| The "partial nitrosation-anaerobic ammonium oxidation" process is a new type of denitrification process in recent years,which saves energy and has a small footprint and can save a lot of resources.However,anaerobic ammonium oxidation strictly requires the influent NO2--N/NH4+-N to be 1.32:1.At the same time,the winter temperature in the north is low,and the traditional partial nitrosation stage uses flocculent sludge.The sludge sedimentation performance is poor at low temperature,the sludge expansion loss is serious,and the effluent water quality cannot meet the water inlet requirement of the anaerobic ammonium oxidation stage.Therefore,it is particularly important to maintain partial nitrosation stability at low temperatures.In this experiment,the SBR reactor was used to inoculate the flocculent sludge to form aerobic granular sludge,which was then domesticated into a part of nitrosated granular sludge,and finally gradually reduced to low temperature for intensive culture.During the cooling process,by controlling the aeration time and the SBR reactor operating cycle to maintain the ratio of NO2--N/NH4+-N,the partial nitrosation efficiency is the best.At 15?,additive of fly ash in the reactor within 50mg/L,100mg/L,150mg/L,200mg/L,250mg/L,300mg/L,determine the amount of additive of fly ash for part of the influence of nitrification efficiency.This paper mainly draws the following conclusions.(1)As the temperature decreases,a partial nitrosation effect can be maintained by controlling the duration of the aeration and the reaction cycle.At 25?,the aeration period was 3.4h,the operating period was 4 h,and the effluent NO2--N/NH4+-N was maintained at 1.0:1.At 20?,the aeration period was 2.4h,the operating period was 3h,and the effluent NO2--N/NH4+-N was maintained at 0.73:1.At 15?,the aeration time was 2.65h,the operating period was 3h,and NO2--N/NH4+-N was maintained at 0.55:1.The partial nitrosated granular sludge cultured increased the volumetric load of ammonia nitrogen removal from 0.24 kg/(m3·d)to 0.35 kg/(m3·d)at 15? compared with 30?.(2During the continuous dosing process of 50mg/L?300mg/L fly ash,the sludge concentration in the reactor gradually increased,the effluent SS gradually decreased,and the sludge settling performance was strengthened.Compared with no fly ash,when the dosage is 250mg/L,the nitrite nitrogen accumulation rate is increased from 75%to 85%,and the ammonia nitrogen volume removal load is increased from 0.35kg/(m3·d).It is 0.45kg/(m3·d).The effluent NO2--N/NH4+-N reached 1.20:1 from 0.55:1,and the partial nitrosation effect was significantly improved.However,when the dosage continued to increase,part of the nitrosation will be converted to nitrosation,and the ammonia nitrogen removal rate will be 61%rose to 75%.(3)The overall test results show that when the reactor is operated at 15? for 2.65h,the operation period is 3 h,and the aeration rate is 0.2 L/min,it is effective to add 250mg/L of fly ash to the reactor.Improve the partial nitrosation efficiency,so that the effluent NO2--N/NH4+-N meets the hydration requirements of anaerobic ammonium oxidation. |
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