Photocatalytic Degradation Of Cholorinated Organic Compounds In Industrial Waste Water

Abstract

Wastewater streams are posing a serious threat to human life, plants and newlineanimals and also to ecosystems of receiving water bodies. One of the main causes of newlinesurface water and ground water contamination is industrial discharge from textile, newlinepulp and paper, pharmaceutical and other chemical industries. Wastewater treatment newlineis based upon various physical, chemical and biological processes. In fact, it is a combination of many operations like filtration or flocculation, sterilization or newlinechemical oxidation of organic pollutants. After filtration and elimination of particles in suspension, the conventional treatment technologies like air stripping, carbon adsorption, and biological treatment can be used. But they have limitations, for newlineexample, stripping and adsorption merely transfer contaminants from one medium to another whereas biological treatment process cannot remove all types of newlinecontaminants, especially the organic pollutants that are bio-recalcitrant in nature. newlineThe industry that manufactures bleached chemical pulp consumes considerable quantities of chlorine and discharge large quantities of chlorinated organic matter into rivers, lakes and oceans. Pulp and paper industry generates about 80-180 m3 of wastewater per ton of paper produced. Of the different wastewaters newlinegenerated by the pulp and paper industry, bleach plant effluents are considered to be the most polluting. In the bleaching process, the lignin gets converted to chlorolignins, which further decompose into chlorinated phenolics, and dioxins, which are toxic, non-biodegradable and have tendency to contaminate food chains through bioaccumulation phenomenon. The chlorinated organic compounds in the bleach plant effluents mainly consist of chlorophenols, chlorocatechols, chloroguaicols, chlorovannilins and chloroacetones etc. Since chlorolignins are not easily biodegradable, biological wastewater treatment method is not effective in treating these bio-recalcitrant compounds. newline