CN105110567A - Process for advanced treatment of southern large-scale swine wastewater - Google Patents

Abstract

The invention relates to a process suitable for advanced treatment of large-scale pig raising wastewater in the south, belonging to the technical field of wastewater treatment; the process is as follows: the breeding wastewater first enters the adjustment pool I, and the pretreated wastewater is separated by a solid-liquid separator (waste residue can be used in agriculture) , the separated liquid enters the biogas digester for more than 7 days of anaerobic fermentation, the biogas liquid enters the adjustment pond II, and after 1 day of sedimentation (floating) and reoxygenation, it enters the biological filler oxidation pond, and after a residence time of 2 days, it enters the ecological oxidation pond, and the oxidation pond is set Artificial aquatic plants, after 20 days of treatment, are lifted by water pumps into the vertical flow artificial wetland. The wetland adopts PVC pipe frame type water distribution, and canna is planted on the surface. The advantage of this process lies in the high efficiency of wastewater treatment, low operating cost and simple maintenance.

Description

A process for the advanced treatment of large-scale pig raising wastewater in the south

technical field

The invention relates to a wastewater treatment process, in particular to a process suitable for advanced treatment of large-scale pig raising wastewater in the south, and belongs to the technical field of wastewater treatment.

Background technique

The intensification level of large-scale pig farms in southern my country, especially in Guangdong and Guangxi, continues to increase, and the impact of pig wastewater on the environment is also becoming more and more serious. Taking the western part of Guangdong Province as an example, in accordance with the emission reduction requirements of the Ministry of Environmental Protection, the dry manure cleaning model has been promoted nationwide to reduce emissions. However, due to the climate differences between the northern and southern regions of my country, the annual average temperature in the south is high and the humidity is high, while the temperature in the north is low and the climate is dry. However, the dry manure (litter) mode widely used in the north is difficult to achieve in the south. At present, the pig farming industry in western Guangdong basically still adopts the traditional water flushing manure farming method, coupled with the high level of intensive farming and the large amount of farming, resulting in an astonishing amount of breeding wastewater. In addition, due to the relatively high discharge standards of aquaculture wastewater in my country (COD and ammonia nitrogen discharge standards are 400mg/L and 80mg/L respectively, "Discharge Standards of Pollutants for Livestock and Poultry Breeding Industry" (GB18596-2001)), even if all breeding enterprises If the discharge can meet the standard, the impact of tail water discharge on the water quality of the receiving water body is still relatively large.

At present, there are two main modes of large-scale pig wastewater treatment in my country: comprehensive utilization mode and industrialized treatment mode. The comprehensive utilization mode can be divided into the field return mode and the natural treatment mode: the field return mode Returning feces waste water to the field as fertilizer is a traditional, cost-effective disposal method that can realize nutrient recycling, but requires a large amount of land to support the farm , There are problems such as the risk of spreading livestock and poultry diseases and zoonotic diseases, non-point source pollution and the harm of heavy metals and antibiotic deposition to the soil; the natural treatment mode is mainly simple oxidation ponds and artificial wetlands, which have large land occupation and low treatment efficiency. For low-level problems, small-scale breeding enterprises mostly adopt comprehensive utilization models. The industrialized treatment mode has become the main wastewater treatment method for large-scale farms because of its high efficiency and stable water output: N.Bernet et al. used the ASBR (anaerobic-SBR) process (2000) to treat pig wastewater and found that NO _x -N removal rate and reflux ratio It is inversely proportional to denitrification during water inflow and ammonia nitrogen stripping during aeration will increase its removal rate. The removal rates of total organic carbon and total Kjeldahl nitrogen are 81%-91% and 85%-91% respectively; the solid-liquid developed by the University of Hawaii When the separation + anaerobic + aerobic + stone filter process was used to treat pig wastewater, it was found that the aeration method had a great influence on the treatment effect (PYYangetal. 1999); the ammonia crystallization + anaerobic + aerobic + limestone treatment process (PYYangetal. HRT=30h, when the aeration/non-aeration time ratio is 1, the pig wastewater is treated. The results show that: TP, COD, and TN are 98%, 93.5%, and 95.1% respectively. Large-scale breeding enterprises generally adopt industrialized treatment mode. However, due to the high construction cost of industrialized wastewater treatment facilities and the need for professional maintenance and management, some enterprises often fail to meet the design requirements or simply idle in order to reduce costs.

