Reduction of Selenate from Simulated Wet Flue Gas Desulfurization Wastewater Using Photocatalyst and Microorganism

Abstract

The reduction of selenate [Se(VI)] from a simulated wet flue gas desulfurization (FGD) wastewater was attempted using photocatalyst and microorganisms. The photocatalyst reduction method consisted of TiO₂ and HCOOH as a photocatalyst and a hole scavenger, respectively. When a simple 0.5 mg/L Se(VI) solution was used, the photocatalytic reduction gave an efficient removal of Se(VI). In contrast, the photocatalytic reduction could not remove Se(VI) from the simulated FGD wastewater, due to the excess amount of co-existing SO₄^2- anion. Also, a biological reduction which used Se(VI)-reducing bacteria was investigated. When three kinds of bacteria (E. cancerogenus, P. stutzeri, and P. denitrificans) were used, Se(VI) in the simple 0.5 mg/L Se(VI) solution was effectively removed. However, for E. cancerogenus, the removal of Se(VI) was inhibited by the co-existing NO₃^- anion in the wastewater.