Feasibility of vermistabilization for fresh pelletized dewatered sludge with earthworms Bimastus parvus.

The aim of this study was to investigate the feasibility of vermistabilization of fresh pelletized dewatered sludges (PDS) without any bulking materials using earthworms Bimastus parvus. For this, two pelletized treatments with 4.5mm and 14.5mm fresh PDS and one without pelletized treatment were setup. Earthworm's fate test showed that earthworms could not survive in the treatment without pelletisation. For two pelletized treatments, B. parvus had a good life, producing great numbers of cocoons and hatchlings, after 60days. Vermicomposting of PDS resulted in the decreases of DOC, ammonia-nitrogen and microbial biomass and activity while increases of electrical conductivity and nitrate-nitrogen and available phosphorous. These findings suggest the stable and beneficial vermicomposts were achieved. The overall results evidenced that the fresh PDS without blending could be directly stabilized by vermicomposting and the vermireactor containing 4.5mm PDS displayed a better performance than 14.5mm PDS.