2015 CSCE Annual Conference Regina - Building on our Growth Opportunities Conference
Dr. Babak Roshani, Delco Water Division, Delco Automation Inc.
Dr. Joyce McBeth, Canadian Light Source
Dr. Wonjae Chang, University of Saskatchewan
Iron (Fe) and manganese (Mn) are common elements of concern in groundwater in in the Canadian Prairies. Biological filtration that stimulates indigenous Fe- and Mn-oxidizing microorganisms that are naturally present in groundwater is often considered a cost-effective water treatment option. One of challenging aspects of biological treatment is that low temperatures significantly hinder microbial metabolic activity. This study focuses on enhancing cold-adapted, indigenous microbial populations for Fe and Mn oxidation at the in situ low temperature (8 °C) of a pilot-scale biofilter at the Langham water treatment plant in Saskatoon. The pilot-scale biofiltration system consists of two aerated biofilters connected in series, designed to remove Fe in Filter 1 and Mn in Filter 2. The growth of biofilms was promoted either on conventional plastic filter media or on anthracite. Rapid oxidization of iron occurred through both filters in one month (99% removal, p-value <0.05). After several months, Mn removal was successfully achieved in Filter 2 when it contained anthracite (97% removal, p-value <0.05). Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDS) and Inductively Coupled Plasma (ICP) analyses confirmed the removals of Fe and Mn below the water quality criteria. The increase in Oxidization Reduction Potential (ORP) in Filter 2 strongly correlated to the decrease in Mn concentrations in the aqueous phase. Adsorption of Mn on anthracite, which was confirmed by an additional batch experiment, likely contributed to the biological removal and/or bacterial immobilization of Mn in Filter 2. Culture-dependent microbial assessments coupled with the Leucoberbelin method indicated the presence of Mn-oxidizing bacteria in the biofiltration system.