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PERSPECTIVE

CSU Winter, 2004, Vol. 12, No. 1, p. 3

Researchers On A 30-Year Compost Learning Curve

IN the early 1970s, James Parr - currently a member of the CS&U Editorial Board - was appointed chief of the USDA-ARS Biological Waste Management & Organic Resources Laboratory at Beltsville, Maryland. In a presentation at the BioCycle West Coast Conference 2004, Dr. Parr recalled how the U.S. Environmental Protection Agency decided to fund a major research program on sewage sludge composting to be conducted by USDA-ARS scientists. “We had some really 'top notch' chemists, engineers, microbiologists, plant scientists, soil scientists, agronomists, and even two economists to conduct the program - including Eliot Epstein, Patricia Millner, John Walker and Rufus Chaney. Nevertheless, when we came together as a research team, very few of us knew very much about either sewage sludge or composting. Thus, we proceeded to take our places on the learning curve.”
Parr then described problems encountered at the composting facility and solutions achieved. Lesson No. 1 -”It's difficult to conduct research trials at a compost production facility - but not impossible.” The sludge - 150 to 200 wet tons delivered to the pad daily had to be dumped appropriately, mixed with wood chips or other bulking material, built into windrows (or later, aerated piles) , periodically turned, then after 30 days placed in curing piles for four to six weeks. Material was finally screened to recover wood chips, and finished compost was placed in storage piles.
“Meanwhile,” Parr explained, “we were trying to determine effects of such variables as sludge/bulking agent mix ratios, temperatures, moisture content and windrow turning frequency on the composting process, screening and product quality. A logical solution might have been to separate production entirely from research, but before too long, observation and intuition came to the forefront, and both initiatives - production and research - began to feed off one another, somewhat symbiotically.”
Another lesson the research team learned was that the windrow method was not adequate for composting raw-limed sludge because of the high potential for odor emissions. “Temperature monitoring indicated that we were not getting far enough into the desired thermophilic range for good composting to occur. Not surprisingly, odor problems intensified. The situation became even worse when it started to rain, and a temperature inversion settled over the composting site. Then we ran out of wood chips, and we created 'one big stink.' Our phones rang constantly; we stopped traffic on the Baltimore-Washington Parkway and were soon visited by a U.S. Congresswoman who demanded an explanation. After getting it, she advised us to shut down immediately and to go back to the drawing board, which we did. This was how the Beltsville Aerated Pile method of sludge composting was conceived.”
A final lesson for the research team was how critical it is to develop and maintain good public relations (PR) with people and communities in close proximity to a sewage sludge composting facility. “Usually scientists, engineers and laboratory directors are reluctant to engage in PR and believe they can go it alone,” observes Parr. But on issues as sensitive as composting/recycling of sewage sludge (i.e., biosolids) or MSW, it's pretty important to have most of the public on your side. I've really been impressed by how supportive the public can be if they know what you're trying to do, and why it's important. Some neighbors suggested that they'd be even more supportive if they could get some compost for their lawns/gardens. By then, we were generating a very high-quality product, so on alternate Saturday mornings, we opened the gate so each family could get a few sacks of compost.”
Our thanks to Jim Parr for his recollections of research experiences while he directed the USDA-ARS Biological Waste Management Laboratory at Beltsville, Maryland. And our thanks to Compost Science & Utilization Art Director Doug Pinkerton and Production Coordinator Celeste Madtes for having made the transition to a larger-size format so well done for us all. - J.G.