Removal of 2-methylisoborneol and geosmin in surface water treatment plants in Arizona

Many utilities experience taste and odour episodes that affect the public's perception of the safety of drinking water. Two compounds responsible for earthy and musty taste and odours in drinking water supplies are geosmin and 2-methylisoborneol (MIB), which are produced by blue-green algae and actinomycetes. MIB and geosmin are typically removed in water treatment plants (WTPs) through the addition of powdered activated carbon (PAC) or strong oxidants. However, chemical addition can be costly and performance variable, depending on the water chemistry. Optimization of water treatment processes and chemical addition for removal of MIB and geosmin would be economically beneficial to utilities and provide a service to customers. Results from this research showed traditional water treatment processes (coagulation) could not be optimized for removal of MIB and geosmin. During ozonation, hydroxyl radicals accounted for a greater percentage of MIB or geosmin oxidation relative to molecular ozone oxidation. PAC adsorption experiments in Arizona drinking water showed that dissolved organic carbon competed with MIB and geosmin for PAC adsorption sites. Utilities should conduct taste and odour removal tests in local waters containing natural dissolved organic carbon and not rely on manufacturer data in ultra-pure water. Laboratory PAC experiments predicted full-scale PAC performance well.