TITANIUM DIOXIDE-MEDIATED PHOTOCATALYSIS OF A BIOREFRACTORY CHLOROETHER IN SECONDARY WASTE-WATER EFFLUENT

The effects of pH, soluble chemical oxygen demand (COD), suspended solids, and ammonia-nitrogen on the titanium dioxide (TiO2)-photocatalyzed treatment of 1,2-bis(2-chloroethoxy)ethane (BCEE) were investigated in secondary wastewater effluent. The photochemical oxidation of BCEE was pH dependent and most rapid at pH 4. Sequential increases in soluble COD were provided by the addition of filtered wastewater influent, and suspended solids were varied by adding sonicated mixed liquor. Photocatalysis rates were inversely proportional to soluble COD concentrations, and the reaction was completely quenched at a soluble COD of 164 mg l-1. Suspended solids in concentrations up to 90 mg l-1 and ammonia-nitrogen (0.83-70 mg l-1) did not affect the photochemical oxidation of BCEE. The results show that, of the water quality characteristics investigated, only soluble COD affected TiO2-mediated photocatalysis of the chloroether under the conditions of this study. Therefore, photocatalytic treatment of biorefractory compounds in complex matrices, such as wastewater effluents, may be possible if the concentrations of quenching species associated with the soluble COD are not significantly high.