Identification of Sulfate and Arsenate R

This study investigates the role of anaerobic microbial communities in sheep manure as permeable reactive materials for the removal of arsenic (As) from groundwater via column tests. The experimental setup included a column packed with various materials, including zero valent iron (ZVI) and sterilized sheep manure, allowing the activation of sulfate-reducing bacteria. The findings demonstrated a significant decrease in sulfate concentration at a maximum rate of 0.6 mmol dm−3 day−1, with a corresponding increase in the δ34S isotopic ratio from influent to effluent, suggesting active sulfate-reducing processes. Furthermore, it was found that arsenate was immobilized more effectively on ZVI compared to arsenite. Bacterial community analysis, using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) on 16S rRNA sequences, identified several Clostridium species and Geobacter metallireducens GS-15 as dominant bacteria, irrespective of column height, with some species likely contributing to arsenic removal. These results indicate the potential of using sheep manure and microbial communities for effective arsenic remediation in groundwater systems.