CN105036489B - Livestock/poultry culture wastewater deep denitrification and dephosphorization standard treatment device and process - Google Patents

Abstract

The invention discloses a standard-reaching treatment device for deep denitrification and dephosphorization of livestock and poultry breeding wastewater and a process thereof. Based on anaerobic fermentation technology, micro-oxygen aeration technology and nitrogen and phosphorus recovery technology, the present invention forms micro-oxygen aeration to reduce operating costs and strengthen denitrification and dephosphorization. Synchronous denitrification and carbon removal coupled with coagulation and crystallization dephosphorization up to standard Processing technology. The specific steps are: livestock and poultry breeding wastewater is firstly treated by solid-liquid separation, the waste residue is used to produce organic fertilizer, the wastewater is used as a resource to enter the UASB reactor, and biogas is produced through anaerobic fermentation; the high-concentration nitrogen and phosphorus anaerobic effluent enters the micro-aerobic aeration biochemical The reactor performs simultaneous denitrification and carbon removal; the biochemical effluent continuously enters the coagulation crystallization phosphorus removal clarifier for nitrogen and phosphorus recovery, and the crystalline solids containing nitrogen and phosphorus nutrients are used as raw materials for the production of organic fertilizers, and the clean water is discharged up to the standard. The invention has the advantages of good denitrification and carbon removal effect, high recovery and utilization rate of nitrogen and phosphorus resources, strong impact load resistance, low operation cost and easy popularization and application.

Description

A treatment device and process for deep denitrification and phosphorus removal of livestock and poultry breeding wastewater

technical field

The invention belongs to the field of environmental protection wastewater treatment, and in particular relates to a treatment device for deep denitrification and dephosphorization of livestock and poultry breeding wastewater up to standard and a process thereof.

Background technique

During the "Eleventh Five-Year Plan" period, the state carried out comprehensive treatment of rivers seriously polluted by agricultural non-point sources across the country, especially in the aspect of water pollution control of large-scale pig farming waste, and the concentration of COD _Cr in wastewater can basically achieve discharge standards . However, the concentration of nitrogen and phosphorus seriously exceeds the standard, which makes the nitrogen and phosphorus load of the water body received by the regional farms too large, resulting in eutrophication of the water body. During the "Twelfth Five-Year Plan" period, the state will focus on controlling the nitrogen and phosphorus pollution of large-scale aquaculture wastewater, strengthen the denitrification and phosphorus removal of wastewater, and minimize the pollutants discharged by regional aquaculture farms. With the introduction of the "Discharge Standards for Water Pollutants in Livestock and Poultry Breeding Industry" (the second consultation draft in 2014), the wastewater discharge standards will be raised to COD _Cr 150 mg/L, ammonia nitrogen 40 mg/L, total nitrogen 70 mg/L and The total phosphorus is 5mg/L, and the existing wastewater treatment process of large-scale pig farms is difficult to discharge the wastewater up to the standard. It is urgent to develop advanced high-efficiency and low-consumption livestock and poultry breeding wastewater treatment process facilities. Therefore, starting from the requirements of standard upgrading and improving the water environment quality in the surrounding area, it is urgent to upgrade the existing processes and devices, focusing on improving the efficiency of nitrogen and phosphorus removal, so as to reduce the impact of the tail water treated by the farm on the surrounding ecological environment .

