Landfill leachate production is an unavoidable by-product of landfilling solid waste. Mitigation of the adverse environmental impacts of landfill leachate is required at all active and closed landfill sites. Since leachate production continues long after the landfill is closed and no longer generating revenue, management strategies including low-cost passive and naturalized landfill leachate treatment systems are ideal. The past practice of dumping solid waste into unused tracts of land has created many brownfield sites with uncontrolled discharges of leachate to the receiving environment. Belle Park in Kingston, Ontario is an example of such a site that has been reclaimed for recreational use. A seep management strategy, which included the installation of leachate extraction wells, has been implemented at the site. Passive treatment systems, a coastal fringe wetland and a phreatophyte plots, were installed to evaluate their effectiveness in conjunction with the leachate seep management. Modelling estimated that originally, the pumping wells decreased leachate discharge by 60%, and with the newer wells in 2007 the discharge was decreased by 75- 85%. In situ pilot-scale evaluations of treatments systems are required to ensure adequate treatment of the leachate. The Merrick Landfill in North Bay, Ontario currently captures leachate produced on site and is assessing the potential of a hybrid-passive landfill leachate treatment system. This design process started with bench-scale design and assessment of active pretreatment options, followed by an evaluation of passive and semi-passive treatment systems at the bench-scale (treating 2-3 L/day) at both room (24oC) and cold (2oC) ambient temperatures. The design process culminated with a pilot-scale assessment of hybrid-passive treatment systems (treating 2000 L/d). Assessment of flow in passive treatment system is usually conducted with tracer evaluations. Vertical-flow passive treatment systems with intermittent dosing of leachate for passive aeration have both saturated and unsaturated flow regions. This research shows that tracer evaluation of these types of system was insufficient to measure the clogging within the pore spaces. Therefore a time-lagged flux method was created, based on the pilot-scale hybrid passive treatment system at the Merrick Landfill. This analytical solution quantified the changes in saturated hydraulic conductivity in the treatment system cells. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2011-09-30 15:55:45.73

The Williams Brothers Mine is located in Mariposa County, California. Surface waters from the site drain into the south fork of the Merced River and the San Joaquin River Basin. The mine was developed in the 1980s and mined intermittently until 1996. In 1998, concerns of acidic drainage at the site arose. Effluent sampling by Engineering Remediation Resources Group (ERRG) found acid mine drainage (AMD) characterized by a pH of 3.9, sulphate concentrations of 100 mg/L and low metal concentrations of 0.074, 4.60, 1.23, 0.047 and 0.133 mg/L for Cu, Fe, Mn, Ni and Zn, respectively. The aim of this research was to evaluate passive treatment system alternatives for the mitigation of the AMD to meet water quality objectives for the San Joaquin River Basin. A bench-scale study was undertaken which consisted of 3 systems treating synthetic AMD: (1) a peat biofilter to remove dissolved metals followed by an anoxic limestone drain (ALD) to increase alkalinity and pH; (2) a sulfate reducing bacteria (SRB) bioreactor followed by an ALD, in which SRB reduce sulphate to sulfides, generating alkalinity and decreasing metal concentrations via metal sulfide precipitation; and (3) a SRB bioreactor. Synthetic AMD was produced to represent AMD characteristics observed at the site. The peat-ALD system effluent pH was 6.9 and concentrations of Fe and Cu decreased to below water quality objectives with concentrations of 0.008 and 0.06, respectively. The SRB-ALD and SRB system effluents met water quality objectives for pH and Cu, Ni and Zn metal concentrations. The effluent pH for both systems was 6.5. The SRB-ALD system reduced Cu, Ni and Zn to concentrations of 0.004, 0.016 and 0.025 mg/L, respectively. The SRB system reduced metal concentrations for Cu, Ni and Zn 0.006, 0.010 and 0.027 mg/L, respectively. Based on the bench-scale study, the pilot-scale system consisted of a combined passive treatment system containing a peat biofilter, SRB bioreactor and a limestone drain. Pilot-scale testing commenced on May 23rd, 2007. To date, some metal attenuation has been observed, with average effluent concentrations of Cu, Fe, Mn, Ni and Zn equal to <0.005, 0.92, 0.45, <0.005 and 0.049 mg/L, respectively. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2008-01-29 12:42:03.58

