Effective Separation of Vermicasts fromEarthworms Using a Cylindrical Rotary Trommel Separator

Abstract

Vermicomposting technology is widely being used worldwide as a solid waste management strategy. During vermicomposting Eisenia fetida earthworms ingest the solid organic waste and after a bioconversion process it is expelled as vermicasts. These vermicasts can be used as solid bio-fertilizers; however there are challenges of separating the earthworms from the vermicasts after vermicomposting. Pilot studies were therefore done using a cylindrical rotary trommel screen separator prototype to efficiently separate the earthworms from the vermicasts. The vermicasts were obtained from vermicomposting waste corn pulp mixed with cow dung manure and waste office paper. The cylindrical rotary screen had a mesh size of 4 mm, length of 250 mm and diameter of 90 mm. A throughput of 1.3 m3 /hr comprising of vermicasts and earthworms with a moisture content of 40-60% was separated trommel screen rotational speeds of 30-70rpm. The vermicasts separation efficient was around 80-95% but optimum separation of 95% was achieved at 40% moisture content and trommel screen rotational speed of 50rpm. Using a mechanical trommel screen separator increased the separation of vermicasts and earthworms, hence making the vermicomposting technology ideal.