REMOVAL OF TRIHALOMETHANE PRECURSORS FROM RIVER AND LAKE WATER BY ACTIVATED CARBON ADSORPTION

A comprehensive study was undertaken to clarify the method of reducing trihalomethane and its precursors from river and lake water in view of drinking water purification. Sources of water were chosen among lakes and rivers in Eastern Japan and biological treatment and coagulative precipitation of the water samples were carried out prior to activated carbon adsorption. A strong relation was shown between TOC and THMFP of raw and treated samples, and the relation changed due to the extent of biological treatment. Though the chemical structure of substances which may cause trihalomethane formation is not clear, the content of ammoniacal nitrogen is responsible for the reduction of trihalomethane formation produced by the addition of chlorine. However, this does not mean that the reduction of chlorine dose can be achieved simply by the process of biological treatment.