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Biofiltration Treatment for Iron- and Manganese-Rich Groundwater at Low On-Site Temperatures

Posted on 2017-10-24 in Events
Oct 27, 2017

There will be a grad student speaking this Friday Oct 27 at 3:30 pm in rm 155 Geology: Sandeep Dangeti, MSc candidate in Civil, Geological and Environmental Engineering:

Biofiltration Treatment for Iron- and Manganese-Rich Groundwater at Low On-Site Temperatures

Presenter: Sandeep Dangeti, Department of Civil, Geological, and Environmental Engineering

Supervisors:

  • 1. Dr. Wonjae Chang, Department of Civil, Geological, and Environmental Engineering
  • 2. Dr. Joyce McBeth, Department of Geological Sciences

Abstract:

Manganese (Mn), as Mn(II), often detected in Canadian groundwater and is an element of concern. Biofiltration technology is widely considered as a method to treat Mn(II)-rich groundwater. It is cost-effective technology. Manganese (Mn(II)) biofiltration under low temperature regimes (<15 °C) is challenging due to slow Mn(II) removal kinetics. Mn(II) oxidation by Mn-oxidizing bacteria (MnOB) and physico-chemical Mn(II) oxidation are the key mechanisms governing Mn(II) removal in these biofilters. The primary goal of this research is to improve our understanding of these mechanisms for Mn-oxidation in low-temperature Mn biofilters. A pilot-scale biofiltration unit treating low-temperature groundwater (4–8 °C) containing iron- (Fe(II); 2.81 mg/L) and Mn(II) (0.88 mg/L) was investigated. This biofiltration study demonstrated the onset, acclimation and acceleration of Mn removal. Mn removal reached steady-state functioning after 97 days, exhibiting 97±0.9% removal efficiency. After consecutive backwashes and filter inoculation with aged backwashed sludge, first-order rate constants (k values) remarkably accelerated; indicating the vertical progress of biofilter ripening. This study investigated the microbial communities in the steady-state functioning biofilters, and linked the microbial data to groundwater chemistry and characteristics of the field-aged biofilter media. Illumina MiSeq sequencing (16S rRNA gene) of the microbial communities in influent groundwater and biofilters revealed genus-level shifts in the bacterial community across the biofiltration unit, reflecting the functional enhancement of biological Fe(II) and Mn(II) oxidation. The surface morphologies on the aged filter media reflected both biological and physico-chemical Mn-oxide origins. X-ray absorption near-edge spectroscopy (XANES) coupled with electron paramagnetic resonance (EPR) revealed that biogenic birnessite was the dominant Mn oxide in the biofilters. This study reveals the biogenic formation of birnessite in a successfully operated biofilter, a reliable indication of microbially-mediated Mn(II) oxidation. This study indicated the feasibility of triggering rapid formation of biogenic Mn oxides using a cold-adapted MnOB consortium at 8 °C, and that Hydrogenophaga sp., can actively produce Mn(III/IV) oxides.

These research findings have important implications for improving biofiltration functionalization in cold regions, and represent a potential breakthrough for accelerating the onset and kinetics of Mn(II) oxidation in cold groundwater biofilters.

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