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.
Highlights
Cr(VI) is one of the major toxic heavy metal pollutants in the environment (Sen et al, 2007) and is frequently present in wastewaters coming from industries such as electroplating, chrome plating, metal cleaning and processing, wood preservation and alloy preparation etc., (Germain and Patterson, 1974)
The lag period was found to be marginally increased upto 500 mg.L-1 initial Cr(VI) concentration, beyond which it increased significantly with increase in initial Cr(VI) concentration upto 1,000 mg.L-1. Both the growth rate (Figure 2) and the glucose utilization rate (Figure 3) by the Aspergillus sp. were found to be decreased with increase in initial Cr(VI) concentration ranging from 0-1,000 mg.L-1 glucose was found to be completely utilized in every case
About 95.5% decrease in biomass concentration has been reported with C. utilis as compared to only 4.5% decrease obtained in the present study conducted with Aspergillus sp. when Cr(VI) concentration was increased from 0 to 500 mg.L-1
Summary
Cr(VI) is one of the major toxic heavy metal pollutants in the environment (Sen et al, 2007) and is frequently present in wastewaters coming from industries such as electroplating, chrome plating, metal cleaning and processing, wood preservation and alloy preparation etc., (Germain and Patterson, 1974). It is a natural tendency for small and medium scale industries to discharge the wastewaters into natural environment without giving any prior treatment before disposal. The conventional treatment techniques used for removal of ISSN 2358-2731/BJBS-2018-0014/5/9/4/33.
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