At present, the combined treatment process of anaerobic fermentation-aerobic-oxidation pond/constructed wetland is the mainstream technology for large-scale pig farm wastewater treatment in my country, but the key problem of this process is the low carbon-nitrogen ratio pig farm after anaerobic fermentation treatment. In the subsequent aerobic biological treatment of the digested liquid of aquaculture wastewater, there are problems such as poor removal of organic pollutants, low efficiency of nitrogen and phosphorus removal, high operating costs, and large footprint. A large number of studies have shown that the NH ₄ ⁺ -N removal rate of anaerobic digestion liquid of pig farm wastewater by SBR process, contact oxidation method and intermittent aeration activated sludge method is only 40-68%, and the removal rate of TN is only 30%. Existing actual projects show that the anaerobic fermentation-aerobic-oxidation pond/constructed wetland combination treatment process has a good removal effect on COD and SS, but has no significant effect on nitrogen and phosphorus removal, and the resource recovery rate is low, making it difficult to Realize the recycling of pig farm waste resources and the stable and up-to-standard discharge of breeding wastewater. In order to solve the wastewater pollution of large-scale pig farms and realize the reduction of pollutants, it is urgent to develop high-efficiency and low-consumption treatment technologies suitable for high-concentration nitrogen and phosphorus pig farm wastewater.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, provide a treatment device for the deep denitrification and phosphorus removal of livestock and poultry breeding wastewater, promote the implementation of standard upgrading and transformation of the pig farm wastewater treatment process, strengthen the denitrification and phosphorus removal, and improve resource recycling and utilization High efficiency, reduced operating costs, and minimized pollutants from large-scale pig farming wastewater entering the river.

The concrete technical scheme that the present invention adopts is:

A standard treatment device for deep nitrogen and phosphorus removal of livestock and poultry breeding wastewater, including: raw water collection tank, UASB reactor, water distribution tank, pre-denitrification tank, micro-oxygen aeration tank, sedimentation tank and coagulation crystallization phosphorus removal clarifier , the outlet pipe of the raw water collection tank is divided into two lines, one line is connected to the water inlet of the UASB reactor through the grille, and the other line is connected to the water outlet of the UASB reactor and then connected to the water inlet of the water distribution tank, and the water distribution tank is sequentially connected to the pre-denitrification tank, micro-oxygen aeration tank, sedimentation tank and coagulation crystallization phosphorus removal clarifier are connected; there is a sludge return pipe at the bottom of the sedimentation tank, and the other end of the sludge return pipe is connected to the pre-denitrification tank; water distribution tank, pre-denitrification Stirring devices are installed in the coagulation and crystallization dephosphorization clarifier; fillers are installed in the middle of the pre-denitrification tank, and water distribution devices are installed at the bottom; aeration devices are installed at the bottom of the micro-oxygen aeration tank.

Preferably, the aeration device is a microporous aeration tube, and the filler is an elastic filler.

Another object of the present invention is to provide a treatment process for advanced denitrification and dephosphorization of livestock and poultry breeding wastewater using the device, comprising the following steps:

1) After solid-liquid separation, the raw water of livestock and poultry wastewater is pumped into the UASB reactor, and biogas is generated through anaerobic fermentation;

2) The wastewater and raw water treated in step 1) are mixed at a ratio of (0.8-1.2): 1. After the water is mixed, it is pumped into the micro-aerobic aeration synchronous denitrification and carbon removal reactor, and the reactor flows through the pre-denitrification tank in turn. , micro-oxygen aeration tank and sedimentation tank; in the pre-denitrification tank, the denitrifying bacteria use easily degradable carbon sources as electron donors, and the nitrate nitrogen and nitrite nitrogen returned from the sedimentation tank serve as electron acceptors. Denitrification is carried out through denitrification; in the micro-oxygen aeration tank, the dissolved oxygen concentration of the wastewater is controlled at 0-0.15mg/L, so that the microorganisms in the wastewater can perform short-range nitrification and synchronous nitrification and denitrification; in the sedimentation tank, Wastewater is separated from sludge and water, and part of the sludge is returned to the pre-denitrification tank to provide nitrate nitrogen and nitrite nitrogen as electron acceptors for denitrification bacteria, and the remaining sludge is discharged regularly;

3) The supernatant after the separation of sludge and water in step 2) is discharged into the coagulation and crystallization dephosphorization clarifier, and PFS and PAM are added into the clarifier, mixed with the wastewater evenly for deep denitrification and dephosphorization, and the treated clean water is discharged up to the standard.

