Use of Biopolymer Entrapped Sulfate Reducing Bacteria and Metal Nanoparticles for Effective Aqueous Sulfate Removal

Abstract

Sulfate reducing bacteria (SRB) isolated from activated sludge were used to investigate sulfate removal from aqueous solution using calcium alginate entrapped SRB in batch studies with ethanol and lactose as the carbon sources. The interferences of pH, temperature, Al3+, Cu2+, and Zn2+ on sulfate removal were also investigated. Further, sulfate removal experiments were conducted with co-entrapped SRB and nanoscale zero-valent iron (NZVI) and separately entrapped SRB and NZVI. Results indicate that EntSRB can effectively remove sulfate from aqueous solution. 88-95% sulfate removal was achieved. Both ethanol and lactose worked well as carbon sources for entrapped bacteria. Interference studies indicated low sulfate removal in the presence of 25-50 mg/L of aluminum and zinc. Low pH (pH≤ 4) and low temperature (5°C) decreased sulfate reduction. NZVI appeared to have negative effects on SRB. Loading of 0.05 and 0.1 g of NZVI led to lower SO42- removal as compared to experiments without NZVI.