Salinity and low temperature effects on the performance of column biochemical reactors for the treatment of acidic and neutral mine drainage. (March 2020)

• Record Type: Journal Article
• Authors: Ben Ali, Houssem E.; Neculita, Carmen M.; Molson, John W.; Maqsoud, Abdelkabir; Zagury, Gérald J.
• Is Part Of: Chemosphere. Volume 243(2020)
• Publication Date: 2020-03
• Subjects: Acid mine drainage -- Neutral mine drainage -- Column bioreactor -- Salinity -- Low temperature; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2019.125303
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Passive biochemical reactors (PBRs) represent a promising option for the treatment of mine drainage. In this study, the influence of temperature (22 and 5 °C), salinity (0 and 20 g/L) and hydraulic retention time (HRT) on the efficiency of PBRs for the treatment of acidic and neutral mine drainage (AMD and NMD) was evaluated. To do so, eight 11 L PBRs were set-up and operated with vertically upward flow. Synthetic AMD and NMD, with two salinities (0 and 20 g/L), were tested at ambient temperature (22 ± 0.5 °C) during the first 3 months, then at low temperature (5 ± 1 °C), for 5 additional months. The HRT tested was 0.5 and 1 day, for NMD, and 2.5 and 5 days, for AMD. Results showed a consistent efficiency, above 65%, with higher HRTs (1 vs. 0.5 day for NMD and 5 vs. 2.5 for AMD). At room temperature, metals and sulfate removal was better for non-saline synthetic effluents (>99% vs 95% for Cu, 99% vs >74% for Ni, 90% vs 75% for Fe, and <99% vs <96% for SO4 2− ), after 3 months. At 5 °C, removal efficiency decreased especially for Ni, from 99% to 74%, for both mine drainage qualities. However, sulfate removal was found to be better in saline AMD (<40% vs <10%). The simultaneous effect of low temperature and high salinity further decreased PBR performance. Although higher HRTs entailed better removal efficiency, hydraulic problems such as decreases in permeability of the reactive mixture may still lead to inhibition of long-term PBR efficiency. Highlights: Eight column PBRs were set-up and operated for 8 months in AMD and NMD treatment. Effects of salinity, temperature and HRT were thoroughly evaluated. High salinity and low temperature reduced PBR efficiency, especially for AMD. Longer HRTs (1-day for NMD and 5-days AMD) showed better PBRs efficiency. PBRs seem promising for AMD and NMD treatment in cold climate conditions.