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Sulfate, nitrate and selenium reduction in mining wastewater brine using anaerobic bacteria

University of British Columbia

The mining industry is a water usage intensive industry that generates large volumes of wastewater. This wastewater is technically difficult to treat when it is very saline. Large quantities of reagents are needed for chemical treatment, which is very expensive. The current thesis explores the possibility of using anaerobic bacteria to treat highly saline wastewater, as an alternative and more cost effective technology. Specifically, the concentrations of sulfate, nitrate and selenium were monitored, as these are constituents of concern at many mine sites. Samples of brine at different stages of a reverse osmosis treatment process were received from a mining company. Growth media for anaerobic bacteria were made according to the concentrations of chemicals present in the bine samples with certain amendments. Three sediment samples collected from different mine environments were tested as inocula for the experiment. Three growth conditions were also designed in order to determine the best suitable treatment conditions: condition #1 contains additional ammonia and iron salt as nutrients, condition #2 has only additional iron salt as nutrient and condition #3 has only zero-valent iron as an alternative additional iron source. DNA samples were extracted from culture sediments and analyzed using qPCR. Based on the results obtained, it was found that different combinations of inocula and growth condition were suitable for removing the most amount of sulfate, nitrate or selenium separately. In order to remove all three constituents at the same time, the best treatment was using inoculum collected from Mount Polley and adding only iron (II) chloride salt as nutrient besides carbon sources (condition #2).

Text

2015-08-31

Attribution-NonCommercial-NoDerivs 2.5 Canada

http://hdl.handle.net/2429/54713

Chemical and Biological Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/2.5/ca/