Role of Wastewater Sludges in Stabilisation of Municipal Solid Waste Following Co-Disposal in Landfill

Abstract

The behaviour of sludge added to municipal solid wastes placed in a landfill has been investigated. Biochemical methane potential of different non-stabilised sludges was measured and ranged between 135 and 287 l kg−1 VS added. The kinetics of methane production of an activated sludge at different moisture levels from 55 to 99% were compared. An important influence on the stabilisation rate of activated sludge was shown between 75 to 90%. The leachate organics, nitrogenous and phophorus load released by the dewatered activated sludge were quantified. Then the long-term anaerobic storage of municipal solid wastes alone and mixed with two types of sludge was studied in five pilot scale reactors. The addition of 10% of sludge in municipal solid wastes was shown, during the following three months of incubation, to increase up to 13 times the leachate volume, depending on the moisture of the sludge. The concentrations of organic matter and ammonia were also largely increased. The degree of mixing, the moisture and also the lime content of the sludge were shown to be crucial parameters for predicting the behaviour of the sludge in a co-disposal landfill. Activated sludge with no lime treatment, anaerobically as well as aerobically developed, proved to be a potential inoculum for municipal solid wastes stabilisation, improving the start of methane production.