CN106830542A - UASB two-stage A/O coagulating treatments pig farm biogas slurry system - Google Patents

Abstract

A UASB-two-stage A/O-coagulation treatment pig farm biogas slurry system, which consists of: a regulating tank, a UASB reactor, a primary anoxic pool, a primary aerobic pool, a secondary anoxic pool, and a secondary The aerobic tank, intermediate sedimentation tank, coagulation tank, secondary sedimentation tank, disinfection tank, and standard discharge outlet are connected in sequence; UASB reactor, sludge thickening tank, and plate and frame filter press are connected in sequence; intermediate sedimentation tank, secondary sedimentation tank and The coagulation tank is connected with the sludge thickening tank, so that the sludge from the third tank is discharged into the sludge thickening tank. The system has remarkable nitrogen and phosphorus removal effects, stable treatment effect, strong impact load resistance, simple operation, and low operating costs. The effluent indicators of pig farm biogas slurry after the combined process are in line with the "Livestock and Poultry Breeding Pollutant Discharge Standard" (GB 18596‑2001) requirements.

Description

UASB-two-stage A/O-coagulation treatment pig farm biogas slurry system

technical field

The invention relates to an improved upflow anaerobic sludge bed reactor (UASB), a two-stage anoxic/aerobic (two-stage A/O) and coagulation comprehensive treatment pig farm biogas slurry system, and belongs to the technical field of environmental protection water treatment.

Background technique

In recent years, my country's large-scale livestock and poultry breeding industry has developed rapidly, which has caused serious environmental pollution while increasing income and improving people's living standards. Discharge pollution from livestock and poultry breeding industry has become one of the main factors of rural non-point source pollution in my country, and also the third largest pollution source after industrial wastewater and domestic sewage. Statistics show that in 2010, the chemical oxygen demand (COD) discharged by the national livestock and poultry breeding industry has reached 12.6826 million tons, of which the high-concentration wastewater produced by intensive pig farms occupies a major position. At this stage, my country's large-scale pig farm wastewater treatment has basically completed anaerobic treatment, that is, the construction of anaerobic structures such as biogas digesters has been completed. After two stages of anaerobic acidification and methanation, the high concentration of organic matter in pig farm wastewater was basically controlled, more than 70% of COD was removed and most of the pathogenic bacteria were killed. However, a large amount of biogas slurry produced after fermentation still contains a high concentration of COD and a large amount of eutrophic substances such as ammonia and phosphorus. If it is not further treated, it will cause serious damage to the surrounding ecological environment if it is discharged directly.

At present, a variety of processes have been developed for the treatment of pig farm biogas slurry at home and abroad, mainly including aerobic treatment, anaerobic treatment, natural treatment and returning to the field for fertilizer. Biogas slurry from pig farms is still organic wastewater with high ammonia nitrogen content. Direct aerobic treatment requires excessive energy consumption and high operating costs. The appropriate solution should be a combination treatment process of anaerobic first and then aerobic treatment, but at this stage there is still a lack of economical, reasonable and technically mature combined process to treat this kind of wastewater. Therefore, it is particularly important to find a combination process that has good nitrogen and phosphorus removal effects, low investment and operating costs, adapts to local conditions, simple operation and management, and can produce certain economic and environmental benefits to solve the problem of environmental pollution caused by large-scale pig farming wastewater. .

Contents of the invention

The purpose of the present invention is to address the characteristics of high concentrations of COD, nitrogen, phosphorus, suspended matter and other pollutants in pig farm biogas slurry, large fluctuations in biogas slurry water quality over time, serious imbalance in carbon-nitrogen ratio, poor biodegradability, and difficult treatment. A UASB-two-stage A/O-coagulation comprehensive treatment system for pig farm biogas slurry is proposed. After the pig farm biogas slurry is treated by this combination process, the effluent indicators all meet the "Discharge Standards for Pollutants in Livestock and Poultry Breeding Industry" (GB 18596- 2001) requirements.

The technical solution for realizing the present invention is: UASB reactor, first-level anoxic/aerobic (first-level A/O), second-level anoxic/aerobic (secondary A/O) and coagulation four-in-one comprehensive treatment Pig farm biogas slurry. The pig farm biogas slurry finally flows out from the disinfection tank through the standard discharge port, meeting the discharge standard.

The system consists of: regulating tank, UASB reactor, primary anoxic tank, primary aerobic tank, secondary anoxic tank, secondary aerobic tank, intermediate settling tank, coagulation tank, secondary settling tank, disinfection pool, standard discharge outlets are connected in sequence; UASB, sludge thickening tank, plate and frame filter press are connected in sequence; intermediate settling tank, secondary settling tank and coagulation tank are connected with sludge thickening tank, so that the sludge from the third pool is discharged into the sludge concentration pool;

The working process of the system is as follows:

(1) The pig farm biogas slurry is collected by the pipe network, and then passes through the coarse grid to remove large particles of dung, and then flows into the regulating tank to balance the water quality and water quantity;

