CN106865890A - A/O‑SBBR‑Oxidation lagoon‑Constructed wetland treatment pig farm biogas slurry system - Google Patents

Abstract

A/O‑SBBR‑Oxidation Pond‑Constructed Wetland Treatment Pig Farm Biogas Slurry System, before the Sequencing Batch Biofilm Reactor (SBBR), set up the regulating tank, anoxic tank, aerobic tank, and secondary sedimentation tank in sequence, and react in the SBBR After the device, an oxidation pond and a three-level artificial wetland composed of canna, reed, cattail, wild rice and other aquatic plants are successively established; the system has a stable treatment effect, strong resistance to impact loads, simple operation, and low operating costs. The operation mode and time parameters of the SBBR reactor are water inflow for 1h, aeration for 3.5h, anoxic for 2h, aeration for 3.5h, sedimentation for 1h, and drainage for 1h. After the pig farm biogas slurry is treated by this combination process, the effluent indicators all meet the requirements of the "Pollutant Discharge Standards for Livestock and Poultry Breeding Industry" (GB 18596‑2001).

Description

A/O-SBBR-Oxidation Pond-Constructed Wetland Treatment Pig Farm Biogas Slurry System

technical field

The invention relates to a combination treatment system of anoxic/aerobic (A/O), sequencing batch biofilm reactor (SBBR), oxidation pond and constructed wetland (CW) for pig farm biogas slurry, which belongs to the field of environmental science and engineering technology .

Background technique

In recent years, my country's livestock and poultry breeding industry has developed rapidly, forming a large-scale and intensive development trend. At the same time, a large amount of livestock and poultry manure is produced, and the environmental problems caused by it are becoming increasingly serious. The Bulletin of the First National Survey of Pollution Sources shows that the annual discharge of livestock and poultry farming is 12.6826 million tons of chemical oxygen demand, 1.0248 million tons of total nitrogen, and 160,400 tons of total phosphorus. In addition, it is estimated that in 2020, the national production of livestock and poultry manure will reach 42.22×10 ⁸ t. Poultry breeding industry pollution 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. National statistics show that the pig breeding industry accounts for 47% of the scale of the livestock and poultry breeding industry, so it is necessary to increase the treatment of pig industry wastewater. At this stage, my country's large-scale pig farm wastewater treatment has basically completed anaerobic treatment, that is, anaerobic treatment structures, such as biogas digesters, have been built. After anaerobic fermentation, the macromolecular organic matter in pig farm wastewater is transformed into small molecular organic acid, and the concentration of organic matter decreases. However, a large amount of biogas slurry produced after fermentation still contains a relatively high concentration of COD and a large amount of eutrophic substances such as ammonia and phosphorus. If it is not further treated, direct discharge will cause serious damage to the surrounding ecological environment.

At present, a variety of processes have been developed for the treatment of pig farm biogas slurry at home and abroad, such as iron-carbon micro-electrolysis, SBBR process, ultrafiltration (UF) and so on. However, a single treatment process is not easy to meet the standard, and there are problems such as unstable treatment effect and high operation and management costs. At this stage, there is still a lack of economical, reasonable and technologically mature processes to treat this type 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 propose an anoxic/aerobic (A/O)-sequencing batch biofilm reactor (SBBR) for pig farm biogas slurry with high nitrogen and phosphorus concentration, high organic content and poor biodegradability. )—Oxidation Pond—Constructed Wetland (CW) Comprehensive Biogas Slurry Treatment System for pig farms. After the system is processed, the effluent indicators all meet the requirements of the "Pollutant Discharge Standards for Livestock and Poultry Breeding Industry" (GB 18596-2001).

The technical solution for realizing the present invention is: using anoxic/aerobic (A/O), sequencing batch biofilm reactor (SBBR), oxidation pond, constructed wetland (CW) four-in-one comprehensive treatment of pig farm biogas slurry,

The system is composed of: before the sequencing batch biofilm reactor, a regulating pond, anoxic pond, an aerobic pond, and a secondary sedimentation pond are sequentially set up, and after the SBBR reactor, an oxidation pond is successively established and composed of canna, reed, cattail, and wild rice. A three-level artificial wetland composed of aquatic plants.

