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Composting

What Is Composting?

Composting is the natural process by which organic materials (e.g. food waste, yard waste, plants, etc.) decompose into a nutrient-rich soil amendment known as compost. The difference between composting and natural decomposition is that composting is purposefully managed. A banana peel thrown on the ground will decompose, but will not create compost. However, the same peel placed with other organic material in a pile will break down into compost.

There are a number of different ways composting can be achieved. There are 3 common types:

Aerobic composting: This is the type of composting that occurs in backyard compost piles, other outdoor composting operations and certain enclosed composting systems (often called "invessel composters"). Organic matter is broken down by bacteria naturally found in the soil. The term "aerobic" means that this process requires oxygen (just like aerobic exercise!); specifically, the bacteria that decompose the material require oxygen to do their job. Compost piles must be occasionally turned or stirred up to ensure that the bacteria are getting the oxygen that they need to breakdown the organics without producing bad odors (we'll get to that next…).

Anaerobic composting: This is the type of composting that occurs in enclosed composting systems called “digesters” or “anaerobic digesters.” Organic matter is broken down by anaerobic bacteria, meaning that the bacteria work without oxygen (the opposite of the term ‘aerobic’). These systems are kept enclosed for 2 reasons: 1. the presence of oxygen can be better managed indoors and 2. one of the byproducts from this process is methane, an odorous gas. While anaerobic composting smells terribly, the methane generated can be used as a fuel source. If an aerobic composting operation isn’t managed properly and the bacteria don’t receive the oxygen they need to thrive, the compost pile will “go anaerobic,” begin creating methane and STINK! An outdoor composting operation that smells badly is a poorly managed composting operation for this very reason.

Vermicomposting: This is an aerobic type of composting that relies heavily on worms to breakdown the organic matter instead of just bacteria. One of the benefits of this system is that it can be done indoors! “Vermi” is Latin for “worm” and a vented bin with some shredded paper, food waste and worms is all that is required to begin a vermicomposting system. Mary Appelhof is a great resource for more information about vermicomposting.

See anything incorrect and you want to call us out? Does something not make any sense at all? Just have a question? Email us!!! recycle@umich.edu

Don’t Compostable and Biodegradable Mean the Same Thing?

No. Uh-uh. Not in your life. No-sir-ee-Bob.

Here’s a great explanation of the difference

Well, biodegradable is still good for the earth because these items breakdown in a landfill, right? That’s what the vendor told me…

WRONG! Landfills are designed to prevent items from breaking down. Learn more here.

See anything incorrect and you want to call us out? Does something not make any sense at all? Just have a question? Email us!!! Recycle (get address) (54.205.166.220)

Does U-M Compost?

The short answer: YES! Read on for the long answer…

Yard waste composting: U-M Grounds has composted yard waste from campus for many years. This is an aerobic composting operation and the finished compost is used throughout campus. Additionally, they have experimented with the use of ‘compost tea’ as a natural fertilizer. For more information on Grounds’ use of compost tea, check out these articles:

Plant Grounds and Building Services Explores Sustainable Landscape Management

Landscape chemical reductions planned for ‘normal’ spring

An In-depth Look at Using Compost Tea in Lieu of Chemical Fertilizers

Food waste composting: U-M Waste Management Services (WMS) has offered a ‘pre-consumer’ food waste composting program since 1997. Pre-consumer food waste, also known as prep waste, is unwanted or unusable foods that have not been served to people and is generated during meal preparation. This includes fruit & vegetable trimmings and peelings, spoiled produce, egg shells, stale bakery items, etc. Current participants include Betsey Barbour, East Quad, Hill Dining Center, Mary Markley, Palmer Commons, South Quad and West Quad.

In 2012, WMS began offering a ‘post-consumer’ food waste composting program. Post-consumer food waste is unwanted, leftover food that has been served to customers as well as compostable disposables. Plate scrapings, apple cores, half-eaten sandwiches, etc. are all collected and composted. Additionally, certified compostable disposables can be collected for composting. These include compostable plates, cups, flatware, bowls, napkins, etc. Many items claim to be ‘compostable’ or ‘biodegradable,’ but without certification, will not breakdown in a compost pile.

Where the Food Waste Goes

U-M does not manage the food waste compost site. We have partnered with WeCare Organics, the private operator of the City of Ann Arbor’s compost site, to compost this material for us. Once the compostables are collected from building loading docks by WMS staff, the material is taken to the City’s compost site and dumped. It is then mixed with yard waste and formed into long piles, known as windrows, where air can circulate and aid in the aerobic decomposition process. After the material has fully decomposed, the finished compost is tested to assess its potential as a fertilizer or soil amendment.

Does the Composted Food Waste Come Back to U-M?

Not really. The majority of our compost needs are served by the compost generated from U-M yard waste at our Grounds facility. Occasionally, we need to purchase additional compost from WeCare Organics, so there is a chance that it contains food waste from U-M. However, as the Ann Arbor Compost Site accepts organics from so many places, we can’t guarantee it.

See anything incorrect and you want to call us out? Does something not make any sense at all? Just have a question? Email us!!! Recycle (get address) (54.205.166.220)

History of Food Waste Composting U-M

How Did the Food Waste Composting Program Begin?

In March 1997, U-M Waste Management Services and the City of Ann Arbor Solid Waste Department received a grant from the Washtenaw County Department of Public Works to pilot the program. This grant covered the costs to test the technical and economic feasibility of adding pre-consumer food waste to the City’s compost site and targeted East Quad, Markley and South Quad. During the 8-month pilot, more than 30 tons of food waste was collected. The pilot was considered a success and was adopted as a new program.

