Enhanced removal of micropollutants from groundwater, using pH modification coupled with photolysis

Direct ultraviolet (UV) photolysis coupled with modification of solution pH was explored as a method for the removal of organic micropollutants from groundwater. Photodegradation rates of most of the investigated compounds were pH dependent, however, its correlation with photodegradation rate varied among compounds. The potential of the pH modification during photolysis was determined for removal of a mixture of two pharmaceuticals sulfamethoxazole (SMX) and triclosan (TCS) in groundwater. The treatment included initial photolysis of the mixture at the optimal pH for TCS (i.e., 7.5-7.9), followed by pH modification to the optimal pH for SMX (i.e., 5), prior to a second irradiation period. The described procedure dramatically increased the removal efficiency (up to threefold) of the treated mixture compared to UV treatment at constant pH.