Moisture level and movement effects on methane production rates in landfill samples

Abstract Samples of refuse were obtained from selected landfills for the purpose of observing the rates of methane production under controlled moisture conditions. Samples of solid waste were obtained following the procedures reported by Hartz & Ham (1982) . The rates of methane production, for each sample, were observed under constant temperature conditions. The moisture levels for certain samples were then increased by adding water. The rates of methane production under the moisture modified conditions were then observed. When moisture levels were sufficient to produce leachate, the sample leachate was recirculated. A wide range of recirculation rates were examined. It was found that some methane production should occur with moisture levels as low as 10% (total weight basis). It was further found that incipient free moisture conditions (field capacity) occurred at approximately 40% moisture (total weight basis), and that when leachate recirculation was practised, methane generation rates were significantly higher when compared to quiescent conditions.