludge lysis liquid lifting pump (3-18), a centrifugal liquid delivery pipeline I (3-19) and a centrifugal liquid delivery pipeline II (3-20); the centrifugal liquid delivery pipeline I (3-19) and the centrifugal liquid delivery pipeline II (3-20) are provided with a solenoid valve V (3-21) and a solenoid valve VI (3-22), respectively.

[0030] The carbon, nitrogen and phosphorus recovery unit (4) is provided with an acid-producing fermentation tank (4-1), a fertilizer production system (4-6) and a stripping tower (4-7). The acid-producing fermentation tank (4-1) is provided with an agitator III (4-2), a hydrolyzate lifting pump (4-3), a hydrolyzate delivery pipeline I (4-4), a fermentation sludge discharge pipeline (4-5), and a suspended filler (4-20); the stripping tower (4-7) is provided with a water distribution device (4-8), a filler (4-9), a blower II (4-10), a gas pipeline II (4-11), an air inlet (4-12), a demister (4-13), an air outlet (4-14), an ammonia delivery pipeline (4-15), an ammonia absorption device (4-16), an ammonium sulfate delivery pipeline (4-17), a hydrolyzate dosing pump (4-18), and a hydrolyzate delivery pipeline II (4-19).

[0031] The sewage storage tank (1-2) is connected to the water inlet of the AO biochemical tank (2-2) in the sewage treatment unit (2) and the bottom water outlet of the stripping tower (4-7) in the carbon, nitrogen and phosphorus recovery unit (4) through the water inlet pipeline (1-3) and the hydrolyzate delivery pipeline II (4-19); the anaerobic section at the front of the AO biochemical tank (2-2) is provided with a stirrer I (2-1), the aerobic section at the rear of the AO biochemical tank (2-2) is provided with a microporous aerator (2-4), the microporous aerator (2-4) is connected to the blower I (2-3) through the gas pipeline (2-15), and the aerobic section at the rear of the AO biochemical tank (2-2) is provided with a MB The R membrane assembly (2-5) and the MBR membrane assembly (2-5) are connected to the intermediate water tank (2-8) through a water production pump (2-6) and a water production pipeline (2-18); a sludge return pump I (2-7) is provided in the aerobic section at the rear of the AO biochemical tank (2-2), and is connected to the anaerobic section at the front of the AO biochemical tank (2-2) through the sludge return pump I (2-7) and the sludge return pipeline (2-16); at the same time, the sludge outlet end of the anaerobic section at the front of the AO biochemical tank (2-2) is connected to the sludge concentration tank (3-1) in the sludge treatment unit (3) through the sludge return pump I (2-7) and the residual sludge discharge pipeline (2-17). The intermediate water tank (2-8) is connected to the AO biochemical tank (2-2) through a water production pump (2-6) and a water production pipeline (2-18); the intermediate water tank (2-8) is connected to the water inlet of the RO device (2-10) through a pressurized water inlet pump (2-9) and a water inlet pipeline (2-19); the intermediate water tank (2-8) is connected to the concentrated liquid outlet of the RO device (2-10) through a concentrated liquid circulation pipeline (2-21); and the intermediate water tank (2-8) is connected to the water inlet of the acid-producing fermentation tank (4-1) of the carbon, nitrogen and phosphorus recovery unit (4) through the water outlet pipeline (2-20) of the pressurized water inlet pump (2-9). The water inlet pipe (2-19) and the water outlet pipe (2-20) of the pressurized water inlet pump (2-9) are respectively provided with a solenoid valve III (2-13) and a solenoid valve IV (2-14), and the solenoid valve III (2-13) and the solenoid valve IV (2-14) are not opened at the same time.

