Comparative coagulant demand of polyferric chloride and ferric chloride for the removal of humic acid

Abstract This paper is concerned with the potential advantages of the use of polyferric chloride as a coagulant for the removal of natural organic matter (e.g., humic acid) in water treatment. In particular, this paper assesses the effects of the basic nature of polyferric chloride, the type of water, and the coagulation pH on the humic acid removal performance. The comparative dose demand of polyferric chloride and ferric chloride was assessed in terms of a good humic acid removal efficiency (> 50%) achieved. It was found that a polyferric chloride with a basic ratio of 0.3 can achieve the best humic acid removal. The water having both humic acid and colloidal particles was favorable to the floc development and a better humic acid removal. For the same coagulation conditions, the dose demand of polyferric chloride was 50% less than that of FeCl3 for a > 50% humic acid removal.