Recovery and reuse of spent chrome tanning effluent from tannery using electro-oxidation technique

Abstract

Leather manufacturing is one of the industrial activities, contribute significantly to economy and employment. Chromium being a carcinogen, the discharge of chrome tanning wastewater is associated with serious health hazards and significant negative environmental impacts. The present research deals with the recovery and reuse of chrome tanning effluent by mineralizing the organic contaminants present in the chrome tanning wastewater through electro-oxidation technique. The EO process was carried out by using titanium as anode for 120 min with variation in current density (3.0 V; 12 A and 4.0 V; 15 A). COD and TOC were found to decrease gradually with respect to time. The treated chrome liquor was then subjected to the reduction reaction using sodium metabisulfite so as to reduce the hexavalent chromium, to trivalent state. The leather produced using the recovered chrome liquor along with fresh chrome tanning agent was found to have good hydrothermal stability and adequate chromium content. This method of treating tanning effluent is an economically viable and environment-friendly alternative method for avoiding the disposal of chrome effluent.