Photochemical Treatment of wastewaters

Abstract

In the present work, chemical/photochemical processes, specifically, Fenton and Fenton-like reactions were employed to treat a leachate from the municipal solid waste landfill of Astana (Kazakhstan). Each experiment lasted 120 minutes, and the treatment efficiency was assessed through total organic carbon (TOC), total inorganic carbon (TIC), total nitrogen (TN) and colour removal. An annular UV (254 nm) photoreactor operated in a batch recycle mode was used. The total volume of the solution was 250 mL, and the irradiated volume in the photoreactor was 56.8 mL. The effect of inorganic carbon, pH, initial H2O2 amount (0-9990 mg L-1), Fe(II) (200-600 ppm) and Fe(III) (300-700 ppm) concentrations on total carbon and colour removal was studied. The landfill leachate had initial carbon concentration equal to 5868 mg L-1 and pH 8.16. The total carbon was by 40-45% inorganic, and nitrogen was 90% inorganic in the ammonium form. Preliminary experiments showed that inorganic carbon acting as hydroxyl radicals scavenger inhibited significantly the photo-Fenton treatment. Without the pretreatment steps only 7.7% TC removal was observed, while 29% TC (equal to TOC) removal was achieved when the inorganic carbon was removed at the pretreatment steps.