Biological Treatment of Tannery Effluent in a Sulphidogenesis Cum Ammonia Removal Process (SCARP)

摘要

The major objective of present work was to develop a sulphiodogenesis cum ammonia removal process (SCARP) for simultaneous removal of BOD/COD, SO_4~(2-)/S~(2-) and ammonia from tannery effluent. The developed SCARP could treat efficiently the primary treated tannery effluent having influent concentrations of COD, SO_4~(2-) and NH_4~+ as 3900 mg/L, 3000 mg/L and 300 mg/L, respectively. The optimum Hydraulic Retention Time (HRT) of SCARP was found to be 10.5 hours. The COD, NH_4-N and SO_4~(2-) loading rates applied to SCARP at optimal HRT were 8.9 kg COD/m~3/d, 0.68 kg NH_4~+ /m~3/d, 6.84 kg SO_4~(2-)/m~3/d, respectively. The overall removal efficiency of COD, NH_4-N and SO_4~(2-) in the above loading rates was in the ranges of 90.8 - 94.8 %, 84 - 88.3 % and 64.2 - 70.2 %, respectively. The system could perform well in varying organic loading rates at different lower COD/SO_4~(2-) ratios expected in tannery effluent (0.5 to 3.0), where direct anaerobic treatment is not successful due to sulphide inhibition. There was no sulphide present in the final treated effluent. From the results obtained in this study, it is possible to conclude that SCARP has good potential as a cost effective appropriate treatment process to existing extended aeration process with nitrification and denitrification for the secondary treatment of tannery effluent.