Preferably, the biogas obtained in step 1) is collected and purified for power generation, and the generated electric energy is used to power the equipment in step 2).

Preferably, the biogas residue produced by anaerobic fermentation in step 1) and the crystalline solid produced by deep denitrification and phosphorus removal in step 4) are used as raw materials for producing organic fertilizer.

As a preference, the hydraulic retention time of the UASB reactor in step 1) is 15 days.

As a preference, in the microaerobic aeration synchronous denitrification and carbon removal reactor in step 2), the hydraulic retention time of the wastewater in the pre-denitrification tank, microaerobic aeration tank and sedimentation tank are respectively 0.625 days and 4.0 days and 0.625 days.

As a preference, in the microaerobic aeration synchronous denitrification and carbon removal reactor in step 2), the sludge reflux ratio of the sedimentation tank is 3 times of the influent flow rate of the pre-denitrification tank.

As a preference, the hydraulic retention time of the coagulation and crystallization phosphorus removal clarifier in step 3) is 4 hours, and its operation mode is continuous.

As a preference, the dosage of PFS in the coagulation and crystallization phosphorus removal clarifier described in step 3) is 1.0 mL/L wastewater, and the dosage of PAM is 2.5 mL/L wastewater.

The present invention has the following advantages:

(1) The effluent water quality of the process of the present invention is good, the total hydraulic retention time is short, and the occupied area is small. The present invention only uses UASB + micro-oxygen aeration synchronous denitrification and carbon removal system + coagulation depth denitrification and phosphorus removal system to realize the deep purification of pig farm wastewater. Footprint and total hydraulic retention time. The wastewater from large-scale pig farms undergoes a multi-level combined treatment process, so that the quality of the effluent can be stabilized to meet the discharge requirements of the "Discharge Standards for Pollutants in the Livestock and Poultry Farming Industry" (Second Draft for Comment in 2014), achieving standard upgrading.

(2) Micro-aerobic aeration synchronous and efficient denitrification and carbon removal system has the characteristics of high denitrification and carbon removal efficiency, strong impact load resistance, low operating cost, and convenient operation and management. ① The micro-aerobic aeration synchronous high-efficiency nitrogen and carbon removal reactor has a COD _Cr removal rate of up to 90%, a total nitrogen removal rate of up to 90%, and a total phosphorus removal rate of about 70%. The main pollutants COD _Cr , total nitrogen and total phosphorus in pig farm wastewater can be removed very effectively in this unit. ② Utilize the micro-aerobic aeration biochemical reactor sludge backflow to ensure the high sludge concentration of the anaerobic denitrification tank treatment unit in the system, keep the water flow circulating, strengthen the mud-water contact, and strengthen the synchronous denitrification and carbon removal function. The system has Strong resistance to shock loads. ③ The micro-oxygen aeration system uses a dissolved oxygen controller to automatically control the dissolved oxygen concentration in the system to realize synchronous short-range nitrification and denitrification, with high denitrification efficiency and convenient operation and management. ④Because the system adopts micro-oxygen aeration, compared with pure oxygen aeration, the aeration volume can be reduced by 25%, effectively reducing operating costs.

(3) The present invention adopts physical and chemical coagulation and crystallization, which can effectively remove the nitrogen and phosphorus content of aquaculture wastewater, and the obtained coagulation crystal precipitation can be used as fertilizer. Physicochemical coagulation can perform deep denitrification and phosphorus removal of wastewater, and at the same time, it can realize the recovery of wastewater nutrients and realize the resource utilization of aquaculture wastewater. In addition, because the coagulation and crystallization dephosphorization clarifier of this process uses a relatively small amount of chemicals, it can reduce the cost of chemicals in the coagulation system.

