Microcosms were prepared to test if added mineral Fe3+ and SO42- could treat landfill leachate and to examine intrinsic microbial/mineral interactions related to natural attenuation. Two oxidized native sediments were used from central Oklahoma. Three types of anoxic microcosms were prepared which included the addition of: (1) mineral ferrihydrite (Fe(OH)3); (2) mineral gypsum (CaSO4•2H2O); and (3) no mineral amendments. Each received a synthetic leachate consisting of 2000 mg/l non-purgable organic carbon (NPOC). Measurements of substrate consumption, dissolved ions, mineral utilization/precipitation, and biological gases were made over 12 weeks. The added CaSO42- and Fe(OH)3 were used as electron acceptors: CaSO42- by first order kinetics (k≅0.12 week-1) and Fe3+ by zero order kinetics (k≅0.16 mM week-1). The addition of either CaSO42- or Fe(OH)3 did not increase organic carbon degradation rates over methanogenesis, which was predominate in the non-amended microcosm set. Adding solid electron acceptors promoted carbonate and sulfide mineral formation and controlled greenhouse gases including CH4 and CO2. It is suggested that reduced Fe and S minerals could be used to assess organic contaminant degradation occurring due to Fe3+ and SO42- microbial reduction processes for natural attenuation studies.
All Science Journal Classification (ASJC) codes
- Environmental Science(all)