Constructed wetlands—that is, using the physical, chemical, and biological triple synergies among substrates, plants, and microorganisms—purify sewage through filtration, adsorption, ion exchange, plant absorption, and microbial degradation (Wang Shihe, 2007 ). Water purification by constructing artificial wetlands began in the middle of the 20th century. The 4th International Symposium held in Vienna, Austria in September 1996 marked that the artificial wetland system officially entered the field of water pollution control as a unique new wastewater treatment technology (Brix , 1986; USEPA, 2000). Since then, the use of constructed wetlands has become more and more widespread. Among them, Europe and the United States have mostly used constructed wetlands to treat livestock and poultry breeding wastewater. The US Natural Resources Conservation Service has compiled guidelines for the treatment of breeding wastewater, suggesting that the B0D ₅ load of constructed wetlands is 73kg/hm ² . d, HRT at least 12d. In New Zealand, Japan, Australia and some African countries, constructed wetland treatment technology has also been widely used (Yang Qiong et al., 2002).

Contents of the invention

The purpose of the present invention is to provide a process suitable for the advanced treatment of large-scale pig raising wastewater in the south. The advanced wastewater treatment process has low investment, low operating cost, high treatment efficiency and high degree of automation.

For realizing the above-mentioned purpose of the invention, the technical scheme that the present invention takes is as follows:

A process for the advanced treatment of large-scale pig raising wastewater in the south, comprising the following steps:

(1) Wastewater pretreatment: Pig excrement and flushing water aquaculture wastewater are collected in the adjustment tank Ⅰ through the collection pipe network to form a feed liquid, and a solid-liquid separator is installed beside the pool, and the feed liquid is divided into solid feces residues after being treated by the separator material and separating liquid;

(2) Biogas slurry sedimentation: The separated liquid enters the biogas digester, and after more than 7 days of anaerobic fermentation, biogas and biogas slurry are formed. The slag floats and the sludge sinks, and the biogas slurry enters the biological filler oxidation tank;

(3) Biogas slurry treatment: the biogas slurry in the biofiller oxidation pond is treated with activated sludge method for 2-4 days, and the bottom is aerated;

(4) Purify water quality: The water from the biological filler oxidation pond enters the biomimetic oxidation pond, and an ecosystem composed of artificial aquatic plants-algae-bacteria is set in the pond for further transformation and absorption, and the treatment time is 20-30 days;

(5) Deep purification: The water from the imitation ecological oxidation pond is pumped to the vertical submerged artificial wetland. The wetland adopts the PVC pipe frame water distribution mode, and the wetland plants use canna suitable for planting in the south. The wetland effluent can be directly discharged, and the hydraulic retention time HRT2-10 days.

The biogas produced in step (2) can be used for power generation, conservation, self-use or daily use by surrounding farmers.

The biological filler in the biological filler oxidation tank in step (3) is a black polyethylene shading net, which is arranged in the tank in the form of suspension and sinking; the aeration device is installed at the bottom, and the aeration rate is adjusted according to actual needs. The dissolved oxygen concentration is 2~4mg/L.

The artificial aquatic plants in step (4) are polyethylene shading nets, which are suspended in the pond in the form of suspension and sinking, and are used as an attachment base for algae-bacteria symbiosis.

Working principle of the present invention is:

After the aquaculture wastewater of the present invention is collected, it is transported to the regulating tank I described in step (1) by the pipeline. After the pretreatment feed liquid is separated and treated by the solid-liquid separator, the moisture content of the residue is not higher than 50%, and the TSS, The COD and BOD removal rates are not less than 80%, 60%, and 60% respectively; at the same time, the separated feed liquid is more homogeneous, which is beneficial to subsequent processing and improves the processing efficiency of the system as a whole.

In the biogas digester, under the decomposition of anaerobic microorganisms, the feed liquid decomposes macromolecular organic matter into small molecules, and anaerobic bacteria decompose organic matter to produce biogas. According to the role of various bacteria in the biogas fermentation process, biogas bacteria can be divided into decomposing bacteria and methane bacteria: decomposing bacteria decompose complex organic matter into simple organic matter and carbon dioxide (CO ₂ ); methane bacteria oxidize simple organic matter and carbon dioxide or reduced to methane. Organic nitrogen is converted into NH ₄ ⁺ -N; most organic phosphorus is absorbed by phosphorus accumulating bacteria and released into the feed solution in the form of phosphate radicals, which then combine with Ca ²⁺ and Mg ²⁺ ions to form phosphate Precipitated in the sludge; the sulfur in the organic matter is converted into H ₂ S gas by microorganisms and discharged with the biogas.