(4) The present invention has higher efficiency of denitrification and dephosphorization of the low-carbon nitrogen than biogas slurry after anaerobic fermentation of livestock and poultry breeding wastewater, and no additional carbon source and alkalinity are required.

(5) The resource utilization rate of pig farming waste in the present invention is high. The biogas produced by anaerobic fermentation is used for power generation, and the electric energy produced is supplied to the power equipment of the micro-aerobic aeration synchronous denitrification and carbon removal reactor, so as to realize energy recycling and reduce operating costs. At the same time, waste residues from solid-liquid separation, biogas residues from anaerobic fermentation, and coagulation crystalline solids can be used as raw materials for the production of organic fertilizers, maximizing the recycling rate of farming waste resources.

Description of drawings

Fig. 1 is a structural schematic diagram of a treatment device for deep denitrification and dephosphorization of livestock and poultry breeding wastewater;

Fig. 2 is a flow chart of a treatment process for advanced denitrification and phosphorus removal of livestock and poultry breeding wastewater.

In the figure: Raw water collection tank 1, UASB reactor 2, water distribution tank 3, pre-denitrification tank 4, micro-oxygen aeration tank 5, sedimentation tank 6, coagulation and crystallization phosphorus removal clarifier 7, filler 8, water distribution Device 9, aeration device 10 and grid 11.

detailed description

Below in conjunction with accompanying drawing and specific example the present invention is described in further detail:

As shown in Figure 1, a treatment device for advanced denitrification and phosphorus removal of livestock and poultry wastewater includes: raw water collection tank 1, UASB reactor 2, water distribution tank 3, pre-denitrification tank 4, and micro-oxygen aeration tank 5 , sedimentation tank 6 and coagulation and crystallization dephosphorization clarifier 7, the outlet pipeline of raw water collection tank 1 is divided into two routes, one route is connected to the water inlet of UASB reactor 2 through the grid 11, and the other route is connected to the outlet of UASB reactor 2 After confluence, it is connected with the water inlet of the water distribution tank 3, and the water distribution tank 3 is connected with the pre-denitrification tank 4, the micro-oxygen aeration tank 5, the sedimentation tank 6 and the coagulation and crystallization phosphorus removal clarifier 7 in turn; the bottom of the sedimentation tank 6 is provided with a sewage Sludge return pipe, the other end of the sludge return pipe is connected to the pre-denitrification tank 4; the water distribution tank 3, the pre-denitrification tank 4 and the coagulation and crystallization phosphorus removal clarifier 7 are equipped with stirring devices; the middle part of the pre-denitrification tank A filler 8 is provided, and the filler 8 adopts an elastic filler. A water distribution device 9 is provided at the bottom of the pre-denitrification tank. An aeration device 10 is arranged at the bottom of the micro-oxygen aeration tank, and the aeration device 10 is a microporous aeration tube. In this system, the pre-denitrification tank 4, the micro-oxygen aeration tank 5, and the sedimentation tank 6 constitute a micro-oxygen aeration synchronous denitrification and carbon removal reactor

Taking the wastewater treatment process of a large-scale breeding pig farm in Yuhang District, Hangzhou City, Zhejiang Province as an example, the above-mentioned device is used to treat the pig farm wastewater. The raw water and anaerobic fermentation water quality are shown in Table 1:

Table 1 Wastewater quality of a large-scale breeding pig farm in Hangzhou

Unit: mg/L (except pH value)

