The combination of coagulation and ozonation as a pre-treatment of ultrafiltration in water treatment.

Ultrafiltration (UF) technology is considered an efficient water treatment method. In recent years, researchers have been committed to enhancing the treatment efficiency of UF and alleviating membrane fouling. An effective method is to achieve this is through the use of coagulation as a pre-treatment to UF; however, during a long term operation, membrane fouling can occur due to the residual organic matters and the generation of microorganisms. In this study, we combine coagulation and ozonation as a pre-treatment of UF and compare four types of pre-treatment: coagulation, ozonation, coagulation followed by ozonation (C-O) and ozonation followed by coagulation (O-C). Results showed that ozonation alone did not perform well. Both combinations of coagulation and ozonation enhanced the organic matter removal efficiency, although membrane fouling was lowest following the C-O pre-treatment as the microbial load was reduced. While a slight increase in the yield of disinfection by-products was observed with the addition of ozonation, the concentration remained below the Chinese standard for tap water quality (100 μg/L).