Seasonal Effects of Domestic Wastewaters on the Cr (Vi) Reduction Potential of Bacillus Cereus S-6 and Ochrobactrum Intermedium CRT-1

Present study deals with the seasonal effects of domestic wastewater on the chromium reduction potential of strains Bacillus cereus S-6 and Ochrobactrum intermedium CrT-1. The presence of domestic wastewater from various localities caused a 20%—30% decrease in the Cr (VI) reduction potential of these bacteria. However, Cr (VI) reduction potential was 5%—20% higher in the presence of domestic wastewater collected in the summer season as compared to the winter season. The optimum temperature for reduction was observed at 37°C in case of B. cereus (96.9% Cr (VI) reduction) and 45°C in O. intermedium (96% Cr (VI) reduction). The pH preferences for optimum Cr (VI) reduction in these strains was pH 7 and pH 9 in case of B. cereus (93% Cr (VI) reduction) and O. intermedium (97% Cr (VI) reduction), respectively. The rate of Cr (VI) reduction was more in both strains when initially supplied with 100μg ml -1 of K 2 CrO 4 as compared to 500μg ml -1 and 1000μg ml -1 . In the presence of three domestic wastewater samples, the rate of Cr(VI) reduction was slightly less where the effluent was used in sterilised form.