Agenda - Council - 10/14/1980 - Laserfiche WebLink

Home

- 13 - economics of sorting and removing contaminants from recyclable materials. A residential source separation program in Marblehead, Massachussetts, is currently recovering 25 percent of the solid waste stream (EPA, 1979). Similar well-run programs can bare the same results in the Twin Cities Metropolitan Area. The recovery rate in the Twin Cities with mandatory source separation could potentially reach 33 percent recovery, since Marblehead's pro- gram did not estimate commercial recovery of corrugated material or beverage containers, recovery of tires through recapping, tex- tile recovery, aluminum buy-back programs, and plastic recycling. Corrugated recovery in the Twin Cities during 1979 was at 70 per- cent of the potential supply, which amounts to seven percent of the total waste stream (John Walton, Champion International). Recovery rate results for the Marblehead program were as follows: newsprint corrugated ferrous aluminum 67.0 percent 6.6 percent 39.0 percent 0.3 percent clear glass green glass brown glass 61.0 percent 55.0 percent 39.0 percent Improving Marblehead's 25 percent total recovery rate into a 33 percent recovery rate is also feasible through improved residen- tial curb-side collection methods. For example, Boca Raton, Florida, recovers 82 percent of all generated newsprint (MPCA, unpub, data). Establishment of container deposit legislation can also improve upon the 25 percent recovery rate for the solid waste stream. Marblehead's program recovers 43.4 percent of all ferrous beverage containers (EPA, 1979). 5everage container deposits usually recover ferrous and nonferrous beverage containers at a rate of over 90 percent. Vermont's deposit law has achieved a 97 percent return rate (Vermont Agency of Environmental Conservation, 1977). C. WASTE PROCESSING Waste processing, for purposes of this report, is~defined as volume reduction techniques that are employed prior to landfilling, with or without materials recovery systems. 1. SHREDDING Shredding is a solid waste volume reduction technique that con- sists of milling the wastes~to reduce waste constituents to smaller, more uniformly sized particles. A shredding operation normally consists of a shredding unit, a transport network and the shredfill (landfill accepting shredded wastes). Several types of shredding devices are used, including vertical and horizontal axis hammer mills, vertical axis grinders and horizontal axis impactors. These shredders also usually include a variety of conveyors for waste routing scales, truck loading and unloading platforms and storage bins or areas. In the shredding process, solid wastes are milled to produce uniform particle sizes on the order of two to four inches in diameter. Waste size reduction results in up to 30 percent