Bellvue Mine is an abandoned coal mine on the West Coast of the South Island which discharges severe acid mine drainage (AMD) into the nearby Cannel Creek. This site is unique in that iron is in a ferrous or reduced form at the mouth of the mine, but due to the slope of the site, the AMD becomes aerated and subsequently the iron oxidises into ferric form as it moves downstream. Research was conducted to examine the geochemistry of the AMD at the site and investigate the performance of selected passive treatment systems at this site, with a view to informing decisions for passive treatment at other comparable mines on the West Coast. A range of small-scale trial passive remediation systems were installed, including an anoxic limestone drain (ALD), a bioreactor, and two mussel shell reactors. Results from the trials showed that the mussel shell reactor treating oxidised water was the most effective at reducing the concentration of dissolved metals in the AMD. A range of factors including hydraulic residence time, geochemistry of the Bellvue Mine discharge, and unexpected equipment issues all contributed to the results of the trials, and are important factors that need to be taken into consideration when designing a full-scale system for this site and others.

Research is presented that evaluates a semi-passive treatment system for remediation of contaminated groundwater with elevated dissolved metal concentrations, including selenium and sulphate, at the Wolverine Mine, Yukon. Laboratory up-flow columns were used to treat simulated mine impacted waters. Five columns were filled with varying compositions of gravel and creek substrate organics, and were un-amended or amended with manure, sewage sludge, zero-valent iron, or wood chips and alfalfa. Selenium, sulphate and other parameters of concern were lowered in column effluents, most effectively by the control column and by the columns amended with sewage sludge. Column effluent metal and sulphate concentrations provided evidence that co-precipitation, adsorption and microbially mediated redox reactions were the predominant biogeochemical mechanisms operating within the columns. Based on this research, recommendations are made to further the design of a semi-passive treatment system that may be installed at the mine site upon closure.

This research was completed to assess passive treatment methods for mitigation of acid mine drainage (AMD) at a former mine site in British Columbia. The objectives were to determine if suitable passive treatment methods were available, and if concentrations of Cd, Zn, and other key contaminants in groundwater could be reduced to below regulatory standards during bench-scale testing. Biological treatment with sulphate reducing bacteria (SRB) was selected, and bench-scale treatment testing was conducted using columns amended with low cost organic sources. Removal of more than 99% Cd, 93% Co, 96 % Cu, 86% Ni and 98% Zn was observed, resulting in metals concentrations in treated effluent consistently lower than applicable groundwater standards. Sustainability attributes of treatment with SRB and the potential to recover valuable metals are discussed, and recommendations for further testing and implementation are provided.

Successive Alkalinity-Producing Systems (SAPS) have proven to be a viable alternative to chemical treatment for renovating acidic mine drainage (AMD). The lack of water quality based design guidelines, however, is believed to be a cause of the variability of SAPS performance in the field. This study monitored eight SAPS systems for the purpose of determining the effect of influent water quality and system design on system performance. Monthly water quality data were obtained for each system over periods ranging from 3 to 5 years. All systems demonstrated an ability to generate alkalinity and/or neutralize acidity. These systems revealed significant correlations between net alkalinity production and log residence time (r = 0.7414), influent total iron (r = 0.7357), and influent non-manganese acidity (r = 0.6919). From these relationships, a calibrated model was developed for predicting SAPS net alkalinity generation. As a compliment to the field study, a series of laboratory-scale SAPS columns were studied for a period of 12 months to examine the effect of residence time on system performance and to monitor the internal changes in water quality. The columns were operated at residence times of 17, 30, 60 hours with three replicates each and were subject to ambient temperature fluctuations. Data revealed that systems with residence times below 25 hours in the organic layer were unable to adequately reduce dissolved oxygen concentrations in the organic layer to prevent limestone armoring. The results of this study suggest water quality based guidelines for designing SAPS systems. / Master of Science

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