[0032] The sludge thickening tank (3-1) of the sludge treatment unit (3) is connected to the anaerobic section at the front of the AO biochemical tank (2-2) through the excess sludge pump I (2-12) and the excess sludge discharge pipeline (2-17). The sludge thickening tank (3-1) is connected to the water inlet of the sewage storage tank (1-2) through the concentrated liquid return pipeline (3-4). A sludge pump II (3-2) is installed in the sludge thickening tank (3-1). The sludge pump II (3-2) is connected to the inlet of the sludge chemical digestion tank (3-5) through the sludge conveying pipeline I (3-3). The dosing device (3-10) is connected to the inlet of the sludge chemical digestion tank (3-5) through the dosing pipeline (3-11). An agitator II (3-6), a sludge pump III (3-7) and a heating device (3-9) are arranged inside the sludge chemical digestion tank (3-5); the outlet of the sludge pump III (3-7) is connected to the inlet of a centrifuge (3-12) through a sludge conveying pipeline II (3-8); the solid outlet of the centrifuge (3-12) is connected to the inlet of a PHA collection bucket (3-14) through a PHA conveying pipeline III (3-13); and a sludge discharge pipeline (3-15) is also arranged at the solid outlet of the centrifuge (3-12) to connect to a fertilizer production system (4-6). The separated liquid outlet of the centrifuge (3-12) is connected to the sludge lysate collection tank (3-17) through the sludge lysate delivery pipeline (3-16); the sludge lysate collection tank (3-17) is provided with a sludge lysate lifting pump (3-18); the sludge lysate lifting pump (3-18) is connected to the inlet of the acid-producing fermentation tank (4-1) and the inlet of the centrifuge (3-12) through the centrifuge delivery pipeline I (3-19) and the centrifuge delivery pipeline II (3-20) respectively; the centrifuge delivery pipeline I (3-19) and the centrifuge delivery pipeline II (3-20) are respectively provided with a solenoid valve V (3-21) and a solenoid valve VI (3-22); the solenoid valve V (3-21) and the solenoid valve VI (3-22) are not opened at the same time.

[0033] A stirrer III (4-2) and a hydrolyzate lifting pump (4-3) are provided inside the acid-producing fermentation tank (4-1) in the carbon, nitrogen and phosphorus recovery unit (4); the acid-producing fermentation tank (4-1) is connected to the fertilizer production system (4-6) through a fermentation sludge discharge pipeline (4-5); the acid-producing fermentation tank (4-1) is connected to the water distribution device (4-8) in the stripping tower (4-7) through the hydrolyzate lifting pump (4-3) and the hydrolyzate delivery pipeline I (4-4); the blower II (4-10) is connected to the stripping tower through a gas pipeline II (4-11). The air inlet (4-12) of the stripping tower (4-7) is connected, the air outlet (4-14) of the stripping tower (4-7) is connected to the ammonia absorption device (4-16) through the ammonia delivery pipeline (4-15), the ammonia absorption device (4-16) is connected to the fertilizer production system (4-6) through the ammonium sulfate delivery pipeline (4-17), and the water outlet at the bottom of the stripping tower (4-7) is connected to the water inlet of the AO biochemical pool (2-2) in the sewage treatment unit (2) through the hydrolyzate dosing pump (4-18) and the hydrolyzate delivery pipeline II (4-19).

[0034] The above device is used to treat domestic sewage. The specific treatment process is as follows:

[0035] (1) Operation of sewage treatment unit: Domestic sewage is transported from sewage storage tank (1-2) through sewage lifting pump I (1-1) and water inlet pipe (1-3) into anaerobic section of AO biochemical tank (2-2). The concentration of activated sludge in AO biochemical tank (2-2) is 6000-7000 mg / L. The anaerobic section HRT 2h, the activated sludge in the aerobic section of the AO biochemical tank (2-2) is fed by the sludge return pump I (2-7) through the sludge return pipeline (2-16) into the anaerobic section of the AO biochemical tank (2-2), with a sludge return ratio of 150%. At the same time, the hydrolyzed liquid stripped in the stripping tower (4-7) is transported through the hydrolyzed liquid dosing pump (4-18) and the hydrolyzed liquid transport pipeline II (4-19) into the anaerobic section of the AO biochemical tank (2-2). Under the action of the agitator I (2-1), the returned activated sludge is mixed with the influent and the hydrolyzed liquid. The polyphosphate bacteria in the activated sludge absorb the organic matter in the influent and the hydrolyzed liquid to complete the release of phosphorus. At the same time, PHA is synthesized inside the activated sludge microbial cells, and PHA accounts for 10-15% of the dry weight of the sludge. Then the sludge mixed liquid enters the aerobic section. The aerobic section HRT 4h, blower I (2-3) supplies oxygen to the microporous aerator (2-4) through the gas pipeline (2-15), controls the DO of the aerobic tank to 2-3mg / L, and the activated sludge completes the phosphorus absorption reaction and removes part of the organic matter; the aerobic section is provided with an MBR membrane unit (2-5), which can adopt PVDF hollow fiber membrane or ceramic flat membrane with a membrane pore size of 0.1. The treated domestic sewage is filtered through the MBR membrane assembly (2-5) under the suction action of the water production pump (2-6) and enters the intermediate water tank (2-8) through the water production pipeline (2-18). The COD of the MBR effluent is 50-60mg / L, BOD5 20-30mg / L, and NH4+ -N 45-54mg / L, TN 55-65mg / L, SS 5-10mg / L, TP 0.6-0.8mg / L. The excess sludge is discharged daily from the excess sludge pump (2-12) through the excess sludge discharge pipeline (2-17) into the sludge thickening tank (3-1). The sludge age in the AO biochemical tank (2-2) is controlled at 4-5 days.

