Selenate bioreduction using methane as the electron donor in a biotrickling filter

114This study investigated anaerobic bioreduction of selenate to elemental selenium by marine lake sediment from Lake Grevelingen in the presence of methane as a sole electron donor in both batch and continuous studies. Complete bioreduction of 14.3 mg.L⁻¹ selenate was achieved in batch studies, while up to 140 mg.L⁻¹ selenate was reduced in the biotrickling filter with a continuous supply of 100% methane gas (in excess) at a reduction rate of 4.12 mg.L⁻¹ d⁻¹. Red coloured deposits, characteristic of Se(0) particles were observed inside the polyurethane foam packing in the biotrickling filter, which were further confirmed using graphite furnace atomic absorption spectrophotometer. The biotrickling filter was operational for 348 days and > 97% selenate reduction was observed for the entire time required for complete bioreduction of selenate decreased gradually with each step feed of selenate.