Decomposition of Solid Waste in Test Lysimeters

Eight test lysimeters containing 100-200 tons of refuse each were monitored for seven years for leachate and runoff rates, leachate and gas composition, refuse temperature, and surface settlement. The lysimeters were designed to indicate the effects of refuse shredding soil cover, and lift thickness on the monitored parameters. More runoff but less evapotranspiration was obtained with soil cover, with the result that leachate rates were approximately the same with or without soil cover. Shredded refuse produced higher peak concentrations of matter in leachate than unprocessed refuse when landfilled under similar conditions. The absence of soil cover resulted in leachate strengths declining rapidly after peak concentrations were produced, with the result that shredded refuse without cover produced less COD than either shredded or unprocessed refuse which was covered. Doubling the depth approximately doubled the leachate COD levels, but greatly increased the stabilization time required to low COD levels to be attained. Placing a second lift of refuse over a relatively stabilized first lift resulted in 75 to 99% reduction in COD produced by the second lift.