Combined Treatment of Electrochemical and Ozonation for Dye Effluent

Abstract

This study evaluates the effectiveness of the combined electrochemical-ozone process on dye effluent from textile industries. Effluent from textile industries are contains huge amounts of dye & its constituents, mordant and sizing agents. Chromosphere group with conjugated double bond are responsible for colors in dyes which can be removed by breaking such bonds with help of molecular ozone or hydroxyl radical. Third or nascent O2 molecule in the O3 molecule is responsible for ozonation process. Molecular ozone is responsible for ozonation at lower pH and hydroxyl radical is responsible for ozonation at higher pH. This study was carried out by special fabricated bubble reactor. Ozonation or electrochemical process is operated simultaneously or intermittently to study and compare the operating time for ozonation and combined electrochemical-ozone process with respect to percent removal of color and TOC. In this experiment, ozone flowrate, current density and pH for both ozonation and combined treatment was varied. For electrochemical process in combined treatment aluminum electrode is taken for electrolysis. Present Study demonstrates effect of dye concentration of Reactive Red 120, Reactive Yellow 145 and applied current density, ozone flowrates and pH on decolonization and TOC reduction from dye effluent. The initial dye concentration is taken 500 and 1000 ppm and current density was maintained 0.556, 1.111 and 1.667 mA/cm2 and pH 2, 4, 6, 8, 10 and 12. As result shows from experiment, decolorization and TOC reduction is increases with increasing ozone flowrate, current density and pH. The TOC removal efficiency increases with increase in the initial concentration of dye solution. The ozone demand is increases with increase in the initial concentration of dye, ozone flowrate, current density and pH. The rate constant is increases with increasing ozone flowrate, current density and pH. The electricity cost of process using ozone vary from 1.7 to 1.9 Rs./lit and for combined process 0.68.to 1.66 Rs./lit at constant TOC reduction.