浸没式超滤膜在大型给水厂的应用与思考OACSTPCD

The production scales of two large water treatment plants(WTPs),J WTP and T WTP,in Zhejiang Province are 2.0×105 m3/d and 5.0×105 m3/d,respectively,with operation times of 2 years and 7 years.Both WTPs utilize submerged ultrafiltration membranes as the core water purification technology.Based on the actual operation of the two WTPs,this paper studied and summarized their operational management experiences as following regarding membrane operation,the daily inflow turbidity in both WTPs ranged from 0.15 NTU to 4.25 NTU,stabilizing below 0.1 NTU in finished water turbidity with occasional detection of particles over 2 μm,even at conditions of occasional short-term spikes of 13.6～35.2 NTU during typhoon seasons.In terms of membrane fouling control,both WTPs conducted air scouring during the middle stage of water production,effectively extending the water production time.For chemical cleaning,citric acid was found to be effective for J WTP,while a combination of sodium hypochlorite followed by citric acid was effective for T WTP.Regarding WTP design,pump-assisted production process of J WTP exhibits a relatively high overall energy consumption of 27 kW·h/km3,while T WTP,with its gravity-assisted production process,achieved a significantly lower energy consumption,as low as 13 kW·h/km3,effectively reducing energy consumption.In terms of operational management,increasing the clear water reservoir′s volume effectively resolved issues stemming from inadequate clear water reservoir storage capacity,which led to prolonged membrane overloading at J WTP.Simultaneously,the introduction of a chlorination point ahead of the membrane feedwater in the membrane tank ensured stable effluent residual chlorine levels of approximately 0.2 mg/L,efficiently addressing problems related to algal growth.