ELECTROCHEMICAL TREATMENT OF LANDFILL LEACHATE - OXIDATION AT TI PBO2AND TI/SNO2 ANODES/

Leachate originating in landfills where municipal solid wastes are dis posed is a wastewater with a complex composition that could have a hig h environmental impact. The primary goal of this research was to inves tigate the feasibility of removing refractory organic pollutants and a mmonium nitrogen from landfill leachate by electrochemical oxidation. The effects of current density, pH, and chloride concentration on the removal of both chemical oxygen demand (COD) and ammonium nitrogen wer e investigated. Titanium coated with lead dioxide (PbO2) or tin dioxid e (SnO2) was used as the anode. An effective process was achieved in w hich the leachate was decolorized, COD was removed up to a value of 10 0 mg L-1, and ammonia was totally eliminated. Average current efficien cy of about 30% was measured for a decrease of COD from 1200 to 150 mg L-1, while efficiency of about 10% was measured for a near complete r emoval of ammonium nitrogen, starting from an initial value of 380 mg L-1. Results indicated that the organic load was removed by both direc t and indirect oxidation. Indirect oxidation by chlorine or hypochlori te originating from oxidation of chlorides is believed to be mainly re sponsible for the nitrogen removal.