[0036] The sewage in the intermediate water tank (2-8) enters the RO device (2-10) for filtration through the pressurized water inlet pump (2-9) and the water inlet pipe (2-19). The organic matter, ammonia nitrogen and phosphate in the sewage are intercepted and concentrated. The concentrate is returned to the intermediate water tank (2-8) through the concentrate circulation pipe (2-21). The water recovery rate of the RO device (2-10) is controlled at about 75%, and the COD of the concentrate is 190-228 mg / L, and the NH4 + -N 177-208mg / L, TN 215-250mg / L, SS20-38mg / L, TP 2.1-2.7mg / L. The produced water is discharged through the RO device (2-10) outlet pipe (2-11) as recycled water. The RO outlet water COD10-12mg / L, NH4 + -N 3-8mg / L, TN 5-10mg / L, SS 0-2mg / L, TP 0.3-0.5mg / L. The concentrated liquid in the intermediate water tank (2-8) is discharged into the acid-producing fermentation tank (4-1) via the pressurized water inlet pump (2-9) and the outlet pipe (2-20) during the operation interval of the RO device (2-10). When the RO device (2-10) is inlet, the solenoid valve III (2-13) is opened; when the RO device (2-10) is discharged from the concentrated liquid, the solenoid valve IV (2-14) is opened; the solenoid valve III (2-13) and the solenoid valve IV (2-14) are not opened at the same time.

[0037] (2) Sludge treatment unit operation: The excess sludge discharged from the AO biochemical tank (2-2) enters the sludge thickening tank (3-1) and is concentrated for 18-24 hours. The concentrated sludge concentration reaches 10-15g / L. The concentrated sludge is transported by sludge pump II (3-2) and enters the sludge chemical digestion tank (3-5) through sludge conveying pipeline I (3-14). The supernatant from the sludge thickening tank (3-1) enters the sewage storage tank (1-2) through the concentrated liquid return pipeline (3-4). A 10% sodium dodecyl sulfate (SDS) solution and a 40% NaOH solution are stored in a dosing device (3-10). The dosing device (3-10) adds NaOH and SDS to a sludge chemical digestion tank (3-5) through a dosing line (3-11). The amount of NaOH added to the sludge chemical digestion tank (3-5) is 0.2 mol / L, and the amount of SDS added is 0.1-0.2 times the dry weight of the residual sludge. A heating device (3-9) controls the temperature of the sludge chemical digestion tank (3-3) to be 30±2°C. The residual sludge is contacted with NaOH and SDS by an agitator II (3-6) for 1 hour. The bacterial cells of the microorganisms are ruptured by the chemical reagents, and the intracellular organic matter including proteins, polysaccharides, polyphosphates, PHA, etc. is released. The COD in the sludge lysate is 2000-3000 mg / L. The chemically treated residual sludge is transported to the inlet of the centrifuge (3-12) via the sludge pump III (3-7) and centrifuged at a centrifugal force of 100-200 x g for 20-30 minutes. The cell residue precipitated after centrifugation is discharged through the sludge discharge pipeline (3-15) into the fertilizer production system (4-6) and composted to produce organic fertilizer. The sludge lysate enters the sludge lysate collection tank (3-17) through the outlet of the centrifuge (3-12) and the sludge lysate conveying pipeline (3-16), and then the solenoid valve VI (3-22) is opened and the solenoid valve V (3-21) is closed to return the sludge lysate to the inlet of the centrifuge (3-12). The sludge lysate is centrifuged again for 15 minutes under a centrifugal force of 10,000×g. The crude PHA extract precipitated after centrifugation is conveyed to the PHA collection tank (3-14) for storage through the PHA conveying pipeline III (3-13). The recovery rate of PHA in the sludge is 75-80%, and the amount of PHA recovered per cubic meter of sewage is approximately 0.025-0.028 kg. After the sludge lysate is centrifuged again, it enters the sludge lysate collection tank (3-17) again through the centrifuge (3-12) outlet and the sludge lysate delivery pipeline (3-16). The solenoid valve VI (3-22) is closed and the solenoid valve V (3-21) is opened at the same time to transport the sludge lysate from the sludge lysate lift pump (3-18) to the acid-producing fermentation tank (4-1) through the centrifuge delivery pipeline I (3-19).