The secondary settling tank and the sequencing batch biofilm reactor are connected with the sludge drying bed, so that the sludge in the two pools is discharged into the sludge drying bed, and the sludge drying bed is connected with the anoxic tank, so that the sludge upper layer The liquid flows to the anoxic pool. The working process of the system is as follows:

(1) The pig farm biogas slurry is collected through the pipe network, and then flows into the adjustment tank after passing through the grid to trap large particles of dung and inorganic floating objects, to adjust the water quality and water volume, and reduce the impact load;

(2) After adjustment, the biogas slurry enters the anoxic pond through the lift pump, and undergoes hydrolysis and acidification reaction under the action of heterotrophic bacteria. Degradation of organic matter improves the biodegradability of wastewater, and removes part of the suspended particles under the action of biofilm adsorption and gravity sedimentation;

(3) The effluent from the anoxic pool flows into the aerobic pool by itself. Under aerobic conditions, the microorganisms degrade a large amount of organic matter through metabolism and remove most of the ammonia nitrogen through nitrification. Improve the effect of denitrification and denitrification;

(4) The effluent from the aerobic tank enters the secondary settling tank through the lifting pump, and the wastewater is clarified hydraulically to remove the activated sludge and biofilm lost in the previous process to maintain the normal operation of the subsequent process, and the sludge in the settling tank is partially refluxed to Anoxic tank and SBBR reactor to increase the concentration of activated sludge;

(5) The effluent from the secondary sedimentation tank overflows to the SBBR reactor through the overflow weir, and the biofilm attached to the filler in the reactor is used to biochemically degrade the pollutants. Air for 3.5 hours, anoxic for 2 hours, aeration for 3.5 hours, sedimentation for 1 hour, and drainage for 1 hour. After nitrification/denitrification reactions in aerobic/anoxic conditions, COD, nitrogen, phosphorus and other pollutants are further removed;

(6) The effluent from the SBBR reactor flows into the oxidation pond by itself, and the wastewater is purified by using the symbiotic system of bacteria and algae and the aquatic biological system;

(7) The effluent of the oxidation pond flows into the constructed wetland, and the constructed wetland is connected in three stages; the first stage is a vertical flow artificial wetland, where cannas are planted; the second stage is a surface flow artificial wetland, where reeds and cattails are planted; the third stage is a subsurface flow artificial wetland , planting water bamboo and foxtail algae; the waste water is subjected to advanced treatment through multiple synergies of physics, chemistry and biology of soil, medium, plants and microorganisms, and finally discharged up to the standard;

(8) The remaining sludge from the secondary settling tank and SBBR reactor is discharged into the sludge drying bed, and the dried sludge is transported outside for treatment and disposal.

The advantages of the present invention are:

By returning the mixed solution of the O pool to the A pool, the effect of denitrification and denitrification is strengthened and no additional carbon source is required; the alkalinity produced by the denitrification process and the alkalinity consumed by the nitrification reaction form a dynamic balance, and no additional alkalinity is required , saving the cost of medicine. After the A/O process, the biodegradability of wastewater is improved, which is conducive to the normal operation of the subsequent biological treatment process of the system.

The SBBR reactor has a short start-up period, strong shock load resistance, less excess sludge production, and large equipment processing capacity. The biofilm is fixed on the surface of the filler and can inhabit microorganisms with a long generation time to form a long food chain, such as nitrifying bacteria, so the denitrification effect is good. There is no need to set up a stirring device in the reactor and no sludge reflux, and the energy consumption is small and easy to maintain and manage. The reactor can realize automatic control, which is convenient for debugging and management, and obtains the best operating parameters.

The effective water depth of the oxidation pond is 1.8m, which is divided into aerobic zone, facultative oxygen zone and anaerobic zone. Microorganisms in different water depth zones can be used to form a symbiotic system of bacteria and algae to purify wastewater. The structure of the pond is simple, economical and practical, and easy to operate and manage.

It fully exerts the wastewater treatment effect of various plants with different flow patterns in the three-level constructed wetland, and can carry out deep nitrogen and phosphorus removal. In addition, large-scale constructed wetlands can improve the system's ability to resist impact loads and at the same time play a role in beautifying the environment.

During the normal operation of the wastewater treatment process, there is no need to add chemicals, and no secondary pollution will occur. The wastewater treatment process has low operating costs and simple operation and management, which is convenient for the daily management of pig farms 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 the A/O-SBBR-oxidation pond-constructed wetland system for treating pig farm biogas slurry.

detailed description

The system of the present invention consists of: before the sequencing batch biofilm reactor (SBBR), a regulating pond, anoxic pond, an aerobic pond, and a secondary sedimentation pond are successively set up; after the SBBR reactor, an oxidation pond is successively established and composed of canna, A three-level artificial wetland composed of reeds, cattails, wild rice stems and other aquatic plants.

The secondary settling tank and the sequencing batch biofilm reactor are connected with the sludge drying bed, so that the sludge in the two pools is discharged into the sludge drying bed, and the sludge drying bed is connected with the anoxic tank, so that the sludge upper layer The liquid flows to the anoxic pool.