After the biogas slurry is discharged, it enters the adjustment tank II, where scum and sludge can be formed, which can reduce the TSS entering the biological filler oxidation tank, and at the same time allow natural reoxygenation. After the effluent from regulating tank II enters the biological filler oxidation tank, NH ₄ ⁺ -N can be oxidized to NO ₃ ^— -N and NO ₂ ^— -N after being treated with activated sludge, while NH ₄ ⁺ -N and NH ₄ ⁺ -N can be A short-range nitrification reaction occurs directly, and N is released in the form of N ₂ or N ₂ O. The effluent from the biological filler oxidation pond enters the imitation ecological oxidation pond, and the pollutants in the sewage are further transformed and absorbed by the ecosystem composed of artificial aquatic plants-algae-bacteria in the pond, so as to achieve the purpose of purifying water quality.

The effluent of the imitation ecological oxidation pond is pumped to the artificial wetland through the lifting pump, and the water is evenly distributed through the frame water distribution pipe. The sewage flows vertically downward from the surface of the wetland, forming a treatment system with surface aerobic, middle facultative and bottom anoxic. Constructed wetlands use an ecosystem composed of artificial media, plants, and microorganisms to carry out physical, chemical, and biological triple synergistic purification. Physical precipitation (filtration) makes sedimentable and flocculated solids It is blocked and removed; chemical microbial metabolism uses the metabolism of bacteria parasitic on plants to decompose suspended solids, colloids, and soluble solids into inorganic substances, and at the same time remove nitrogen through biological nitrification-denitrification, and convert N to N ₂ or N ₂ O form release. Some trace elements are oxidized by microorganisms and plants and removed by interception or combination. Bacteria and viruses will cause natural decay and death in an unsuitable environment. Plant root exudates can inactivate Escherichia coli and pathogens. A considerable amount of nitrogen and phosphorus can be absorbed and removed by plants. Perennial plants, harvested once a year, can move nitrogen and phosphorus out of the constructed wetland system.

The beneficial effects of the present invention are:

1. The process of the present invention is simple and has good applicability, and can fully meet the wastewater treatment requirements of planned pig farms in southern regions;

2. The treatment efficiency is high, and the effluent water quality after treatment by the process system is far lower than the discharge standard, meeting the advanced treatment requirements;

3. The investment cost is low, the process system is mainly based on the cost of geotechnical construction, and large and expensive equipment is urgently needed;

4. Low operating and management costs. During the operation, only the solid-liquid separator, aeration pump and wetland distribution pump consume electricity, and there is no other operating costs; the management is simple, and special personnel are needed for management. For example, the automatic control system can be increased to achieve Timing control of solid-liquid separator and water pump, lower management cost;

5. The process technology has high reliability, the system is stable and has a long service life.

Description of drawings

Fig. 1 schematic diagram of aquaculture wastewater treatment process;

Fig. 2 schematic diagram of aquaculture wastewater treatment process;

Among them, 1. Sewage collection pipe, 2. Regulating tank Ⅰ, 3. Solid-liquid separator, 4. Waste residue, 5. Biogas digester, 6. Regulating tank Ⅱ, 7. Aeration pipe, 8. Air pump, 9. Biological filler, 10. Biological filler oxidation pool, 13. Wetland water distribution pipe, 14. Wetland plants, 16. Outlet overflow port;

Fig. 3 cross-sectional view of aquaculture wastewater treatment process;

Among them, 1. Sewage collection pipe, 2. Regulating tank Ⅰ, 3. Solid-liquid separator, 4. Waste residue, 5. Biogas digester, 6. Regulating tank Ⅱ, 7. Aeration pipe, 9. Biofiller, 10. Biofiller Oxidation pond, 11. Imitation ecological oxidation pond, 12. Artificial aquatic plants, 13. Wetland water distribution pipe, 14. Wetland plants, 15. Wetland substrate, 16. Water outlet overflow, 17. Wetland water collection pipe.

Detailed ways

The present invention will be further described in detail by examples below, and these examples are only used to illustrate the present invention, and do not limit the scope of the present invention.

