Vermicomposting of biodegradable wastes - effects of varying feedstocks and process conditions

An experimental investigation into the vermicomposting of biodegradable municipal waste was carried out using three different types of reactors. The initial trial was conducted using 45 small Type 1 reactors that were divided into three groups, which were maintained at different temperature conditions. The second trial was carried out to increase mass throughput and monitor reduction of leachate generation and process efficiency. Feedstocks employed during the first two trials were based on composition of biodegradable municipal waste, fresh biodegradable material, shredded newspaper and green waste. However, the third trial was conducted using two identical Type 3 reactor beds, which were fed with re-hydrated mature green waste compost (60 ± 2 %, m/m moisture content). Measurements of temperature, pH, redox potential, mass throughput, mass reductions and earthworm biomass are presented and discussed. The mass feedrate for reactors Type 1 and 2 comprising fresh biodegradable and newspaper was approximately 5 kg m-2 week-1 and the corresponding mass reduction was 86 %. Only one the reactors containing fresh biodegradable and newspaper feedstock sustained earthworm biomass and showed the highest (35 %, m/m) volatile solid content reduction. For the Type 3 reactor using mature green waste compost showed only a 22 % mass reduction, while both earthworm biomass and number were substantially reduced.