Removal of trichloromethane and trichloroethylene by suspended zero valent iron and ultraviolet irradiation.

Effects of stirring action (450 and 660 rpm) and UV irradiation (0, 8, 16 lamps) on TCM and TCE removal were studied in the presence of suspended iron powder (2 g L(-1)). Parameters such as residual fraction of TCM and TCE, ferrous ion buildup, aqueous oxygen remaining, and oxidation and reduction potential were determined as the reactions proceeded. Without TCM and TCE, the accumulation rates of ferrous ions, Fe0 corrosion product, at various UV intensities were in the order of 8 UV lamps > 16 UV lamps > without UV. With UV irradiation, its synergistic effect on TCE removal rate was much more pronounced than TCM. But TCM removal was affected by stirring action more than by UV irradiation. As TCM was present in the Fe0/UV system, its removal rate was in such an order as: 8 UV lamps > 16 UV lamps > without UV. With TCE, its removal rate was in such an order as: 16 UV lamps > 8 UV lamps > without UV. The presence of Fe0 retards the removal rates of both TCM and TCE, possibly due to Fe0 adsorption/desorption dominating Fe0 reduction reaction.