Example 1

(1) Wastewater pretreatment: Pig excrement and flushing water and other aquaculture wastewater are collected in the adjustment pool I through the collection pipe network, and a solid-liquid separator is installed beside the pool. After being treated by the separator, the feed liquid is divided into solid feces residue and feed liquid;

(2) Biogas slurry sedimentation: The feed liquid enters the biogas digester, and after 7 days of anaerobic fermentation, biogas and biogas slurry are formed, and the biogas slurry enters the adjustment tank II, and after 1 day of precipitation, scum and sludge are formed, and floating sludge on the scum The mud sinks, and the biogas slurry enters the biological filler oxidation tank;

(3) Biogas slurry treatment: The biogas slurry in the biofiller oxidation pond is treated with activated sludge method for 2 days, and the bottom is aerated to maintain the dissolved oxygen concentration at 2mg/L;

(4) Purify water quality: the effluent from the biological filler oxidation pond enters the imitation ecological oxidation pond, and an ecosystem composed of artificial aquatic plants-algae-bacteria is set in the pond for further transformation and absorption, and the treatment time is 20 days;

(5) Deep purification: The effluent of the imitation ecological oxidation pond is pumped up to the vertical submerged artificial wetland. The wetland adopts the PVC pipe frame water distribution mode. The wetland plants are planted with cannas suitable for planting in the south, planted at a distance of 30×30mm, and the wetland effluent can be directly Discharge, HRT2 days.

Example 2

(1) Wastewater pretreatment: Pig excrement and flushing water and other aquaculture wastewater are collected in the adjustment pool I through the collection pipe network, and a solid-liquid separator is installed beside the pool. After being treated by the separator, the feed liquid is divided into solid feces residue and feed liquid;

(2) Biogas slurry sedimentation: The feed liquid enters the biogas digester, and after 12 days of anaerobic fermentation, biogas and biogas slurry are formed, and the biogas slurry enters the adjustment tank II, and after 5 days of precipitation, scum and sludge are formed, and the floating sludge on the scum The mud sinks, and the biogas slurry enters the biological filler oxidation tank;

(3) Biogas slurry treatment: The biogas slurry in the biofiller oxidation pond is treated with activated sludge method for 10 days, and the bottom is aerated to maintain the dissolved oxygen concentration at 4mg/L;

(4) Purify water quality: the effluent from the biological filler oxidation pond enters the imitation ecological oxidation pond, and an ecosystem composed of artificial aquatic plants-algae-bacteria is set in the pond for further transformation and absorption, and the treatment time is not less than 30 days;

(5) Deep purification: The effluent of the imitation ecological oxidation pond is pumped up to the vertical submerged artificial wetland. The wetland adopts the PVC pipe frame water distribution mode. The wetland plants are planted with cannas suitable for planting in the south, planted at a distance of 30×30mm, and the wetland effluent can be directly Discharge, HRT8 days.

Example 3

(1) Wastewater pretreatment: Pig excrement and flushing water and other aquaculture wastewater are collected in the adjustment pool I through the collection pipe network, and a solid-liquid separator is installed beside the pool. After being treated by the separator, the feed liquid is divided into solid feces residue and feed liquid;

(2) Biogas slurry sedimentation: The feed liquid enters the biogas digester, and after 10 days of anaerobic fermentation, biogas and biogas slurry are formed, and the biogas slurry enters the adjustment tank II. After 3 days of precipitation, scum and sludge are formed, and the floating sludge on the scum The mud sinks, and the biogas slurry enters the biological filler oxidation tank;

(3) Biogas slurry treatment: The biogas slurry in the biofiller oxidation pond is treated with activated sludge method for 5 days, and the bottom is aerated to maintain the dissolved oxygen concentration at 3mg/L;

(4) Purify water quality: the effluent from the biological filler oxidation pond enters the imitation ecological oxidation pond, and an ecosystem composed of artificial aquatic plants-algae-bacteria is set in the pond for further transformation and absorption, and the treatment time is not less than 25 days;

(5) Deep purification: The effluent of the imitation ecological oxidation pond is pumped up to the vertical submerged artificial wetland. The wetland adopts the PVC pipe frame water distribution mode. The wetland plants are planted with cannas suitable for planting in the south, planted at a distance of 30×30mm, and the wetland effluent can be directly Discharge, HRT5 days.

Example 4

An intensive pig farm in Guangdong covers a total area of 100 mu, with an annual inventory of 5,000 pigs and a daily wastewater production of no more than 300 tons.

