PHOTODEGRADATION OF NON-BIODEGRADABLE ORGANIC COMPOUNDS IN LANDFILL LEACHATE BY Mn-TiO2-BENTONITE

Abstract

The photocatalytic process helps to enhance biodegradability of landfill leachate. TiO2-bentonite nanocrystalline powders with various Mn-doping levels were synthesized by the sol–gel process using TiCl4 and manganese nitrate as precursors. The synthesized nanomaterials were characterized by X-ray diffraction analysis (XRD), Scanning electron microscopy (SEM) and Energy dispersive X-ray analysis (EDX). The experimental results indicated that the removal of chemical oxygen demand (COD), biological oxygen demand (BOD5), total organic carbon (TOC) and color by 2%Mn-TiO2-bentonite photocatalyst could be reached more than 81%, 83%, 65% and 96%, respectively. Under optimal conditions, the BOD5/COD ratio was elevated from 0.08 to 0.40. The organic compounds in landfill leachate before and after treatment using Mn-TiO2-bentonite photocatalyst were analyzed by means of high performance liquid chromatography (HPLC). The analysis result of HPLC diagrams revealed phenol, p-nitrophenol, p-crezol and some kinds of organic pollutants in the landfill leachate were totally decomposed after 12 h of treatment. Moreover, the re-usability of Mn-TiO2-bentonite catalysts was also studied with good efficiency. It was concluded that the Mn-TiO2-bentonite photocatalyst could be a cost-effective method for the pre-treatment of non-biodegradable organic pollutants in the landfill leachate.