TRIHALOMETHANE FORMATION IN CHEMICAL CLEANING WATER OF CERAMIC MEMBRANE BY SODIUM HYPOCHLORITE

Abstract

At present, ceramic membrane filtration is one of the best promising technologies having been received intensive attention. However, the major problem in membrane filtration is membrane fouling which lead to degradation of filtrated water quality. In this study, Trihalomethanes formation in chemical soaking investigation was the main objective. Ping River water was used as feed raw water in the ceramic membrane filtration. Physical backwashing and chemical soaking were conducted to remove foulants which coated in ceramic membrane surface. The results showed the organic matter was the main cause of ceramic membrane fouling. Sodium hypochlorite (NaOCl) was used for organic matter removal during chemical soaking experiment. However, the chlorine can react with organic matter to form Trihalomethanes (THMs), which is a carcinogen. THMs formation by using sodium hypochlorite (NaOCl) in chemical soaking water was investigated. In the experiment, sixteen fouled membranes were soaking in the various conditions. The concentration of NaOCl was varied at 2,000, 3,000, 4,000 and 5,000 mg/L and each concentration was varied with different soaking times at 6, 8, 10 and 12 hours, respectively. THMs were found in every condition and increased with the increasing of NaOCl concentration. The highest THMs concentration is 887.59µg/L which obtained at 5,000 mg/l of NaOCl concentration with 12 hours of soaking time. From this study, THMs formed in every condition, so chemical soaking water could be treated or should be studied for appropriate treatment technology. The effects of sodium hypochlorite (NaOCl) concentration and soaking time on the flux recovery of fouled ceramic membrane were also investigated. The results showed that the highest efficiency of flux recovery is 69.68% which obtained at 5,000 mg/l of NaOCl concentration with 12 hours of soaking time.