Leaching From Land Disposed Municipal Composts: 1. Organic Matter

Abstract

Based on visions of using municipal compost (refuse-sludge mixture) to reclaim stripped land such as abandoned gravel pits in areas of significant groundwater resources, 17 lysimeters were monitored for a 2 1/2 year period with respect to organic contents of leachates. The lysimeters contained composts of varying origin, age (3 and 12 months), and packing depths (15-50 cm). COD concentrations of 2000-5000 mg O₂ 1^-1 were initially observed, but decreased after 2 years of leaching to approximately one-tenth. Only the packing depth seemed to affect the amount of organic matter leached within the first year. Large variations in composts quality may have masked other potential effects, e.g. compost age or maturity. The BOD₁₄ contents of the leachates were less than 10% of the COD contents and seemed to decrease as the leaching progressed. The organic matter of the leachates was not easily degradable, but was, on the other hand, not comparable to humic substances.