Sulphate bioreduction for the treatment of polluted waters: solid versus liquid organic substrates

Abstract

BACKGROUND: In this study a comparison between two continuously operating fixed-bed column systems was performed in order to select the best operating conditions in terms of organic sources for sulphate reducing bacteria (SRB). The first column system (solid substrate, SS) was filled with a solid reactive mixture containing the organic matter necessary for SRB growth, while the second one (liquid substrate, LS) was filled with inert material and continuously fed by ethanol. RESULTS: In the SS column 50 +/- 10% sulphate abatement was reached at steady state, while metals were totally removed. Blank tests showed that biosorption was mainly responsible for both sulphate and metal removal. In the LS column, sulphate abatement was 70 +/- 10% at steady state against 10 +/- 5% of an identical column without inoculum (blank liquid substrate, BLS). Comparison with BLS showed that the main mechanism operating in this system was bioprecipitation. Estimated degradation rate constants for both SS and LS columns indicate similar performances (0.008 +/- 0.001 and 0.0085 +/- 0.0005 d(-1) for SS and LS, respectively). CONCLUSIONS: LS column systems offer a valid alternative to conventional SS systems, avoiding the use of potentially harmful wastes as organic sources for SRB metabolism. (C) 2009 Society of Chemical Industr

Minerals and Mine Drainage

“…Metal removal was found to be a function of pH, with the best removal occurring in a reactor operated at pH 5.5 and continuous sparging of hydrogen sulfide provided. Column reactors containing SRB and fed with ethanol were used to treat high sulfate wastes (Viggi et al 2009). Depending on conditions, sulfate reductions of 50% to 70% were achieved principally through bioprecipitation.…”