UV and UV/H2O2 treatment of methylisoborneol (MIB) and geosmin in water

The presence of taste and odour-causing compounds in water can lead consumers to perceive the water as unsafe and thus is a great concern for water utilities. This study examined the effectiveness of direct ultraviolet (UV) photolysis and the UV/hydrogen peroxide (H2O2) advanced oxidation process (AOP) for removing methylisoborneol (MIB) and geosmin from raw source water and treated water. LOW Pressure (LP) and Medium Pressure (MP) direct UV photolysis removed 10% and 25-50% of the compounds by 1000 mJ cm(-2) UV fluence, respectively. The addition of H2O2 created advanced oxidation conditions, and oxidized greater than 70% of these compounds at a UV fluence of 1000 mJ cm(-2). MP UV + H2O2 was consistently faster than LP UV + H2O2 for MIB oxidation, but water quality affected both of the UV + H2O2 AOPs. The UV + H2O2 AOP oxidation of these taste and odour contaminants in natural waters was effectively modelled using the steady state OH radical concentration model. Finally, electrical energy per order (EEO) values for oxidation of MIB and geosmin were determined for a model UV reactor, and indicated that the UV + H2O2 AOP requires less than 5 kWh of UV energy to oxidize 90% of MIB or geosmin in 1,000 gallons (3,785 liters) of clearwell or raw blend water, corresponding to a cost of less than US$0.35 per 1000 US gallons (3,785 liters).