[0038] (3) Operation of carbon, nitrogen and phosphorus recovery unit: The acid-producing fermentation tank (4-1) is inoculated with a suspended filler (4-20) for growing hydrolytic acidifying bacteria. The suspended filler (4-20) is a circular columnar filler made of high-density polyethylene with a size of Φ10×10, a specific gravity of 0.96, and a specific surface area of ​​800m 2 / m 3 , porosity>85%, filler filling ratio 15-20%, hydraulic retention time 1d, drainage ratio 50%, using the inhibitory effect of NaOH and SDS on methanogenic bacteria, hydrolyze the acidified sludge under the action of agitator III (4-2), convert the organic matter in the sludge lysate produced by the sludge chemical digestion tank (3-7) and the concentrated liquid produced by the RO device (2-10) into short-chain volatile fatty acids, and at the same time convert organic nitrogen into ammonia nitrogen, and phosphate into chemical sludge precipitation. The fermentation liquid COD is 206-262mg / L, NH4 + -N 174-206mg / L, TP 2.6-3.2mg / L. The alkaline fermentation liquid in the acid-producing fermentation tank (4-1) enters the water distribution device (4-8) in the stripping tower (4-7) through the hydrolyzate lifting pump (4-3) and the hydrolyzate delivery pipeline I (4-4). It is evenly sprayed on the surface of the filler (4-9) through the water distribution device (4-8) to form a thin liquid film. The blower II (4-10) blows air to the stripping tower (4-7) through the gas pipeline II (4-11). The air-water ratio is 3000. The air and the liquid film are fully in contact. The ammonia nitrogen in the fermentation liquid is blown off by the air, and the air containing ammonia nitrogen is removed. After being defogged by the demister (4-13), the gas enters the ammonia absorption device (4-16) from the air outlet (4-14) through the ammonia delivery pipeline (4-15). The ammonia absorption device is filled with 18% dilute sulfuric acid. When the dilute sulfuric acid is saturated, a dilute ammonium sulfate solution of about 25% is generated. The solution is then sent to the fertilizer production system (4-6) through the ammonium sulfate delivery pipeline (4-17). After evaporation, crystallization, centrifugation, and drying, ammonium sulfate fertilizer is produced. The yield of ammonium sulfate fertilizer per cubic meter of sewage is about 0.16-0.19 kg. The fermentation liquid after stripping has a COD of 196-240 mg / L, of which the VFA ratio is 50-60%, and the NH4 + -N 16-20mg / L, TP 1.3-1.6mg / L. The hydrolyzate is transported to the anaerobic section of the AO biochemical tank (2-2) via the hydrolyzate dosing pump (4-18) and the hydrolyzate delivery pipeline (4-19), where it is further utilized by the polyphosphate bacteria in the activated sludge to synthesize PHA. The excess sludge containing phosphate chemical precipitation in the acid fermentation tank (4-3) is fermented daily and then fed through the sludge discharge pipeline (4-5) to the fertilizer production system (4-6). Organic fertilizer is produced through composting and fermentation, and the sludge age in the acid fermentation tank (4-3) is controlled at 15-20 days.

