March 23, 2007 | General

BioCycle World

BioCycle March 2007, Vol. 48, No. 3, p. 6

Ten secondary schools and colleges in Wiltshire, England, reports Growing Heap, are reducing waste disposal fees and running in-vessel composting machines while producing great compost. The $272,235 Schools Composting Technology Project run by the Wiltshire Wildlife Trust (and funded by a government agency) began in April 2005 to divert at least 40 metric tons of compostable waste each year.
The composting machines are the Rocket A500 from Accelerated Compost Ltd, based in Warrington, England and the T60 (Big Hanna) from Susteco in Sweden. The Rocket has a rotating blade in a stationary vessel, and leachate can be put back into the machine or into main drainage. The Big Hanna has a rotating barrel and no blade. Leachate is removed in the form of steam and vented through a pipe. It’s important to get the right mix of greens (high N waste) and browns (high C waste).
“Somebody needs to check the mix at least once a week to make sure the compost isn’t drying out, or staying too wet which can quickly lead to anaerobic conditions and the compost going sour,” says staff person Kate Robinson. Another person in charge of the Rocket says the machine needs one bucket of compostable waste a day. “It it’s overfed, the compost becomes wet and clings to the sides and top of the vessel instead of dropping down. It can become compacted, and then it has to be cleaned out.” Fine wood chips, sawdust or pellets work best as they absorb the water and mix well.
Big Hanna takes about three months to process waste and thus can take shredded cardboard and paper once the start-up period is over. The ratio is 1:10 pellets to food waste. Says a site supervisor who is responsible for running Big Hanna. “I put two liter buckets of kitchen waste into the machine everyday and then add the pellets. If I have 25 kgs of waste, I add 2.5 kgs of pellets. Afterwards, I can add wood chips, shredded paper and garden refuse. The whole process takes me 15 minutes. We’re getting good compost out of it for our flower beds with no problems at all.” In its first year, the ten schools diverted 30 metric tons of compostable waste from the landfill.
Growing Heap is published by the Community Composting Network, a national organization promoting composting in the community as the “most sustainable means of managing organic waste resources.” The website is:
A horse farm in Troy, New York is the

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