Behavior of off-flavour Compounds in the Raw Water of Lake Biwa and Its Treatment

A few, off-flavour problems are occurring every year conceming the water supply system of Kyoto City, Japan. In our research three species of filamentous blue-green algae have been identified as playing important roles in producing geosmin and 2-methylisoborneol (MIB) in Lake Biwa. These odorous compounds were found being stored in trichomes mainly, so the majority of those compounds can be removed from water during rapid sand filtration. In our water supply system, water purification has been executed based on the above pri nciple and we are obtaining favorable for removing those off-flavour troubles.