COAGULATION, FLOCCULATION, SETTLING AND DEPTH FILTRATION – UV/CHLORINE PROCESS FOR GREYWATER REUSE

Abstract

Greywater reuse for non-potable purposes has been considered and used by various countries to help alleviate water scarcity challenges. This is particularly important for a water-stressed country like Singapore. The treated greywater can be used for toilet flushing, washing, and irrigation purposes. This study investigates the current greywater treatment technologies used and proposed a suitable treatment method for the application in Singapore. A ultraviolet (UV) based advanced oxidation process (AOP), UV/chlorine process, was used to investigate the feasibility of treating greywater. Pre-treatment methods such as coagulation, flocculation, and settling, and depth filtration was adopted to enhance the efficiency of the UV AOP system. The overall system achieved turbidity, total organic carbon, total coliform, and E. coli removal efficiency of 95.5%, 95.4%, 99.9%, and undetectable levels, respectively. Since the treated greywater meets the greywater reuse standards, the proposed treatment train was proven as a feasible option for greywater reuse in Singapore.