(2) The effluent from the regulating pool is lifted by the lift pump to the UASB reactor for anaerobic treatment, and the biogas slurry undergoes secondary hydrolysis and acidification, which greatly reduces the concentration of organic matter and reduces the processing load of the subsequent process of the system;

(3) The effluent from the UASB reactor flows into the two-stage A/O biological treatment system under the action of gravity, and the two sets of A/O processes are connected in series. The aerobic section is equipped with a return pump to return part of the mixed solution to the respective anoxic section; The first-level A/O adopts the activated sludge process, shortens the sludge age and hydraulic retention time, promotes the growth of phosphorus-accumulating bacteria, and finally uses the sludge discharge method to remove phosphorus; the second-level A/O adopts the biofilm process, prolonging the Reduce the sludge age, which is conducive to the reproduction of denitrification bacteria with long generation time, and promote the denitrification effect;

(4) The effluent from the two-stage A/O pool flows into the middle sedimentation tank, and the solid-liquid separation is carried out by gravity sedimentation, so as to further remove the suspended solids and the biofilm that fell off in the previous process, so as to ensure the water quality of the effluent;

(5) The supernatant of the middle sedimentation tank overflows into the coagulation tank, and an appropriate amount of PAC, PAM, and phosphorus removal agent slaked lime is added to the coagulation tank to make the suspended solids in the wastewater form flocs, and at the same time further reduce COD and The concentration of TP;

(6) The effluent from the coagulation tank enters the secondary sedimentation tank for solid-liquid separation, and the supernatant enters the disinfection tank, where NaClO is added for disinfection to kill Escherichia coli, pathogenic bacteria and some viruses. Finally, ensure that the effluent meets the requirements and meets the discharge standards;

(7) The sludge thickening tank in the combined process mainly collects the remaining sludge from the regulating tank, UASB reactor, intermediate settling tank, coagulation tank and secondary settling tank. After the sludge is concentrated, it passes through a plate and frame filter press to reduce the moisture content of the sludge , and then the dirty cake is transported outside for treatment and disposal.

The advantages of the present invention are:

The improved UASB reactor is based on the traditional UASB reactor, and an external circulation sludge return device is added to ensure that the anaerobic sludge is not lost. At the same time, reflux is used to increase the rising speed of the liquid in the reactor, improve the efficiency of anaerobic fermentation, and shorten the hydraulic retention time (the patent number of the improved UASB utility model is 2014200062588). In addition, the reactor is equipped with a new type of mud distributor and water distributor, among which the mud distributor prevents the return sludge from directly entering the reactor, causing the local sludge concentration to be too high and destroying the activity of anaerobic granular sludge (utility model patent number 2014200034959 ), the water distributor plays the role of uniform water distribution (utility model patent number 2014200055279). UASB can remove most of the organic pollutants in the wastewater, reduce the impact load of water quality on the subsequent process, and ensure the normal operation of the subsequent biological treatment process.

The two-stage A/0 process is connected in series, and the activated sludge method is used to remove phosphorus and the biofilm method is used to remove nitrogen. According to the different proliferation characteristics of phosphorus accumulating bacteria and nitrogen-removing bacteria, by controlling the sludge age, hydraulic retention time, aerobic The operating parameters such as the reflux ratio of the mixed liquid in the first stage overcome the problems of insufficient carbon source, nitrate interference, and sludge age in the process of traditional A ² /O denitrification and phosphorus removal. It is difficult to take into account the generation time of denitrification bacteria and phosphorus accumulation bacteria and other issues, thus achieving efficient nitrogen and phosphorus removal.

The coagulant PAC, PAM and phosphorus removal agent Ca(OH) ₂ are added to the coagulation tank, which makes the coagulation sedimentation and chemical phosphorus removal form a synergistic effect and improves the pollutant removal effect.

The wastewater treatment process has low operation cost and stable treatment effect, and is suitable for large-scale pig farm wastewater treatment and technology promotion.

After the biogas slurry is treated by the combined process, the final effluent quality is better than the requirements of the "Discharge Standard of Pollutants for Livestock and Poultry Breeding Industry" (GB18596-2001).

Description of drawings

Figure 1 is a schematic diagram of UASB-two-stage A/O-coagulation treatment pig farm biogas slurry system.

detailed description

The system of the present invention consists of: regulating tank, UASB reactor, primary anoxic tank, primary aerobic tank, secondary anoxic tank, secondary aerobic tank, intermediate sedimentation tank, coagulation tank, secondary sedimentation tank , Disinfection tank, and standard discharge port are connected in sequence; UASB reactor, sludge thickening tank, and plate-and-frame filter press are connected in sequence; intermediate settling tank, secondary settling tank, and coagulation tank are connected with sludge thickening tank, so that the sludge in the third pool Discharged into the sludge thickening tank;

