Pollution Research Paper

BIODEGRADATION OF TANNERY EFFLUENT HEXAVALENT CHROMIUM BY ASPERGILLUS NIGER USING EGG SHELL PACKED BED REACTOR

R. MAGESH, R. DHANASEKAR, K. JAYAPRAKASH AND K. SIVAKUMAR

Abstract

Tannery effluent is well known for the contamination of toxic hexavalent chromium VI. Although many chemical and physical treatments are suggested, there is no a well proved treatment technique for the complete degradation of chromium salts. There is a scope for the application of biotechnological methods for the treatment of the tannery effluent. The present study involves identification and culture of a biodegradative tropical potential fungus Aspergillus niger as a bio agent for the biotransformation. The results have exhibited that the inoculum of said fungi in effluent media has significantly reduced the chromium level (7.1 mg/L to 4.3 mg/L). In order to increase the contact time of the microbe for the degradation a packed bed reactor is designed. The glass column of the reactor is filled with egg shell powder to achieve a constant steady flow of the effluent into the reactor to get more time for the reaction of microbe and the effluent. The influencing variable factors such as flow rate of the effluent and the height of packing bed are correlated with the rate of reduction. At the flow rate of 3lt/hr the reduction was significant (7.5 mg/ l to 0.52 mg/L). Likewise at the bed height of 100 cm the reduction was pronounced well (7.5 mg/ l to 0.5 mg/L). The above results are discussed with the design and establishment of technique for the tannery effluent treatment plant of industrial application.