I Page 16 RAIN April1979 t, Turning a "waste" into a resource is the same kind of attitudinal change that allows us to turn a tragic experience into a positive learning and sharing experience. It's looking at something old in a very different way than we're accustomed to. Sewage sludge, commonly considered "waste" and resultantIy dumped into the ocean, is currently being looked at by many U.S. cities as a valuable resource. Composting of wastewater treatment sludge rather than incinerating, landfilling, trenching, or ocean dumping (the latter which must cease by 1981 per the U.S. EPA) creates a cost-effective alternative to sludge disposal that produces a marketable end product, and completes a circular flow of organic matter, replenishing depleted soils. Composting sludge with locally available bulking materials, including paper waste products, wood chips, cotton gin trash, peanut hulls, leaves, suga~cane bagasse, straw, corn cobs, etc., is currently in operation in at least seven U.S. municipalities and cities from Los Angeles, California to Bangor, Maine. The use of the end product as a low analysis fertilizer and soil conditioner has applications from re-vitalizing stripmined land to urban landscaping and from use on agricultural crops to ornamental plants. It is more cost effective than landfilling, trenching and incineration, and more readily usable by the soil in a composted form. It is economically viable only on a regional basis because composting involves bulk volumes that can be transported only limited distances; so community composting presents a de-centralized alternative that completes a cycle within a region. This appropriate technology that is more labor and land intensive than capital intensive is now being seriously undertaken by many cities. Increasing regional self-reliance and recycling volumes of organic "wastes" which are highly concentrated in urban areas is a sensible way of utilizing resources that have too long been disregarded and substituted for by economically and energy expensive petrochemicals. The process now in use most commonly and successfully (the Beltsville Pile method) works simply as follows: Raw or digested sludge from a wastewater treatment plant, which is preferably adjacent to the composting facility, is mixed with wood chips as a bulking (aerating) material in a stationary pile that has perforated pipe and air blown through it (see illustration). The process is land-intensive, so as well as an extended pile variation which halves the space needed, innovative and inventive uses of land, such as composting on an unused airport runw.ay as in Bangor, Maine, are possible. This process creates temperature high enough to effectively destroy human pathogens, creates a stable end product, and eliminates malodors associated with other sludge treatment methods. The rich composted soil that is created on the same principle as a backyard composting pile takes from 3 to 6 weeks to metamorphose from sludge into compost. The problem of the residue of heavy metals from urban wastewater in sludge, which could be transmitted to humans via plant absorption, has been studied since at least 1971. This problem can occur only in particular urban areas where industrial wastes that are not pretreated are discharged into the wastewater. The heavy metal content varies with the method Cities,Sludge,Soil.and Sense Compost Science/Land Utilization, Journal of Waste Recycling, bi-monthly, edited by Jerry Goldstein; US/year, 6 issues, from : The JG Press Box 351 Emmaus, PA 18049 215/967-4010 This fipe periodical is the best place to go for the state of the art in composting. The Jan.!Feb. 1979 issue has "an overview of composting in various municipalities across the country. An in-depth discussion of the principles for evaluating and selecting compost systems from reliability and economics, energy and labor to the state of the art in closed and window systems appeared in the May/June 1978 issue. These provide an excellent resource for the community wishing to explore this option. "Directory of Composting Systems," a li!;t of American and European firms which manufacture composting and/or hredding equipment, appears in Compost Science/Land Utilization, Jan.! Feb. 1979 issue also. Here's where to t:ut in checking out equipment. Single issues are available for $2.50 each. 1979 Composting and Waste Recycling Conference, May 2-4, 1979, in Philadelphia, PA. $95.00 includes field trips to operating sites and land applications, luncheons and proceedings. Contact: Mildred Lalik Compost Science -at the above addresss No doubt this is an excellent opportunity to obtain the most current information about municipal composting from those who have direct experience with this process. Sewage Sludge Composting in Small Towns, by G. M. Leighton, R. D. Harter and G. R. Crombie, 1978, 18 " pp., from: . NH Ag. Experimental Station U. of New Hampshire Durham, NH 03824 or George Crombie (above address) Since 1975 the City of Durham has been using a sewage sludge compost- I. ing system. This report describes that· system, the costs of operation, levels of heavy metal concentration. Another good look at the work and learnings of an operative system. by Linda Sawaya Composting Sludge for Land Application, by J- F. Parr, E. Epstein and G. B. Willson, 15 pp., 1978, from: U. S. Ag Research Center, Beltsville address above A concise overview of the Beltsville Method, including history, chemical composition of sludge befure and after composting. Costs ofSludge C01!'posting, ARSNE-79, Feb. 1977, 18 pp., from: U.S.D.A. Agricultural Research Service Comparative costs uf composting with other sludge disposal processes. Gives a little history as well as operative information. Composting Sewage Sludge by HighRate Suction Aeration Techniques, Dale Mosher and R. Kent Anderson, 1977,50 pp., from: U.S. EPA (address above) This interim report describes work performed in the Bangor, Maine, composting system in two parts: the operation at Bangor and Pointers for Other Municipalities. An important perspective- learning from the experi ence of others.
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