Bio reduction of arsenate using a hydrog

Arsenate (As(V)) is a carcinogen and poses significant risks to groundwater quality worldwide. Traditional treatment strategies typically do not aim to convert As(V) into As(III), the latter being more toxic and mobile. This study explores the potential of a hydrogen-based membrane biofilm reactor (MBfR) as a means of reducing As(V) to As(III), thereby facilitating arsenic removal through precipitation or complexation techniques. The experiments were conducted by introducing As(V) into a denitrifying MBfR, which enabled its immediate reduction to As(III). Several short-term experimental trials were set up to assess the influence of varying As(V) and sulfate loadings, nitrate levels, and hydrogen pressure on the effectiveness of As(V) reduction. The results indicated that non-addition of sulfate led to the maximum As(V) removal percentages and flux. Importantly, it was found that while higher As(V) loading and lower nitrate levels facilitated enhanced reduction rates, increased hydrogen pressure did not further enhance As(V) reduction. Scanning electron microscopy and energy dispersive X-ray analysis confirmed that the resulting As(III) could be effectively precipitated with sulfide or adsorbed to Fe(II)-based solids.