July 30, 2010 | General

Selecting A Slow Speed Shredder

short paper fiber and scalper wood wasteBioCycle July 2010, Vol. 51, No. 7, p. 24
This comprehensive evaluation reviews equipment capcable of grinding stumps and other land clearing debris to yield a larger particle size with fewer fines.
Craig Coker and Ken Newman

ROYAL Oak Farm is the largest permitted, multiple feedstock solid waste composting facility in Virginia, but it didn’t start out that way. Back in 1999, Ken and Barbara Newman, who purchased the farm in 1995 to raise chickens and hogs, began windrow composting the bedding and manure from the hog barns. This on-farm composting operation was done on crushed slag pads (slag is a residual from steel making) using a Backhus 16.55 windrow turner and a deck screen. Little bulking agent was needed back then as the hogs were dry bedded. The manure plus bedding offered a very compostable recipe.
In 2005, Royal Oak entered into a 10-year contract to handle residual short paper fiber (SPF) from a local paper mill. The Virginia Department of Environmental Quality (VA DEQ) required Royal Oak to repermit and upgrade the facility to meet Category IV waste-handling requirements. The permitting process took 18 months; the $2.2 million upgrade to the site took two years. The new permitted capacity is 150,000 tons/year of all compostable feedstocks except biosolids and municipal solid waste. The composting facility reopened in April 2008 with new asphalt pads, a lined storm water pond, and more than a mile of storm water recycling irrigation piping. The facility currently handles about 85,000 tons/year of paper mill residuals, other industrial residuals, food processing sludges and both pre and postconsumer food wastes.
The SPF comes from a containerboard plant recycling old corrugated cardboard. The residual has a bulk density of 1,370 lbs/cubic yard, a moisture content of 75 percent, a nitrogen content of 1.4 percent and a carbon-to-nitrogen ratio of 40:1. Because the plant allows a small amount of sanitary wastewater to route to its onsite processing plant, it was decided in 2005 to pilot test various recipes of bulking agents to see how quickly temperatures would rise to the level prescribed by USEPA’s Process to Further Reduce Pathogens (PFRP, which, for windrow composting, is >131

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