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A mathematical model was developed to simulate methane and carbon dioxide production from simulated landfill column reactors operated under sulfate reducing and methane producing conditions. The model incorporated governing equations which describe the chemical and biochemical processes responsible for the degradation of organic waste materials. These processes were hydrolysis, acidogenesis, methanogenesis and sulfidogenesis. The differential equations were numerically solved using Stella Researcher Software. The model was calibrated and verified using 700 days of gas production data from the simulated landfill column reactors. The calibrated hydrolysis rate constants for newspaper and sludge were found to be higher in sulfate reducing reactors as compared to methane producing reactors. The simulated methane production was quite accurate in all the reactors, but the predicted carbon dioxide production in the sulfate reducing reactors was not so accurate for the first 100 days, which may be attributed to the necessity of further governing equations. According to the sensitivity analysis, hydrolysis rate constants and moisture factors were the two most sensitive parameters controlling the gas production.

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An enriched consortium obtained from lake-sediment was developed for the removal of heavy metals such as Cu, Pb, Cr, Ni, and Zn from heavy metal-contaminated water. The removal efficiency of heavy metals in a shaking condition was generally higher than that in the static state. After the fifteenth enrichment with assorted heavy metals, the removal efficiencies in the shaking and static condition at an average concentration of 100 mg/L of each heavy metal were approximately 99 approximately 100% and 95 approximately 100%, respectively, depending on the type of heavy metal. An aerobically grown, pure culture isolated from an enriched culture was analyzed by 16S rRNA sequencing and identified as Ralstonia sp. HM-1. This strain was found to remove various heavy metals with an efficiency of approximately 97 approximately 100% at an average concentration of 200 mg/L of each heavy metal.

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