Claims

1. A device for resource utilization of domestic sewage, characterized by: It includes a sewage lifting unit, a sewage treatment unit, a sludge treatment unit and a carbon, nitrogen and phosphorus recovery unit which are interconnected; The sewage lifting unit includes a sewage storage tank, in which a sewage lifting pump 1 is provided. The sewage lifting pump 1 is connected to the anaerobic section at the front of the AO biochemical tank through an inlet pipe; The sewage treatment unit includes an AO biochemical tank, an intermediate water tank, and an RO device; the AO biochemical tank is divided into two sections connected at the bottom, wherein the front section is an anaerobic section, equipped with a stirrer I, and the rear section is an aerobic section, equipped with a microporous aerator, and the microporous aerator is connected to a blower I through a gas pipeline; An MBR membrane module is installed in the aerobic section at the rear of the AO biochemical pool. The water outlet of the MBR membrane module is connected to the intermediate water pool through a water production pump and a water production pipeline. A sludge return pump I is provided in the aerobic section at the rear of the AO biochemical tank, and the sludge return pump I is connected to the anaerobic section at the front of the AO biochemical tank through a sludge return pipeline. At the same time, a sludge return pump II is provided at the sludge outlet of the anaerobic section at the front of the AO biochemical tank, and the sludge return pump II is connected to the sludge thickening tank in the sludge treatment unit through a residual sludge discharge pipeline; the intermediate water tank is connected to the inlet of the pressurized water inlet pump, and the outlet of the pressurized water inlet pump is divided into two branches, one of which is connected to the water inlet of the RO device through the water inlet pipeline via the solenoid valve III, and the other branch is connected to the water inlet of the acid-producing fermentation tank of the carbon, nitrogen and phosphorus recovery unit through the water outlet pipeline via the solenoid valve IV; the solenoid valve III and the solenoid valve IV are not opened at the same time; the concentrate outlet of the RO device is connected to the intermediate water tank through the concentrate circulation pipeline; The sludge treatment unit includes a sludge thickening tank, a sludge chemical digestion tank, a dosing device, a centrifuge, a PHA collection tank, and a sludge lysate collection tank. The sludge thickening tank is connected to the water inlet of the sewage storage tank via a concentrate return pipeline. A sludge pump II is installed in the sludge thickening tank, and the sludge pump II is connected to the inlet of the sludge chemical digestion tank via a sludge conveying pipeline I. The dosing device is connected to the inlet of the sludge chemical digestion tank through a dosing pipeline. The sludge chemical digestion tank is equipped with a heating device. An agitator II and a sludge pump III are installed inside the sludge chemical digestion tank. The outlet of the sludge pump III is connected to the inlet of the centrifuge through the sludge conveying pipeline II. The solid outlet of the centrifuge is divided into two branches. One branch is connected to the inlet of the PHA collection tank through the PHA conveying pipeline III, and the other branch is connected to the fertilizer production system through the sludge discharge pipeline. The separated liquid outlet of the centrifuge is connected to the sludge lysate collection tank through the sludge lysate conveying pipeline. A sludge lysate lifting pump is installed in the sludge lysate collection tank. The outlet of the sludge lysate lifting pump is divided into two branches. One branch is connected to the inlet of the acid-producing fermentation tank through the centrifuge conveying pipeline I via the solenoid valve V, and the other branch is connected to the inlet of the centrifuge through the centrifuge conveying pipeline II via the solenoid valve VI. The solenoid valve V and the solenoid valve VI are not opened at the same time. The carbon, nitrogen and phosphorus recovery unit includes an acidogenic fermentation tank, a fertilizer production system, a stripping tower, an ammonia absorption device and a hydrolyzate dosing pump; an agitator III and a hydrolyzate lifting pump are provided inside the acidogenic fermentation tank, and the hydrolyzate lifting pump is connected to a water distribution device provided at the upper part of the stripping tower through a hydrolyzate delivery pipeline I; the acidogenic fermentation tank is connected to the fertilizer production system through a fermentation sludge discharge pipeline; the water outlet at the bottom of the stripping tower is connected to the water inlet of the anaerobic section at the front of the AO biochemical tank through a hydrolyzate delivery pipeline II via a hydrolyzate dosing pump, the air inlet at the lower side of the stripping tower is connected to a blower II through a gas pipeline II, the air outlet at the top of the stripping tower is connected to the ammonia absorption device through an ammonia delivery pipeline, and the ammonia absorption device is connected to the fertilizer production system through an ammonium sulfate delivery pipeline; A filler is provided above the air inlet in the stripping tower, and a demister is provided above the water distribution device in the stripping tower and at the air outlet; The dosing device is divided into two independent dosing tanks, which are connected to the inlet of the sludge chemical digestion tank through dosing pipelines.

