Compost based biocap performance

Gas diffusion coefficient (transport parameter) and maximum methane oxidation capacity or Vmax (reaction parameter) in compost based media were studied.; A new equation to predict the diffusion coefficient in compost based media was proposed. The advantage of this model is that it can predict the air porosity at which diffusion coefficient ceases.; The dependency of Vmax on moisture content, temperature, and organic content (due to the presence of compost) were investigated. The results showed a maximum Vmax of 45.3 mu mol/g dw.h in compost at 92.6% moisture content and at temperature close to 30°C. Both moisture content and temperature were found equally important, and the effect of one parameter was found significant when the other parameter approaches optimum value. Using experimental values, a design curve was developed using four important parameters; temperature, moisture content, organic content, and Vmax. This curve is expected to predict one of the parameters if the other three parameters are given.; Compost columns were found to oxidize methane at a rate of 417 g/m 2/d compared to 166 g/m2/d in the soil column. The depth of the maximum methane oxidation zone was found varying with the type of the material, surface condition, moisture content and gas flux rates, and could ranges from 5 to more than 50 cm depth. The maximum methane oxidizing capacity of the 70/30 field biocover could not be investigated because of the low methane emission rate from the test cell, but was still found to eliminate a methane flux in excess of 4 g/m2/d.; In practice, the biocover made of low compost fraction (<30%) could be a suitable option as high compost biocovers demand for higher moisture content compared to low compost biocovers. Reduction in compost fraction also reduces the respiration rate which could off-set methane oxidation by consuming part of the available oxygen.; A significant difference was found in methane oxidation rate between column experimental results and simulated using incubation experiments. Using both results a correction curve is proposed, which could effectively used to simulate methane oxidation rates in columns and field settings.