The Use of Algal Biomass to Sustain Sulfidogenic Bioreactors for Remediating Acidic Metal-Rich Waste Waters

Two different species of acidophilic micro-algae were grown in axenic culture, biomass harvested and injected into a low pH sulfate-reducing bioreactor, to act as a substrate for biosulfidogenesis. The hydrogen sulfide generated was used to precipitate copper in an off-line vessel, and the bioreactor pH was maintained by automated addition of a pH 2.5 feed liquor, to compensate for protons consumed by biosulfidogenesis. Results demonstrated the potential for using algal biomass for this purpose, precipitating about 1.5 mg Cu2+ L-1h-1, though rates of sulfidogenesis were considerably slower that when glycerol and yeast extract were used as organic feed-stocks.