1) Why compost?
Organic materials make up a large part of a university waste stream.  Composting provides an alternative to incineration or land filling organics, which can be dense and have a high per ton disposal cost.  Compost improves soils water retention, aeration, and adds lost nutrients.  Composting can save the grounds department money on buying mulch, fertilizer, and pesticides.  The system may be worked into the curriculum of some courses such as sustainability, biology, soil science, ecology, etc.

2) What is compost?
Composting is nature’s way of recycling.  Composting is controlled biological reduction of organic wastes to humus.  The end product, compost, is used as a soil amendment that provides plant nutrients, supports beneficial soil life, reduces soil diseases, increases water retention in sandy soil and adds drainage to clay soils, and promotes weed and erosion control.

3) What can be composted?
Compostable materials include organics such as grass, leaves, tree limbs, shrub waste, non-hazardous animal lab waste, hand towels, paper plates, napkins, wax and paper cups, wax and non-wax cardboard, pre and post-consumer food waste such as coffee grounds, tea bags, egg shells, fruit and vegetable waste, breads, dairy products, and jello.

Non-compostable materials include oils, weeds, diseased plants, meat, bones, dairy products, cat, dog, or human waste, hazardous materials, plastic, glass, metal, treated wood, and very large items like large tree limbs or stumps.

4) Can a contractor/farm do it?
Maybe. Farms may accept yardwaste for composting.  Hog farms have been know to accept food waste as feedstock.  Call the City or County;  some areas have composting programs set up especially for yardwaste.  Local food banks may accept donations of food for the hungry.  In any of these cases the most important thing is make sure the organic material is separated correctly and meets the specifications of the accepting entity.

5) How does compost work?
Control the following parameters of a compost pile: carbon and nitrogen inputs, size and surface area exposed of inputs, moisture, air, volume and temperature.   The compost pile is full of microbes such as bacteria, actinomycetes, protozoa, and fungi.  Microbes need food, air and water for survival.  The optimum carbon: nitrogen ration is 30:1 by weight.  Examples of materials with high carbon ratios are leaves, straw, bark, paper, wood chips and sawdust.  Examples of materials with high nitrogen ratios are food waste, grass clippings and manures.  The later could create odor and vector (rodent) issues.  Shred the material before placing it in a compost pile.  This will speed up the process by increasing the amount of surface area the microbes have to work on.

The material should be moist but not soaked.  Too much water will eliminate space needed for air.  Squeeze the material and make sure it is like a damp sponge.  The optimum moisture level is approximately 40-60%.  Water should be mixed into the pile.  Composting is an aerobic process.  If the pile isn't turned, it will become an anaerobic (without oxygen) pile.  Anaerobic conditions will cause odors and create chemicals toxic to plants.  Piles should be between 27 and 125 cubic feet.  If the pile is too small it will not hold heat and if it is too large it will not get enough oxygen.  Optimum temperatures are between 90-140 F (32-60 C).  Most microbes die when temperatures rise above 160 F.  Pathogens are usually destroyed around 131F (55 C).

6) What method of composting should be used?

What and how to compost depends on many factors including regulations, space, funding, town and gown issues, and available labor.  Composting can take up anywhere from several acres to one parking space.  Methods used most often are grasscycling, piles, long rows (windrows), in-vessel, and vermicomposting.

When grass is cut and left on the lawn, it is called grasscycling.    The cut material simply decomposes on site adding beneficial organic matter to the soil reducing the need for fertilizer and reducing water evaporation.  This will not create a thatch problem.  Thatch is a mixture of roots, dead leaves and rhizomes that decompose slowly.  Grass is a rapid decomposer.

Keep the mower blades sharp, mow more often cutting less than 1” of the leaf surface, mow dry grass, and do not over-fertilize.

Piles can be any size in a container or not.  It will take a longer time for a smaller pile to decompose.  Try not to make the pile taller than the person working on it unless heavy equipment is used.   The pile will shrink and spread out.  To contain the pile, build or buy a compost bin.  There is no one way to make a compost bin.   A circle of chicken wire will work, an elaborate wood bin or a plastic or wood bin from a garden store.  Piles are usually for small scale composting although they can get as big as cars.  Depending on what is put into the pile and how it's managed, a pile can take up to six months or a year to obtain finished compost.

Aerated Piles are made the same way regular piles are made except these piles have a system to let more air in.  The system can be as simple as a pallet under the bin or as elaborate as PVC tubing with forced air inserted into the pile.   More air generally helps your system work faster.