2. The device for recycling domestic sewage according to claim 1, characterized in that: The acid fermentation tank is also inoculated with suspended fillers for growing hydrolytic acidifying bacteria. The suspended fillers are round columnar fillers made of high-density polyethylene with a specific gravity of 0.96 and a specific surface area of ​​800m 2 / m 3 , porosity>85%, filler filling ratio 15-20%.

3. A method for resource utilization of domestic sewage using the device according to claim 1 or 2, characterized in that: The following procedures are included: (1) Operation of sewage treatment unit: Domestic sewage enters the anaerobic section of AO biochemical tank from sewage storage tank through sewage lifting pump I through water inlet pipe. The concentration of activated sludge in AO biochemical tank is 6000-7000 mg / L, and the HRT of anaerobic section is 1-2h. The activated sludge in aerobic section of AO biochemical tank enters the anaerobic section of AO biochemical tank from sludge return pump I through sludge return pipe. The sludge return ratio is 100-150%. At the same time, the hydrolyzed liquid in the stripping tower is transported to the anaerobic section of AO biochemical tank through hydrolyzed liquid dosing pump and hydrolyzed liquid transport pipe II. Under the action of agitator I, the returned activated sludge is mixed with influent and hydrolyzed liquid. Polyphosphate bacteria in activated sludge absorb organic matter in influent and hydrolyzed liquid to release phosphorus. At the same time, PHA is synthesized inside activated sludge microbial cells. Then the sludge mixed liquid enters the aerobic section. The HRT of aerobic section is 4-6h. Blower I supplies oxygen to microporous aerator through gas pipe to control DO of aerobic tank. 2-3mg / L, the activated sludge completes the phosphorus absorption reaction and removes some organic matter; the aerobic section is equipped with an MBR membrane module, using PVDF hollow fiber membrane or ceramic flat membrane. The treated domestic sewage is filtered through the MBR membrane module under the suction of the water production pump and enters the intermediate water tank through the water production pipeline; the residual sludge is discharged from the sludge return pump II through the residual sludge discharge pipeline into the sludge thickening tank every day, and the sludge age of the AO biochemical tank is controlled at 4-5 days; The wastewater in the intermediate water tank is filtered through the pressurized water inlet pump and the water inlet pipeline into the RO device. The organic matter, ammonia nitrogen and phosphate in the wastewater are intercepted and concentrated. The concentrate is returned to the intermediate water tank through the concentrate circulation pipeline. The water recovery rate of the RO device is controlled at 75%. The produced water is discharged through the RO device outlet discharge pipeline as recycled water. During the operation interval of the RO device, the concentrate in the intermediate water tank is discharged into the acid-producing fermentation tank through the pressurized water inlet pump and the water outlet pipeline. When the RO device is inlet, the solenoid valve III is opened; when the RO device is discharging the concentrate, the solenoid valve IV is opened. Solenoid valves III and IV are not opened at the same time. Operation of sludge treatment unit: the residual sludge discharged from AO biochemical pool enters sludge thickening pool and is concentrated for 18-24h. The concentrated residual sludge is transported by sludge pump II and enters sludge chemical digestion pool through sludge transport pipeline I. The supernatant of sludge thickening pool enters sewage storage pool through concentrated liquid return pipeline. The dosing device stores 10% mass percentage concentration of sodium dodecyl sulfate (SDS) solution and 40% mass percentage concentration of NaOH solution respectively. The dosing device adds NaOH and SDS to sludge chemical digestion pool through dosing pipeline. The dosage of NaOH in sludge chemical digestion pool is 0.2mol / L and the dosage of SDS is 0. The residual sludge is 0.1-0.2 times the dry weight of the residual sludge. The heating device controls the temperature