The specific process of the inventive method is shown in Figure 2. 150 tons of pig farm wastewater is separated from solid and liquid by grids, and the separated wastewater is pumped into the UASB reactor for anaerobic fermentation reaction. The biogas generated during the anaerobic fermentation process is collected and purified. After processing, it is used to generate electricity, and the generated electricity is used to supply energy to the equipment in the system. After 15 days of reaction in the UASB reactor, the COD concentration can be reduced to about 2500 mg/L. After the anaerobic reaction, the anaerobic effluent and raw water are mixed according to the ratio of 1:1, and then pumped into the pre-denitrification tank of the micro-aerobic aeration synchronous denitrification and carbon removal system. Three times of the influent flow is returned to the pre-denitrification tank. In the pre-denitrification tank, the nitrate nitrogen and nitrite nitrogen returned from the sedimentation tank are denitrified, denitrified and decarbonized using easily degradable carbon sources, and the dissolved oxygen concentration in the micro-oxygen aeration tank is controlled by an online dissolved oxygen meter. 0-0.15 mg/L, realizing short-cut nitrification and simultaneous nitrification and denitrification, and the whole system does not need an external carbon source. During stable operation, the effluent COD concentration of the simultaneous denitrification and carbon removal reactor is less than 300 mg/L, the effluent ammonia nitrogen concentration is less than 10 mg/L, the effluent total nitrogen concentration is less than 60 mg/L, and the effluent total phosphorus concentration is less than 15 mg/L. The corresponding removal rates were 87%-94%, 97%-99%, 90%-95% and 65%-70%. The biochemical effluent from the micro-aerobic aeration reactor enters the sedimentation tank to separate the wastewater from mud and water, and part of the sludge flows back to the pre-denitrification tank to provide nitrate nitrogen and nitrite nitrogen for it, and the remaining sludge is discharged regularly. The supernatant of the sedimentation tank enters the deep coagulation denitrification and phosphorus removal clarifier continuously through self-flow. PFS and PAM are pumped into the clarifier through a metering pump and mixed by a stirrer. The hydraulic retention time of the coagulation and crystallization dephosphorization clarifier is 4 Hours, its mode of operation is continuous. After precipitation, the crystalline solid sinks to the bottom and is discharged through the sludge discharge system. The waste residue separated from solid and liquid and the biogas residue produced by anaerobic fermentation are used as raw materials for the production of organic fertilizer. The dosage of PFS and PAM were 150L/day and 375L/day respectively. At the same time, deep nitrogen and phosphorus removal can be realized in the coagulation unit, COD can also be further effectively removed, the removal rate reaches about 50%, the removal rate of total nitrogen is about 20%, and the removal rate of total phosphorus is greater than 95%. The final effluent COD of the process of the present invention is ≤150 mg/L, ammonia nitrogen ≤25 mg/L, total nitrogen ≤40 mg/L, and total phosphorus ≤3.0 mg/L, which can meet the "Livestock and Poultry Breeding Pollutant Discharge Standard" (2014 The second consultation draft of the year) emission requirements.

The specific treatment effect of this process on the above wastewater is shown in the table below

Table 2 Influent and effluent water quality of wastewater treatment process

It can be seen that the device and process of the present invention have higher treatment efficiency for denitrification and phosphorus removal of livestock and poultry wastewater, and compared with the prior art, it has outstanding substantive features and significant progress.

Claims (9)

