Comparative study of cellulose waste versus organic waste as substrate in a sulfate reducing bioreactor

The biodegradability and comparative effectiveness in treatment of acid mine drainage of ten locally available organic waste materials were examined. pH of AMD increased from 2.70 to 6.25, 7.10 and 7.50 with buffalo, cow and goat manures whereas cellulosic wastes increased the pH within the range of 4.83–5.32 in laboratory scale single substrate bioreactors. Significant reduction was observed in Eh, acidity and sulfate with manures in treated AMD. Maximum metal removal efficiency was 99.3%, 99.9%, 99.8%, 99.1%, 99.1%, and 73.8% for Fe, Cu, Zn, Ni, Co and Mn in maximum retention period of 10 days. The highest efficiency of metal removal was observed in bioreactors with manures as single substrate. The effectiveness of substrate depends on its biodegradation ability, the results with cellulosic waste indicates it may need more than 10 days to biodegrade. Biodegradability of organic waste was evaluated according to COD/SO42- and C/N ratio and the ratios of 0.48–0.57 and 22.22–23.00 respectively were adequate parameters for activity of sulfate reducing bacteria and pollutant removal efficiency.