Pig farm biogas slurry with a treatment capacity of 100m ³ /d, biogas slurry water quality: CODCr 2850~3000mg/L, NH ₃ -N 750~850mg/L, TP 30~40mg/L, SS 950~1300mg/L. The pig farm biogas slurry enters the adjustment pond after passing through the coarse screen, and the water quality and water quantity are adjusted. Then the wastewater is lifted by the lift pump to the UASB reactor for anaerobic treatment, and the biogas slurry undergoes secondary hydrolysis and acidification to greatly reduce the concentration of organic matter. UASB reactor effluent CODCr 700-800mg/L, NH ₃ -N 1100-1200mg/L, TP 25-30mg/L, SS 300-350mg/L. Secondly, the wastewater flows into the two-stage A/O biological treatment system under the action of gravity. The two-stage A/O process is connected in series, and the mixed liquid in the aerobic section is partially returned to the anoxic section. The first-stage A/O adopts the activated sludge method, which promotes the growth of phosphorus-accumulating bacteria by shortening the sludge age and hydraulic retention time, and finally uses the sludge discharge method to remove phosphorus. The second-level A/O adopts the biofilm method, which uses the biofilm to enrich the denitrification bacteria with a long generation time to promote the denitrification effect. Two-stage A/O pool effluent CODCr 300-400mg/L, NH ₃ -N 90-110mg/L, TP 8-10mg/L, SS 400-430mg/L. Then the wastewater enters the middle sedimentation tank for solid-liquid separation to further remove suspended solids (SS) and improve the quality of the effluent. The supernatant of the middle sedimentation tank enters the coagulation reaction tank, and PAC, PAM and slaked lime are added to make the suspended solids in the wastewater form flocs, and at the same time further reduce the concentration of COD and TP. Coagulation tank effluent CODCr 180~200mg/L, NH ₃ -N 50~70mg/L, TP 3~5mg/L, SS 180~200mg/L. The effluent from the coagulation tank enters the secondary sedimentation tank for solid-liquid separation, and then the supernatant enters the disinfection tank, where NaClO is added for disinfection, so as to ensure that the effluent meets the requirements and is discharged up to the standard. Final effluent quality CODCr 150-180mg/L, NH ₃ -N 40-60mg/L, TP 2-3mg/L, SS 100-130mg/L. In the combined process, the sludge thickening tank mainly collects the remaining sludge from the UASB reactor, intermediate settling tank, coagulation tank and secondary settling tank. After the sludge is concentrated, it passes through a plate and frame filter press to reduce the moisture content of the sludge, and then the sludge cake is transported out for treatment and disposal.

Claims (1)

1. A UASB-two-stage A/O-coagulation treatment pig farm biogas slurry system is characterized in that: the system consists of: regulating tank, UASB reactor, one-level anoxic tank, one-level aerobic tank, The secondary anoxic tank, the secondary aerobic tank, the medium sedimentation tank, the coagulation tank, the secondary sedimentation tank, the disinfection tank, and the standard discharge outlet are connected in sequence; the UASB reactor, the sludge thickening tank, and the plate and frame filter press are connected in sequence; The secondary settling tank, secondary settling tank and coagulation tank are connected to the sludge thickening tank, so that the sludge from the third tank is discharged into the sludge thickening tank; The working process of the system is as follows: (1) The pig farm biogas slurry is collected by the pipe network, and then passes through the coarse grid to remove large particles of dung, and then flows into the regulating tank to balance the water quality and water quantity; (2) The effluent from the regulating pool is lifted by the lift pump to the UASB reactor for anaerobic treatment, and the biogas slurry undergoes secondary hydrolysis and acidification, which greatly reduces the concentration of organic matter and reduces the processing load of the subsequent process of the system; (3) The effluent from the UASB reactor flows into the two-stage A/O biological treatment system under the action of gravity, the two-stage A/O processes are connected in series, and a reflux pump is set in the aerobic section to return part of the mixed solution to the respective anoxic section; the first The first-level A/O adopts the activated sludge process, which shortens the sludge age and hydraulic retention time, promotes the growth of phosphorus-accumulating bacteria, and finally uses the sludge discharge method to remove phosphorus; the second-level A/O adopts the biofilm process, which prolongs the Sludge sludge age is conducive to the reproduction of denitrification bacteria with long generation time, and promotes the denitrification effect; (4) The effluent from the two-stage A/O pool flows into the middle sedimentation tank, and the solid-liquid separation is carried out by gravity sedimentation, so as to further remove the suspended solids and the biofilm that fell off in the previous process, so as to ensure the water quality of the effluent; (5) The supernatant of the middle sedimentation tank overflows into the coagulation tank, and an appropriate amount of PAC, PAM, and phosphorus removal agent slaked lime is added to the coagulation tank to make the suspended solids in the wastewater form flocs, and at the same time further reduce COD and The concentration of TP; (6) The effluent from the coagulation tank enters the secondary sedimentation tank for solid-liquid separation, and then the supernatant enters the disinfection tank, where NaClO is added for disinfection to kill Escherichia coli, pathogenic bacteria and some viruses, and finally ensure that the effluent meets the requirements and discharges; (7) In the combined process, the sludge thickening tank collects the sludge from the adjustment tank, UASB reactor, intermediate settling tank, coagulation tank and secondary settling tank. After the sludge is concentrated, it passes through a plate and frame filter press to reduce the sludge moisture content, and then Dirty cakes are transported abroad for treatment and disposal.