Vermicomposting: Industrial scale vermicomposting of pulp and paper mill solids with municipal biosolids and DAF sludge from dairy industries

Abstract

The Carter Holt Harvey Kinleith pulp and paper mill has undertaken huge efforts to minimise its landfilled organic wastes over the last decade. Besides increasing fibre recovery rates options for alternative uses of pulpmill solids have been evaluated over time. In 2008 a feasibility study of industrial scale vermicomposting of Kinleith pulpmill solids was been initiated. After proofing of concept, Noke Ltd. started operating its industrial wormfarm at full scale, vermicomposting all primary solids from Kinleith mill. In 2010 trials of mixing the secondary biological solids from the oxidation ponds with the primary solids were successful. Today 36,500 tonnes per year of mixed primary and secondary solids are diverted from landfill and are vermicomposted on the MyNOKE wormfarm. The pulpmill solids are converted to approximately 5000 m3 of organic certified vermicast. Vermicast is land applied to nurseries, kiwi fruit orchards, maize paddocks, pasture, and for erosion control. From 2013 dewatered sludge, here called 'recycled paper solids' from Carter Holt Harvey's recycling paper plants will be combined with other fibrous mill wastes, municipal biosolids, and with dissolved air flotation (DAF) sludge from milk processing plants for vermicomposting.