CHROMIUM EXTRACTION FROM INDUSTRIAL WASTE WATER OF LEATHER-TANNING ETC.

Abstract

.The report deals with experimemental work to extract Cr3+ from industrial-water of leather –tanning industry in order to control the concentrations discharged to the environment . The extraction tests were carried out using raw bentonite and porcelanite as well as acid – activated materials . The waste – water treated was collected from main tanks as well as from Cr-tanning tanks . The results of this work showed that raw porcelanite is suitable to achieve total extraction of Cr3+ at about 6 ppm concentrations . It is also efficient in the extraction of Ni, K, in these waters as well as neutralization of the pH . However , the extraction tests on the water of the Cr- tanning ttttttnecessity of Cr- precipitation as solid material since the extraction efficiency of the bentonite and pocelanite is not enough to achieve total extraction at high Cr-concentrations(˃ 5000 ppm ) . The extraction capacity of the bentonite improved after asid –activation .lt was also noticed that extraction potential increases as the Cr3+ concentration increases , and decreases as the TDS concentration increases . The tests showed that it is possible to bring the Cr3+ concentration to the allowable environmental limit using raw porcelante in the main tanks . lt was also possible Cr3+ . Concentration from 5800 ppm to ˂1 ppm by precipitation , and to 0.3 ppm treatment with bentonite and porcelanite .