Pig farm biogas slurry with a processing capacity of 400m ³ /d, biogas slurry water quality: CODCr 1200-1500mg/L, NH ₃ -N 500-630mg/L, TP 20-30mg/L, SS 450-800mg/L. The pig farm biogas slurry enters the adjustment pond after passing through the grille, and the water quality and water quantity are adjusted. Then the wastewater enters the anoxic section of the A/O process, where the hydrolysis and acidification of heterotrophic bacteria is used to degrade organic matter and improve the biodegradability of wastewater. The effluent from the anoxic section flows into the aerobic section, where a large amount of organic matter is degraded through microbial metabolism and most of the ammonia nitrogen is removed through nitrification under aerobic conditions. At the same time, part of the mixed liquid in the aerobic tank is controlled to flow back to the anoxic tank to improve the effect of denitrification and denitrification. The effluent of the aerobic pool is CODCr 900~1000mg/L, NH ₃ -N 390~420mg/L, TP 18~22mg/L, SS 380~400mg/L. The effluent from the aerobic tank enters the secondary sedimentation tank through the lift pump, and the wastewater is hydraulically clarified to remove the activated sludge and biofilm lost in the previous process to maintain the normal operation of the subsequent process. The effluent from the secondary sedimentation tank flows into the SBBR reaction tank, and the biofilm attached to the filler in the reactor is used to biochemically degrade the pollutants. The operation mode and time parameters of SBBR are water inflow for 1h, aeration for 3.5h, hypoxia for 2h, aeration for 3.5h, sedimentation for 1h, and drainage for 1h. COD, nitrogen, phosphorus and other pollutants are further removed after aerobic/anoxic nitrification and denitrification. SBBR effluent CODCr 250~280mg/L, NH ₃ -N 220~250mg/L, TP 4~6mg/L, SS 230~250mg/L. The effluent from SBBR flows into the oxidation pond and the third-level constructed wetland composed of canna, reed, cattail, wild rice and other aquatic plants in turn. Wastewater undergoes advanced treatment through multiple synergistic effects of soil, artificial media, plants, and microorganisms on physics, chemistry, and biochemistry. The final effluent quality is CODCr 180-210mg/L, NH ₃ -N 30-40mg/L, and TP 2-3mg /L, SS 70~90mg/L.

Claims (1)

1. A/O-SBBR-oxidation pond-constructed wetland processing pig farm biogas slurry system is characterized in that: the system consists of: before the sequencing batch biofilm reactor is the SBBR, adjusting pond, anoxic After the SBBR reactor, an oxidation pond and a three-level artificial wetland composed of aquatic plants such as canna, reed, cattail, and wild rice stem are established in sequence; The secondary settling tank and the sequencing batch biofilm reactor (SBBR) are connected to the sludge drying bed, so that the sludge from the two pools is discharged into the sludge drying bed, and the sludge drying bed is connected to the anoxic tank to make the sludge The mud supernatant flows to the anoxic tank; The working process of the system is as follows: (1) The pig farm biogas slurry is collected through the pipe network, and then flows into the adjustment tank after passing through the grid to trap large particles of dung and inorganic floating objects, to adjust the water quality and quantity, and reduce the impact load; (2) After adjustment, the biogas slurry enters the anoxic tank through the lift pump, undergoes hydrolysis and acidification reaction under the action of heterotrophic bacteria, degrades organic matter to improve the biodegradability of wastewater, and removes it under the action of biofilm adsorption and gravity settlement Some suspended particulate matter; (3) The effluent from the anoxic pool flows into the aerobic pool by itself. Under aerobic conditions, the microorganisms degrade a large amount of organic matter through metabolism and remove most of the ammonia nitrogen through nitrification. Improve the effect of denitrification and denitrification; (4) The effluent from the aerobic tank enters the secondary sedimentation tank through the lift pump, and the wastewater is sedimented and clarified to remove the activated sludge and biofilm lost in the previous process to maintain the normal operation of the subsequent process; Part of the sludge in the secondary settling tank is returned to the anoxic tank and SBBR reactor to increase the concentration of activated sludge; (5) The effluent from the secondary sedimentation tank overflows to the SBBR reactor through the overflow weir, and the biofilm attached to the filler in the reactor is used to biochemically degrade the pollutants. Air for 3.5 hours, anoxic for 2 hours, aeration for 3.5 hours, sedimentation for 1 hour, and drainage for 1 hour. After nitrification/denitrification reactions in aerobic/anoxic conditions, COD and nitrogen and phosphorus pollutants are further removed; (6) The effluent from the SBBR reactor flows into the oxidation pond by itself, and the wastewater is further purified by using the symbiotic system of bacteria and algae and the aquatic biological system; (7) The effluent of the oxidation pond flows into the constructed wetland, and the constructed wetland is connected in three stages; the first stage is a vertical flow artificial wetland, where cannas are planted; the second stage is a surface flow artificial wetland, where reeds and cattails are planted; the third stage is a subsurface flow artificial wetland , planting water bamboo and foxtail algae; the waste water is subjected to advanced treatment through multiple synergies of physics, chemistry, and biochemistry of soil, medium, plants, and microorganisms, and finally discharges up to the standard; (8) The remaining sludge from the secondary settling tank and SBBR reactor is discharged into the sludge drying bed, and the dried sludge is transported outside for treatment and disposal.