The removal of colloid and dissolved phosphorus by coagulation and membrane microfiltration

Micro-filtration has its limitation to remove the dissolved matter and colloids which are smaller than the membrane pore size. Experiments were conducted to develop a preliminary methodology to optimize the operating conditions of membrane hybrid system (coagulation - membrane micro-filtration) in comparing with the removal of colloidal particles and dissolved phosphorus which are presented in water in particle and dissolved forms, respectively. The results showed that the coagulant dosage could be minimized and high removal efficiency obtained in treating water with colloid particles only. However, for dissolved phosphorus, its removal efficiency is dependent on water alkalinity as well as coagulant dosage and the associated sludge production could not be minimized. To determine the minimum coagulant dosage for the removal of colloidal particles, a few tests of membrane hybrid system were needed. But, to remove dissolved phosphorus, jar test was the only process required to determine the coagulant dosage for meeting effluent standards.