of the sludge chemical digestion tank to 30±2℃. The residual sludge is contacted with NaOH and SDS under the action of agitator II for 1 hour. The microbial bacterial cells are ruptured under the action of chemical reagents, and the intracellular organic matter including protein, polysaccharide, polyphosphate, and PHA is released. The chemically treated residual sludge is transported to the inlet of the centrifuge via sludge pump III and centrifuged at a centrifugal force of 100-200xg for 20-30 minutes. The cell residue precipitated after centrifugation is discharged into the fertilizer production system through the sludge discharge pipeline and composted to produce organic fertilizer. The sludge lysate enters the sludge lysate collection tank through the centrifuge outlet and the sludge lysate delivery pipeline, and then the solenoid valve VI is opened and the solenoid valve V is closed to return the sludge lysate to the centrifuge inlet, and centrifuged again for 10-15 minutes under centrifugal force. The crude PHA extract precipitated after centrifugation is transported to the PHA collection tank for storage through the PHA delivery pipeline III; the sludge lysate after the second centrifugation enters the sludge lysate collection tank again through the centrifuge outlet and the sludge lysate delivery pipeline, and the solenoid valve VI is closed and the solenoid valve V is opened to transport the sludge lysate by the sludge lysate lift pump through the centrifuge delivery pipeline I to the acid production fermentation tank; Operation of the carbon, nitrogen and phosphorus recovery unit: The acid-producing fermentation tank is inoculated with suspended fillers that grow hydrolytic acidifying bacteria. The suspended fillers are round columnar fillers made of high-density polyethylene with a specific gravity of 0.96 and a specific surface area of ​​800m 2 / m 3 , porosity>85%, filler filling ratio 15-20%, hydraulic retention time 1-2d, drainage ratio 50%, using the inhibitory effect of NaOH and SDS on methanogenic bacteria, hydrolyze the acidified sludge under the action of agitator III to convert the organic matter in the sludge lysate produced by the sludge chemical digestion tank and the concentrated liquid produced by the RO device into short-chain volatile fatty acids, and at the same time convert organic nitrogen into ammonia nitrogen, and phosphate into chemical sludge precipitation; the alkaline fermentation liquid in the acid-producing fermentation tank enters the water distribution device in the stripping tower through the hydrolyzate lifting pump and the hydrolyzate delivery pipeline I, and is evenly sprayed on the surface of the filler through the water distribution device to form a thin layer of liquid film, and the blower II blows air to the stripping tower through the gas pipeline II, the gas-water ratio is 2400-3000, the air and the liquid film are fully in contact, and the fermentation liquid The ammonia nitrogen is blown off by air, and the air containing ammonia nitrogen is defogged by the demister and enters the ammonia absorption device from the air outlet through the ammonia delivery pipeline. The ammonia absorption device is filled with dilute sulfuric acid with a mass percentage concentration of 15-20%. When the dilute sulfuric acid is saturated, dilute ammonium sulfate solution is generated, which is sent to the fertilizer production system through the ammonium sulfate delivery pipeline to produce ammonium sulfate fertilizer through evaporation, crystallization, centrifugation and drying processes; the fermentation liquid that has been blown off is transported to the anaerobic section of the AO biochemical pool through the hydrolyzate dosing pump and the hydrolyzate delivery pipeline, and is further utilized by the polyphosphate bacteria in the activated sludge to synthesize PHA; the residual sludge containing phosphate chemical precipitation in the acid-producing fermentation tank is fermented every day and enters the fertilizer production system through the sludge discharge pipeline, and is composted and fermented to produce organic fertilizer, and the sludge age of the acid-producing fermentation pool is controlled at 15-20 days.

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