Project construction includes:

1. Regulating pool I, cylindrical, 5m in diameter, 6m deep;

2. Purchase a commercial solid-liquid separator with a residue production capacity of about 1 ton/hour;

3. Construct 6 biogas digesters, each 400m3;

4. Regulating pool II, L×B×H=40.0m×3.0m×3.2m, effective water depth 3.0m, HRT1d.

5. Biological filler oxidation tank, 4 small pool aeration oxidation tanks of L×B×H=20.0m×2.5m×3.2m are connected in series, with biological filler inside;

6. Imitation ecological oxidation pond: The imitation ecological oxidation pond treatment system with a total area of 4000m2, the average water depth is not less than 2m, and artificial aquatic plants are installed inside;

7. Constructed wetland, L×B×H=53.0m×30m×1m, use gravel with a particle size of 10-25mm as the matrix, add anti-seepage treatment to the bottom of the wetland, the depth of the matrix is not more than 80mm, set PVC water collection pipes at the bottom, and set up PVC water collection pipes on the surface of the wetland. The frame-type water distribution pipes are laid out with PVC pipes, and cannas are planted at a distance of 30×30mm.

Table 1 List of water quality of inflow and outflow of each treatment unit of the process system (unit: mg/L, except PH)

project COD _cr BOD ₅ SS NH ₄ ⁺ -N TP pH Inlet of pretreatment tank ≥20000 ≥8000 ≥10000 ≥800 - 6-9 Pretreatment pond effluent (digester inflow) ≤8000 ≤4000 ≤2000 ≤800 - 6-9 Digester effluent (sedimentation tank inflow) ≤1500 ≤800 ≤1200 ≤600 ≤80 6-9 Sedimentation tank effluent (aeration tank inflow) ≤1000 ≤600 ≤1000 ≤500 ≤70 6-9 Aeration tank effluent (oxidation pond inflow) ≤300 ≤100 ≤300 ≤100 ≤40 6-9 Oxidation pond effluent (wetland inflow) ≤150 ≤100 ≤50 ≤40 ≤20 6-9 wetland water ≤80 ≤50 ≤20 ≤20 ≤8 6-9

Claims (4)

1. A technique for advanced treatment of large-scale pig raising wastewater in the south, characterized in that: comprises the steps: (1) Wastewater pretreatment: Pig excrement and flushing water aquaculture wastewater are collected in the adjustment tank Ⅰ through the collection pipe network to form a feed liquid, and a solid-liquid separator is installed beside the pool, and the feed liquid is divided into solid feces residues after being treated by the separator material and separating liquid; (2) Biogas slurry sedimentation: The separated liquid enters the biogas digester, and after more than 7 days of anaerobic fermentation, biogas and biogas slurry are formed. The slag floats and the sludge sinks, and the biogas slurry enters the biological filler oxidation tank; (3) Biogas slurry treatment: the biogas slurry in the biofiller oxidation pond is treated with activated sludge method for 2-4 days, and the bottom is aerated; (4) Purify water quality: The water from the biological filler oxidation pond enters the biomimetic oxidation pond, and an ecosystem composed of artificial aquatic plants-algae-bacteria is set in the pond for further transformation and absorption, and the treatment time is 20-30 days; (5) Deep purification: The water from the imitation ecological oxidation pond is pumped to the vertical submerged artificial wetland. The wetland adopts the PVC pipe frame water distribution mode, and the wetland plants use canna suitable for planting in the south. The wetland effluent can be directly discharged, and the hydraulic retention time HRT2-10 days. 2. A process for advanced treatment of large-scale pig-raising wastewater in the south according to claim 1, characterized in that: the biogas generated in step (2) can be used for power generation, conservation, self-use or daily use by surrounding farmers. 3. A process for advanced treatment of large-scale pig raising wastewater in the south according to claim 1, characterized in that: the biological filler in the biological filler oxidation tank in step (3) is a black polyethylene shading net, according to the suspension and sinking The form is arranged in the pool; the aeration device is installed at the bottom, the aeration volume is adjusted according to actual needs, and the dissolved oxygen concentration is maintained at 2~4mg/L. 4. A process for the advanced treatment of large-scale pig-raising wastewater in the south according to claim 1, characterized in that: the artificial aquatic plants in step (4) are polyethylene shading nets, which are suspended in the pond according to the form of suspension and sinking. Attachment base for algae-bacteria symbiosis.