Enhanced biological removal of Cr(VI) in Continuous Stirred Tank Reactor (CSTR) using Aspergillus sp.

Abstract

Abstract. Biological removal of Cr(VI) from aqueous solution was studied in batch and continuous mode of operation using the growing Aspergillus sp. Continuous removal of Cr(VI) was studied in Continuous Stirred Tank Reactor (CSTR) maintaining the microorganism in living or biologically active state. In batch bioreactor, the growth and Cr(VI) removal by the organism were studied at different initial Cr(VI) concentration at pH 5.0. Whereas, in continuous mode of operation both single and two stage reactors were also studied for Cr(VI) removal. Batch studies indicated the maximum specific Cr(VI) removal to be 41.2 mg.g -¹ at pH 5.0 and at 500 mg L -¹ initial Cr(VI) concentration. However, in continuous mode of operation, the maximum specific Cr(VI) removal was found to be 39.4 mg.g -¹ after first stage operation with an additional 39.32 mg.g -¹ obtained in the second stage operation. Hence, these results indicated that the continuous mode of operation could be the ideal operational strategy in which the process could be operated for longer duration with a enhanced Cr(VI) removal.