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A Lot to Digest with Composting on Campus
There is a certain waste stream on college and university campuses that can travel two very different paths. One path, which ends at the local landfill, leads to the uncontrolled release of methane, a greenhouse gas (GHG) 21 times more potent than carbon dioxide. The other path creates a nutrient-rich fertilizer that can be used for gardens and landscaping. This waste stream is made primarily of food scraps, and it constitutes roughly a quarter of a school’s entire waste picture.
“Your biggest waste stream that’s currently landfilled, and has a high methane generation potential, is food waste,” explains Dr. Sally Brown, associate professor at the University of Washington and renowned waste management expert. “Less than one percent of food waste in the U.S. is currently diverted from landfills.” At the household level, according to the EPA, food waste coupled with yard trimmings constitutes 24 percent of the U.S. municipal waste stream.
Schools and scientists across the country have been studying and implementing composting programs in an effort to address their food-waste stream. According to its proponents, composting not only addresses the release of methane during the foods’ decay process, it also addresses many issues tied to soil improvement measures.
“The benefits of compost use,” continues Dr. Brown, “also include fertilizer avoidance, carbon sequestration, the potential to get herbicide avoidance, and then you get a whole bunch of environmental benefits that aren’t necessarily related to greenhouse gases, such as improved water-holding capacity and increased soil tilth.” (Tilth is the measure of the health of soil, so good ’tilth’ is soil that has the proper structure and level of nutrients to grow healthy crops.)
Composting, however, comes with its own set of choices. There are several methods of composting available; each varies from one another in regards of project scope, time to reach compost maturity and price, and a laundry list of pros and cons. All of these factors have played varied roles in how colleges and universities treat their food waste, if they treat it at all.
Common large-scale composting methods include windrow piles, aerated static piles, vermicomposting (using worms), in-vessel aerobic (with oxygen) composters, as well as anaerobic (without oxygen) digesters. All of these methods use structures and equipment more advanced than a simple backyard compost bin, but the end product is pretty much the same-a nutrient-rich soil amendment.
The top two factors that come into play for colleges and universities when choosing which method will best address their composting needs are cost and space. Some schools have money, but not space. Some schools have acres they can devote to building windrow piles, but limited funds to buy an in-vessel composter. Some schools have space and money, but fear the odors associated (often wrongly) with composting.
One school trying to make a choice about composting right now is Western Michigan University (WMU). Taking all the aforementioned factors into consideration, as well as considering the environmental costs associated with energy and transportation requirements, “the one [compost method] that stands out right now is vermicomposting,” says Sarah Campbell, a post-graduate researcher for WMU. Vermicomposting uses earthworms to break down, through digestion, organic waste materials. Castings from the earthworms contain micro-organisms which are nutrient-rich and help the soil’s water-holding capacity. Vermicomposting on covered raised beds is also well-suited for colder climates.
Campbell was hired by WMU after graduating in 2007 so she could continue working on establishing a compost program that will handle all of the school’s food waste and have no-net GHG emissions, a project she started in one of her undergraduate environmental studies courses.
For Campbell, vermicomposting is one of the less-expensive, more easily managed composting methods. It will be able to handle the 262 tons of food waste generated by the 24,800-student university each year. “And people are really interested in vermicomposting,” says Campbell. “It doesn’t just seem like a waste-management thing. It’s an opportunity to get people excited about composting.” WMU is looking to launch its composting program “as soon as possible,” according to Campbell, but still needs to iron out a few financial details.
Students’ interest in composting is something that Mark Darling has seen come and go at Ithaca College over the last 15 years. Darling is Ithaca’s supervisor for recycling and resource management programs, and he was there when the school started its compost program back in 1993.
“We started composting because no one else was doing it in the community,” Darling explains, “and there wasn’t anyone who could take our food scraps.” The school built an aerated static pile at one end of their campus. This method was preferred because of its small footprint (the size of a small building) and better odor control than windrow piles.
“Up until last year, we were composting on-site,” says Darling, “and then we switched to hauling our stuff to a local composter. We just didn’t see that our composting program was furthering our educational mission. It wasn’t involved with our curriculum. We didn’t have students doing it. We had students coming out and looking at it, but it wasn’t sparking any interest, in terms of students wanting to get right in there and get dirty. So it wasn’t really a hard to make the decision to switch to an off-campus provider.”
During the 2007-2008 school year, Ithaca hauled 265 tons of food waste and compostable serving-ware six miles down the road at the cost of $40 per ton, which is cheaper than the $70 per ton it costs to remove traditional waste. The decrease in price is because food waste is a commodity for the composting business. The food waste and serving-ware diverted from the landfill was equal to roughly 15-17 percent of Ithaca’s total waste stream.
Another school spending about $40 a ton to compost its food waste, but without taking it off-campus, is Montclair State University (MSU). In the summer of 2007, MSU acquired the first large-scale, in-vessel aerobic composter in the state of New Jersey, and one of the very few university-based aerobic composters in the country.
“To date, we have processed about 50,000 pounds of food scraps,” says Dr. Nicholas Smith-Sebasto, associate professor at MSU and the one responsible for bringing the composter to campus.
Several years ago, Smith-Sebasto was asked to consider how the school could improve its role in conservation. Montclair was the first university in the nation to sign a comprehensive memorandum of understanding with the EPA about ‘green’ practices. “One of the things that seemed to be the very lowest-hanging fruit was food waste,” says Smith-Sebasto. “Our agenda is to completely eliminate food waste on campus.”
MSU’s in-vessel aerobic composter turns and mixes food scraps and wood chips (but not yard trimmings) with a large auger four times an hour, four times each day, and the result is the production of stable compost in only five days. Windrow piles can take up to six months to reach maturation.
Another important bonus to the in-vessel aerobic system used on the campus is its capability to process proteins, such as meat, fish and dairy products, which not all windrow or static pile composting methods can handle. And it’s very small. “My whole unit,” says Smith-Sebasto, “only takes up space about the size of a parking spot. You could even put this thing on a roof if you wanted to.”
Using the aerobic composter as a teaching tool, Smith-Sebasto has given hands-on demonstrations to thousands of people so far, from college and elementary school students to representatives from the EPA, local municipalities and supermarkets. “They are all absolutely blown away,” he says, “by the quality of the compost, the fact that there’s very little odor, and how quiet the system is.” Units like the one MSU uses, capable of processing two tons of food waste a day, can cost less than $25,000.
“Montclair State University is the second-largest university in the most densely-populated state in the country,” explains Smith-Sebasto. “Frank Sinatra was close, but a little bit off. It’s not, ‘if you can make it in New York, you can make it anywhere.’ I think if we can do this in New Jersey-successfully establish a food composting program in an urban school like ours-anything else is going to be easy.”
“I get three to five emails a week from people all over the country asking about this project,” says Smith-Sebasto. Many of the emails are coming from other universities, and as far away as Anchorage, Alaska. And after he explains how simply the composter works, “they all ask why in the world is everyone not doing this.”
“You know, we hear all this talk about global climate change and how are we going to reduce our impact,” says Smith-Sebasto, “and there’s a lot of grandiose ideas out there, but there’s such a rich idea that’s as simple as rotting some food, and it’s something we can do today.”
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