A NEW STRATEGY FOR START-UP AND FILTER BACKWASH FOR ULTRA-LOW TURBIDITY WATER TREATMENT

摘要

A new start-up technique with short-term coagulant addition and optimization of the backwash procedure for ultra-low turbidity water treatment was performed. The results show that for influent turbidity in the range of0.14 to 0.32 NTU, the effluent turbidity can be reduced to below 0.1 NTU within 30 min through the optimization of the backwash procedure with a low flow rate. Moreover, with the further dosage of an additional 0.2 mg/L poly aluminum ferric chloride (PAFC) immediately after backwashing for approximately 12 min, the effluent turbidity can be reduced to 0.1 NTU and maintained below 0.1 NTU until approximately 48 h of filtering without using additional coagulant. The new technique not only can shorten the filter ripening period and enhance the water quality but also can decrease the consumption of coagulant and lower the operating costs.