Why Did the Program Begin with Pre-Consumer Food Waste? Why Not All Food Waste?

We like to be arbitrarily selective, that’s why. Just kidding! Since it takes different site management to compost food waste that contains vermin-attracting items like meats, oils, fats, bones and cheeses, the City of Ann Arbor was uncomfortable accepting these items. However, when management of the site was turned over to WeCare Organics, they brought the expertise needed to accept these types of items and U-M was able to expand what we took to them to all of those items that make food taste good. Mmmmm…… cheese.

We started to move into the post-consumer food waste realm with a composting pilot in conjunction with the Michigan League in Fall 2012. This pilot was the result of the recommendations offered in the Post-Consumer Composting Study (2010). Patrons of Beanster’s Café, Taco Bell and Wendy’s had the opportunity to compost any leftover food waste, napkins and certain other wastes in specially-marked compost bins. Click here for the full pilot report.

Why Isn’t All Food Waste Generated at U-M Composted?

Short answer: It’s expensive and contamination.

Long answer: Here in Michigan, we are blessed and cursed by having ample landfill space. All of this space means that it doesn’t cost anyone within the state a lot of get rid of trash, which means we have more money in our pockets. In fact, Michigan is actually a trash importer, with most of the trash coming from Canada. Unfortunately, since it is so cheap to landfill, the economic argument for composting is thin, if existent at all. Since composting takes more labor and equipment to manage than landfilling, it’s more expensive. And no, the revenue for the compost sold doesn’t make up for the costs associated with site management.

While U-M is committed to the environment, we are also committed to the students and Michigan residents to use their tuition and tax dollars in the best manner possible. There are so many competing needs for every dollar, including keeping tuition down, new facilities, environmental goals, etc. that composting has yet to rise to the top of the heap.

The second reason all food waste isn’t yet composted is contamination. Contamination is a HUGE concern when it comes to the composting process. While many assume that diverting wastes to compost is just like recycling, it couldn’t be farther from the truth. Here at U-M, we send our mixed recyclables to a Materials Recovery Facility (MRF) where they are sorted, baled and sold. If non-recyclables are mixed in, it’s not that big of an issue because they are sorted out - in fact, U-M is allowed up to a 9% contamination rate in our recyclables. However, compostables are not sorted. Since compost sites typically deal with yard waste, there hasn’t been a need to sort the incoming material. As a result, any non-compostable items mixed in stay that way through the composting process and result in compost with bits of trash in it. No one wants to buy compost with trash in it to put on their crops, garden, etc. As a result, we need to ensure that there is no contamination in the food waste we send to the compost site. Collecting contaminant-free, or clean, compostables is relatively simple in places like prep-kitchens, dining halls and catering operations where trained staff are the ones deciding where the waste should go. In areas where the campus community are generating compostables, like coffee shops, fast food restaurants and events, this gets to be much more difficult. It will take a full culture shift on campus before collecting food waste from these types of locations is achievable; this is a shift we are trying to begin.

See anything incorrect and you want to call us out? Does something not make any sense at all? Just have a question? Email us!!! Recycle (get address) (54.205.166.220)

How Can I Start Composting at My Building?

We have minimum requirements for participation in the food waste composting program. You must meet all of the following:

The cost to participate is $12.50/cart/pick up. Charges are assessed by the number of carts emptied. A work request must be issued through the Plant Operations Call Center (647-2059) for the service after meeting with representatives from U-M WMS. Pickups occur on Mondays, Wednesdays and Fridays between 7 am and 1 pm. Participants who have ongoing contamination issues will be removed from the program.

The first step is to email us at Recycle (get address) (54.205.166.220) to express your interest in participating in the program. See anything incorrect and you want to call us out? Does something not make any sense at all? Just have a question? Email us!!! Recycle (get address) (54.205.166.220)

How Can I Compost at My Event?

Offering food waste composting at campus events is becoming more and more popular. Here are the minimum requirements:

For more suggestions on composting at your event, please visit the Zero Waste Event Guide.

See anything incorrect and you want to call us out? Does something not make any sense at all? Just have a question? Email us!!! Recycle (get address) (54.205.166.220)

Where Can I Find Compostable Products?

Since we are a U-M department, we’re not allowed to recommend or promote any specific products. No, seriously, we can’t. However, here is a link that will allow you to search for products. Remember, we’re not endorsing any of these, in case someone asks.

See anything incorrect and you want to call us out? Does something not make any sense at all? Just have a question? Email us!!! Recycle (get address) (54.205.166.220)

Latest Developments

The Waste Reduction and Recycling Office (WRRO) piloted a post-consumer food waste composting pilot in conjunction with the Michigan League in the Fall 2012 semester. This pilot resulted from the recommendations offered in the Post-Consumer Composting Study published in 2010 and marks the University's first step towards institutionalized post-consumer food waste composting.

Patrons of Beanster's Café and the League Underground (featuring Taco Bell and Wendy’s) were able to compost any leftover food waste, napkins and certain other wastes in specially-marked compost bins. Read the full report of the pilot.

In 2010, the University of Michigan Recycling Program contracted with Resource Recycling Systems, Inc. to produce a feasibility study and business case for an on-campus, post-consumer food waste composting program. The report can be found here.

We continue to look for opportunities to compost post-consumer food waste. Check back often for updates!

See anything incorrect and you want to call us out? Does something not make any sense at all? Just have a question? Email us!!! Recycle (get address) (54.205.166.220)


Content modified: Jul 3, 2013