| Aiming at the problem of excessive total nitrogen in wastewater treatment of JA SOLAR Company,this paper analyses the characteristics of wastewater and the existing problems of wastewater treatment facilities,and puts forward the proposed scheme of upgrading wastewater treatment by upgrading the standard.Combining with the actual production in the plant area,the parameters of each process pool,operation control parameters and debugging and monitoring are calculated and designed.The feasibility and progressiveness of the transformation project are analyzed from two aspects of technology and economy.Through research,the following conclusions are reached:(1)The main wastewater of JA SOLAR Company is silicon wafer battery production process wastewater,waste gas treatment spray wastewater and employees’domestic wastewater.After the existing system treatment,the effluent fluoride ion concentration and SS concentration can meet the discharge standard,but the total nitrogen concentration of effluent is still up to 450 mg/L,which is difficult to meet the "Battery Industry Pollutant Discharge Standard"(GB30484-2013)total nitrogen emission index.The organic species of pollutants in the wastewater are complex,the total nitrogen content is high,the COD content is low,the nutrient ratio is imbalanced,and the fluoride content is high,which has a certain physiological toxic effect on microorganisms in water and affects the biochemical treatment effect.The water quality and quantity fluctuate greatly,and there is a shock load;(2)The original wastewater treatment process is "two-stage fluoride removal process + SBR biochemical tank".Because of the lack of denitrification environment,poor denitrification capacity,TN can not meet the standard.After upgrading,the "two-stage pre-anoxia + A/O"treatment process is proposed,and the A/O biological treatment process is anoxic + aerobic treatment process.Because of the low COD index and high concentration of total nitrogen and insufficient power of denitrification,the carbon source should be added.It is predicted that the removal rate of primary A/O and secondary A/O is 80%and 65%,respectively.It is predicted that the TN of effluent from the reformed water treatment system is 31.5 mg/L,which is less than the discharge standard requirement of 40 mg/L.The nitrogen removal efficiency can reach about 93%and the sewage can meet the discharge standard;(3)Through a month’s commissioning,the effluent of the whole system has reached the corresponding discharge standard.The secondary A/O system of biochemical system is also relatively stable at present.The removal rate of the first stage is between 70%and 80%.The second stage effluent has reached the discharge standard.The COD of the effluent is now stable at about 120 mg/L,the total nitrogen is 30 mg/L and the ammonia nitrogen is 25 mg/L.It shows that the removal rate of nitrate nitrogen is obvious,and the residence time of the whole denitrification reaction is enough.The dosage of glucose can be reduced appropriately to control costs.The indexes of each stage of A/O process should be strictly controlled,PH:6.5-8.5,DO of O stage should be controlled at 2-4 mg/L,DO of A stage should be≤ 0.3 mg/L,MLSS:3000-4000 mg/L,ORP:<250 mv;(4)The process adopted in this study is mature and stable,and the denitrification efficiency can reach 93%.The pre-A tank is a Pre-Anoxic tank,which can effectively reduce the dissolved oxygen of the digestive liquid refluxed from the aerobic tank,denitrify in the anoxic A tank and increase the denitrification efficiency.The filler is used in the secondary aerobic tank to effectively increase the sludge concentration and transport.The project utilizes the original civil pond body to carry out the transformation,and the cost of the pond body transformation is about 78.89 million yuan.In the later period,the operation cost is stable,including the cost of medicament,sludge treatment,electricity,equipment maintenance,labor and so on.The total cost is about 12.095 yuan/ton of sewage,and the operation cost is low. |
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