Behaviour of Inorganic Coagulants in Secondary Effluents from a Conventional Wastewater Treatment Plant

摘要

An experimental laboratory scale study was conducted to compare the effectiveness of three inorganic coagulants-aluminium sulphate,ferric chloride and polyaluminium chloride (PAC)-in reducing the turbidity of secondary effluents form a conventional wastewater treatment plant.For each inorganic most appropriate coagulant,its dose and the optimal operational conditions to obtain the reaquired water quality (3-5 NTU) of rre-use in agricultural drip irrigation systems.PAC was identified as the most suitable coagulant/flocculant for reducing the turbidity of this type of water.The optimal conditions corresponded to pH6 and a dose of PAC of 20mg/l,but the recommended conditions are 50 mg/l for pH 8(the initial pH of the water) to obtain a turbidity reduction of 90%,which is independent of the initial turbidity of water(e.e.5-32 NTU).