Impact of coagulation pH on enhanced removal of natural organic matter in treatment of reservoir water

Effect of coagulation pH on enhanced removal of NOM in treatment of reservoir water for drinking purposes has been investigated in this study. Raw water was collected at a local Waterworks of Singapore. Trials with different coagulation pHs and alum dosages were conducted in jar tests. NOM removal showed an up-and-down trend with increasing coagulation pH. The results showed that the optimum conditions for NOM removal were observed at a pH 5.2 and at alum dosage of 5 mg (Al)/L. NOM (in terms of DOC) removal of up to 45% and turbidity removal at 97% were noted during the tests conducted at the optimal conditions while NOM removal was 35% at the conventional coagulation pH 7.2. It was concluded that control of coagulation pH was critical for NOM removal in treatment of the reservoir water.