1. A standard treatment process for deep nitrogen and phosphorus removal of livestock and poultry breeding wastewater, characterized in that the treatment device used includes: raw water collection tank, UASB reactor, water distribution tank, pre-denitrification tank, micro-oxygen aeration tank , sedimentation tank, coagulation and crystallization dephosphorization clarifier, and the outlet pipeline of the raw water collection tank is divided into two routes, one of which is connected to the water inlet of the UASB reactor through the grille, and the other is connected to the outlet of the UASB reactor and then enters the water distribution tank The water outlet is connected, and the water distribution tank is connected with the pre-denitrification tank, micro-aerobic aeration tank, sedimentation tank and coagulation and crystallization phosphorus removal clarifier in turn; there is a sludge return pipe at the bottom of the sedimentation tank, and the other end of the sludge return pipe is connected to the front Denitrification tank; stirring device is installed in the water distribution tank, pre-denitrification tank and coagulation and crystallization phosphorus removal clarifier; filler is installed in the middle of the pre-denitrification tank, and water distribution device is installed at the bottom; the bottom of the micro-oxygen aeration tank An aeration device is provided; the treatment process includes the following steps: 1) After solid-liquid separation, the raw water of livestock and poultry wastewater is pumped into the UASB reactor, and biogas is generated through anaerobic fermentation; 2) The wastewater and raw water treated in step 1) are mixed at a ratio of (0.8-1.2): 1. After the water is mixed, it is pumped into the micro-aerobic aeration synchronous denitrification and carbon removal reactor, and the reactor flows through the pre-denitrification tank in turn. , micro-oxygen aeration tank and sedimentation tank; in the pre-denitrification tank, the denitrifying bacteria use the carbon source as the electron donor, and the nitrate nitrogen and nitrite nitrogen returned from the sedimentation tank serve as the electron acceptor. Nitrification is used for denitrification; in the micro-oxygen aeration tank, the dissolved oxygen concentration of the wastewater is controlled at 0-0.15mg/L, so that the microorganisms in the wastewater can perform short-range nitrification and synchronous nitrification and denitrification; in the sedimentation tank, the wastewater is denitrified The sludge and water are separated, and part of the sludge is returned to the pre-denitrification tank to provide nitrate nitrogen and nitrite nitrogen as electron acceptors for the denitrification bacteria, and the remaining sludge is discharged regularly; 3) The supernatant after the separation of sludge and water in step 2) is discharged into the coagulation and crystallization dephosphorization clarifier, and PFS and PAM are added into the clarifier, mixed with the wastewater evenly for deep denitrification and dephosphorization, and the treated clean water is discharged up to the standard. 2. The treatment process for deep denitrification and phosphorus removal of livestock and poultry breeding wastewater according to claim 1, characterized in that, the aeration device is a microporous aeration tube, and the filler is an elastic filler. 3. The treatment process for deep denitrification and phosphorus removal of livestock and poultry breeding wastewater according to claim 1, characterized in that the biogas obtained in step 1) is collected and purified for power generation, and the produced electric energy is given to The equipment in step 2) is powered. 4. The livestock and poultry breeding wastewater treatment process for deep denitrification and phosphorus removal according to claim 1, characterized in that the biogas residue produced by anaerobic fermentation in step 1) and the deep denitrification in step 3) The crystalline solids produced by nitrogen and phosphorus removal are used together as raw materials for the production of organic fertilizers. 5. The livestock and poultry breeding wastewater treatment process for deep denitrification and phosphorus removal according to claim 1, characterized in that the hydraulic retention time of the UASB reactor in the step 1) is 15 days. 6. The treatment process for advanced denitrification and phosphorus removal of livestock and poultry breeding wastewater according to claim 1, characterized in that, in the micro-aerobic aeration synchronous denitrification and carbon removal reactor in the step 2), the wastewater is first The hydraulic retention time of the denitrification tank, micro-aerobic aeration tank and sedimentation tank were 0.625 days, 4.0 days and 0.625 days respectively. 7. A treatment process for advanced denitrification and phosphorus removal of livestock and poultry breeding wastewater according to claim 1, characterized in that, in the micro-aerobic aeration synchronous denitrification and carbon removal reactor in the step 2), the sedimentation tank The return ratio of the sludge is 3 times of the influent flow of the pre-denitrification tank. 8. A treatment process for advanced denitrification and dephosphorization of livestock and poultry breeding wastewater according to claim 1, characterized in that the hydraulic retention time of the coagulation and crystallization dephosphorization clarifier in the step 3) is 4 hours, wherein The mode of operation is continuous. 9. A treatment process for advanced denitrification and dephosphorization of livestock and poultry breeding wastewater according to claim 1, characterized in that the dosage of PFS in the coagulation and crystallization dephosphorization clarifier described in step 3) is 1.0 mL /L wastewater, the dosage of PAM is 2.5 mL/L wastewater.