Author(s)

M. Quintern

Abstract

More than 180,000 tonnes of carbon rich fibrous by-products from New Zealand’s largest pulp and paper mills have been disposed to landfills for decades. The aim of this project was to identify a sustainable source of nutrient as well as a cost effective technology to produce a high quality soil conditioner or fertiliser. Blending pulpmill solids with nutrient rich municipal biosolids (sewage sludge) was considered highly suitable for vermicomposting. The project, which commenced in 2007, proved the efficacy of the sludge through both laboratory and field trials. The design of a full industrial scale vermicomposting process had been developed and evaluated at a pilot scale of 2,000 tonnes blended wastes. We are operating as a full scale commercial business processing 150,000 tonnes of organic waste per year via compost worms. Through this we have supported two pulp and paper mills to attain organic waste free status. Furthermore biosolids from three communities with a total of 220,000 people are processed on 50 hectares of vermicomposting worm farms. The target for 2015 is that the remaining pulp mill will also attain an organic waste free status along with further communities comprising of some 120,000 people sending their biosolids to the vermicomposting operations taking the total product to some 230,000 tonnes per year. More than 20,000 tonnes of high quality vermicast is currently produced, which complies with the qualification criteria of an AA-grade product, as determined by the New Zealand biosolids guideline. The final vermicast is applied to more than 1,000 ha of farmland, orchards, nurseries and golf courses with growing demand. Keywords: vermicomposting, vermicast, pulpmill solids, biosolids, sewage sludge, land utilisation.

Keywords

vermicomposting, vermicast, pulpmill solids, biosolids, sewagesludge, land utilisation.