naa a22 4500 510752756 CHVBK 20180411083110.0 cr unu---uuuuu 180411e20131101xx s 000 0 eng 10.1007/s11270-013-1732-9 doi (NATIONALLICENCE)springer-10.1007/s11270-013-1732-9 Microbial Sulfate Reduction and Biogeochemistry of Arsenic and Chromium Oxyanions in Anaerobic Bioreactors [Elektronische Daten] [Ronald Cohen, Toshisuke Ozawa] A pilot-scale anaerobic bioreactor with high levels of microbial sulfate reduction, known to be capable of removing cationic metals from a metal- and acid-contaminated waste stream, was utilized to determine if the system would be effective in removing metals in the form of oxyanions such as arsenate and chromate. The system removed 90% to >99% of the arsenic and between 86% and 94% of the chromium from a waste stream containing 5mg/L of each. Cadmium, copper, iron, lead, and zinc also were removed. An equilibrium geochemistry computer modeling code, MINTEQAK, modified from MINTEQA2, was used for the chemical modeling of processes in the bioreactor. Experimental evidence on the chemical and biological reduction of arsenic and chromium and fluorescent diffraction analysis of precipitates support the following hypotheses: the primary removal process for chromium was the reduction of Cr(VI) to Cr(III) by sulfides, followed by precipitation of chromium hydroxide [Cr(OH)3(s)]; removal of arsenic was by direct microbial enzymatic reduction of As(V) to As(III) followed by precipitation of arsenic sulfides (As2S3 or AsS). Experimental evidence and modeling with MINTEQAK confirmed that 90% to 95% of the removal of arsenic and chromium occurred in the first quarter volume of the bioreactor. Additional removal of arsenic and chromium occurred in the remaining volume of the bioreactor. The use of a sulfate reduction-based anaerobic treatment system was effective for metal-laden wastewater with elevated concentrations of arsenic and chromium. Springer Science+Business Media Dordrecht, 2013 Microbial sulfate reduction nationallicence Arsenic nationallicence Chromium nationallicence Acid mine drainage nationallicence Acid rock drainage nationallicence Mining influenced waters nationallicence AMD nationallicence ARD nationallicence AMD treatment nationallicence ARD treatment nationallicence Cohen Ronald Division of Environmental Science and Engineering, Colorado School of Mines, Chauvenet Hall, 80401, Golden, CO, USA aut Ozawa Toshisuke Division of Environmental Science and Engineering, Colorado School of Mines, Chauvenet Hall, 80401, Golden, CO, USA aut Water, Air, & Soil Pollution Springer Netherlands 224/11(2013-11-01), 1-14 0049-6979 224:11<1 2013 224 11270 https://doi.org/10.1007/s11270-013-1732-9 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11270-013-1732-9 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Cohen Ronald Division of Environmental Science and Engineering, Colorado School of Mines, Chauvenet Hall, 80401, Golden, CO, USA aut NATIONALLICENCE 700 1- Ozawa Toshisuke Division of Environmental Science and Engineering, Colorado School of Mines, Chauvenet Hall, 80401, Golden, CO, USA aut NATIONALLICENCE 773 0- Water, Air, & Soil Pollution Springer Netherlands 224/11(2013-11-01), 1-14 0049-6979 224:11<1 2013 224 11270 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer