The study explored the suitability of natural coagulants for pretreating surface water for ultrafiltration. We hypothesize that natural coagulants can be simple and inexpensive alternative to conventional coagulants in settings where specialized expertise and equipment are lacking. Coagulation performance of natural coagulants was quantified in terms of turbidity removal and concentration of residual organics. For high turbidity clay suspensions as the source water, the optimal coagulant dosage and flocculation mixing condition turbidity removal were similar to those recorded in reference tests with alum. The extraction process, however, allowed residual organics into the treated water. Thee organics can be removed by membrane filters installed downstream pointing to synergic benefits of combining natural coagulants with membrane filtration.
