Effect of COD/Sulphate Ratio on Anaerobic Digestion of Sulfate Rich Post Tanning Wastewater at Different F/M Ratios | Original Article

ABSTRACT:

Anaerobic digestion of post tanning wastewater was performed in batch anaerobic digesters for the influence of various parameters such as COD/Sulphate ratio (0.62, 0.67 and 1.19 (w/w) %) and F/M ratio (0.3, 0.5, 0.7, 0.9, 1.1, 1.3 and 1.5 (w/w) %). Among the studied conditions, F/M ratio of 0.3 was found to be optimum for the removal of COD and Sulfate from the post tanning wastewater. The maximum removal of COD was found to be 53.1, 64.8 & 80.1% and reduction of sulphate was observed to be 32.7, 46.9 & 58.1% at COD/sulphate ratios of 0.62, 0.67 and 1.19 respectively. The reduction efficiency of COD and Sulphate were decreased with increase in COD/sulfate ratios from 0.62 to 1.19 in anaerobic digester, a similar trend was observed for F/M ratio from 0.3 to 1.5% in anaerobic digestion. The production of methane gas at COD/sulphate ratio of 0.62, 0.67 and 1.19 were observed to be 189, 246 and 310 ml/g of COD removed. The maximum concentration of sulfide production was achieved for the sample which reached sulphate concentration of 426 mg/L at COD/sulfate ratio of 0.62, and the anaerobic digestion process was inhibited at this sulfide concentration. These results show that the post tanning wastewater with 0.62 COD/sulfate ratios shows process inhibition in AD.