Study On ABR-SBR In The Treatment Of High-concentration Organic Wastewater From Nitrocellulose

In the production process of nitrocellulose,a large amount of high-concentration organic wastewater will be produced.If it is not properly treated,it will have a serious impact on the water environment.Therefore,it is of great significance to study the efficient treatment of such wastewater.This research is to solve the problem of wastewater treatment in a chemical plant in Henan.The wastewater is treated by coagulation sedimentation-ABR-SBR process,determining the optimal operating parameters of the coagulation and precipitation stage,studying the start-up process of the ABR reactor and SBR reactor and the operation effects of the two reactors under different influencing factors.The aim of the research is to discuss the feasibility of the combined process for treating such wastewater and offer the basis for engineering design.In the coagulation and sedimentation stage,the PAC,Al₂?SO₄?₃ and PAFC coagulants are optimized.The PAFC is determined as the best coagulant by comparative analysis.The optimal operating parameters of the coagulation and sedimentation stage are as follows:PAFC dosage is 500 mg/L,pH is 7.0,and precipitation time is 45 min.Under this condition,the COD removal rate can reach 31.5%,and the effluent turbidity is 30 NTU.The ABR reactor is stable after 146 days of start-up and domestication,the COD removal rate is above 40%,the effluent VFA concentration is kept below 130 mg/L,and the average effluent pH is 7.2.The optimum conditions of the reactor are determined as follows:the HRT is 8 days,the amount of NaHCO₃ in the influent is 0.2g/g COD,and the stirring method is intermittent stirring?5min/30min?.The ABR reactor stably operates for a period of time under the above conditions,the effluent COD decreases from 19900²0000 mg/L to 10000¹1000 mg/L,the removal rate is about 45%,and the effluent SS is 80⁹0 mg/L.The B/C value of the effluent increases from 0.3 to 0.5,which significantly improves the biodegradability of the wastewater.The nitrocellulose high-concentration organic wastewater treated by anaerobic reaction is mixed with the low-concentration acidic wastewater neutralized,and the mixed water COD is 470⁶00 mg/L,which is used as the influent of the SBR reactor.The SBR reactor is successfully started after 40 days,and the effluent COD is below 50mg/L,the SV is about 32%.The optimum working conditions of the SBR reactor are determined to be a temperature of 25°C,a sludge concentration of 3000 mg/L,an aeration time of 7 h,and a dissolved oxygen of 1.5 mg/L.Finally,the operating cycle of the SBR reactor is determined to be 8 h.The SBR reactor operates stably under optimal conditions for 10 days,the removal rate of COD is over 94%,the effluent COD<40mg/L,SS<10mg/L,and the effluent water quality is maintained within a stable range,reaching the local environmental standards in Henan.