Removal of Cr (VI) in Anoxic and Sulfate-Reducing SBRs

Microbial uptake of Cr(VI) at 3.2-10.4 mg/L dosing pattern in weekly sequential periods was investigated under anoxic and sulfate-reducing conditions in sequential batch reactors (SBR). Cr (VI)'s fate and acute effect was also determined on nitrate and organic matter (COD) reduction of unacclimated sludge cultures with methanol as substrate. Chromium (VI) was removed at an efficient level throughout the study with adaptation signs. Chromium's inhibitory effect was not observed on nitrate reduction which reached high levels following a three week adaptation period where organic matter reduction correlated to other mechanisms than nitrate reduction was altered. A higher yield of 0.88 and a chromium removal in relation to biomass was obtained in anoxic conditions. Organic matter usage was inhibited in both SBR where sulfate reduction was altered at the maximum dosing and accumulated in the reactor.