Silage supports sulfate reduction in the treatment of metals- and sulfate-containing waste waters

• Published in: Water research (Oxford) Vol. 44; no. 17; pp. 4932 - 4939
• Main Authors: Wakeman, Kathryn D., Erving, Leena, Riekkola-Vanhanen, Marja L., Puhakka, Jaakko A.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Kidlington Elsevier Ltd 01.09.2010; Elsevier
• Subjects: Applied sciences; Bacteria; Bacteria - metabolism; Biodegradation, Environmental; Bioreactors - microbiology; Carbon; Chemical Precipitation; Denaturing Gradient Gel Electrophoresis; Electron donor; Exact sciences and technology; Fatty Acids, Volatile - analysis; Hydrogen-Ion Concentration; Iron; Metals - isolation & purification; Mining waste water; Other industrial wastes. Sewage sludge; Oxidation-Reduction; Passive treatment; Pollution; Polymerase Chain Reaction; Reduction; Silage; Silage - analysis; Solubility; Sulfate reduction; Sulfates; Sulfates - chemistry; Sulfates - isolation & purification; Sulfides - isolation & purification; Volatile fatty acids; Waste Disposal, Fluid; Waste treatment; Waste water; Wastes; Wastewater treatment; Water Purification - methods; Water treatment and pollution; Sulfate reduction; Passive treatment; Silage; Volatile fatty acids; Electron donor; Mining waste water; Sulfur compounds; Sulfate-reducing bacteria; Waste treatment; Iron II; Hydrogen sulfides; Volatile organic compound; Sulfates; Peat bog; Waste water; Industrial waste; Batchwise; Volatile fatty acid; Reactor; Semicontinuous; Organic compounds; Mining waste
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2010.07.025

Silage was used as source of carbon and electrons for enrichment of silage-degrading and sulfate reducing bacteria (SRB) from boreal, acidic, metals-containing peat-bog samples and to support their use in batch and semi-batch systems in treatment of synthetic waste water. Sulfidogenic silage utilization resulted in a rapid decrease in lactate concentrations; concentrations of acetate, butyrate and propionate increased concomitantly. Synthetic waste water consisting of Mn, Mg and Fe (II) ions inhibited sulfate reduction at concentrations of 6 g/l, 8 g/l and 1 g/l respectively. During treatment, Mn and Mg ions remained in solution while Fe ions partially precipitated. Up to 87 mg sulfate was reduced per gram of silage. Sulfate reduction rates of 34, 22 and 6 mg/l/day were obtained at temperatures of 30, 20 and 9 °C respectively. In semi-batch reactors operated at low pH, the iron precipitation capacity was controlled by sulfate reduction rates and by partial loss of hydrogen sulfide to the gas phase. Passive reactor systems should, therefore, be operated at neutral pH. Metals tolerant, silage-fermenting (predominantly species belonging to genus Clostridium) and sulfate reducing bacteria (including a species similar to the psychrotolerant Desulfovibrio arcticus) were obtained from the peat bog samples. This work demonstrates that silage supports sulfate reduction and can be used as a low cost carbon and electron source for SRB in treatment of metals-containing waste water.