Methods to control bio-fouling, i.e. UV-irradiation and chlorination pretreatment were evaluated in dead-end membrane filtration. Pilot-scale experiments were carried out at Kosuzume Water Purification Plant, which is located at the Sagami River in Kanagawa Prefecture, Japan. As a result, both UV-irradiation and chlorination strongly suppressed the increase of transmembrane pressure and prevented bio-fouling. However, in the case of pre-chlorination, the membrane color changed from white to brown after a long use, causing irreversible membrane fouling due probably to manganese adsorption. Suspended solids removal by membrane filtration decreased the formation potential for CHCl3, but didn't affect the CHCl2Br and CHClBr2 formation potentials. Pre-chlorination, however, increased both CHCl2Br and CHClBr2 formation potentials, thus making up for the reduction in CHCl3 formation potential due to membrane filtration. UV-irradiation pretreatment combined with membrane filtration in the water purification process is regarded as an accessible method and was proved effective in controlling bio-fouling, which gave us a better water quality without increasing trihalomethanes in contrast to pre-chlorination.

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