Windrows can handle tons of organic matter.  This pile is usually long, narrow, and at least 4-ft high.  When done on a large scale this method requires heavy machinery such as a front-end loader and/or windrow turner.  Windrows can be covered or not.  This method is often used for large institutions or for cities and counties.

Tumblers are units that are containers that rotate or turn.  Some work done manually, others utilize a motor.  These units work by allowing the contents to heat up rapidly and retain moisture. Air is limited but present.  This method is for small scale but fast composting.  This type of composter is available for purchase at a garden store and home improvement centers.

In-vessel composters can compost anywhere from a few hundred pounds to over 60 tons a day.  Organic waste including meats, oils, fish, and dairy products are placed in the container and mixed, shredded, and fluffed by the composter.  Some composters are fully automated with sensors to monitor temperature, oxygen and moisture.   Biofilters are used to reduce or eliminate odors.  This is another good method for institutions with large amounts of organics.

Vermicomposting uses red wiggler (eisenia foetida) worms to do the work of composting.  Vermicomposting requires air, water and food the same way aerobic composting does but in this case you are not using the microbes, which produce heat to do the bulk of the composting work. The worms eat the organics and leave behind castings.  These systems are also available in a variety of sizes.  This can even been done using a  10-gallon container that might handle a small departments food waste.  Another option is a continuous flow system that could handle all of a large institutions food waste.

 

7) How can compostable material be collected and transported?

Once determining a method of composting, the next step is to think about how to get compostable materials collected from the source and transported to the composting operation.  For yard waste determine what is currently happening with the material and amount generated. 

Find out how the campus grounds crew collects and transports yardwaste.  If grass is currently bagged, will that work with the composting system?  Is the bag plastic, paper or biodegradable?  The grounds crew might have a routine for the entire year that can be reviewed to determine how much and what kind of material is generated.  For example: typically lots of tree or bush cuttings are generated during one time of year and more grass and flower waste another time.  Is there enough carbon material to mix with the nitrogen material?  Some composting operations have to find alternative sources of carbon and nitrogen.  Collection systems will depend on volume.  Regular trucks (including trash and dump trucks) may be utilized to collect and haul material.

If there is an opportunity to compost food waste and animal lab waste, find out how the waste is currently handled and determine how much waste is generated.  Determine whether the system will handle just pre-consumer food waste or both pre and post-consumer food waste.  Determine what type of animal lab waste that is acceptable.  Make sure to only collect non-hazardous animal lab waste.  Research any regulations concerning the disposal of this type of waste.

Education is a critical component to the success of this process.  Perform in depth training sessions with the managers of these operations.  It is important to educate the employees involved, do regular updates and reviews to keep employees focused on this process.  Select sturdy bins that have lids and wheels and place the bins to collect the most amount of material.  With a small amount of material, the collection system can be kept low tech.  A 30 or 40 gallon bin with a lid and wheels would probably do the trick for collection. Depending on the situation, a can liner may need to be used in the bin.

Keep in mind safety issues concerning lifting because food (lots of liquid) and animal waste can be heavy.  Make a place available to clean out the bins between uses. Color code bins and label them clearly.  For bin transport in a vehicle, make sure the lid is tight and the bin is strapped in.  For large-scale operations use larger bins like 60 or 90-gallon containers with lids and wheels.  Assess the need to use heavy machinery and hydraulic systems.  Examples include: using a rear, top or side loader sealed trash truck to set up an all organics collection route, using a dump truck for yardwaste, using a hydraulic lift on your truck to empty 90-gallon carts, and having a tank full of water on the truck for cleaning out empty carts on site.  Regardless of how waste is collected, be reliable in pick-ups.  Food and animal lab waste cannot sit around and wait to be collected.  Set a schedule and stick to it.

8) Should education be a part of the program?

Absolutely!   To institute a composting program in a dining hall from hundred’s of students, education is the key to success.  Signs are a must (adding photos can help as well).   During the first few weeks of school have a volunteer stand by the collection bins to explain the new program.   When composting for an event, designate volunteers to monitor the sites and educate the public on what goes into the collection bins.   For campus kitchens, educate staff and managers.   Provide periodic refresher presentations because of changes in the student body and staff.  Brochures and posted guidelines are a helpful reminder.  Include materials in new employee and new student training,orientations.  If possible, take the staff (including anyone who's involved in the process) out to the composting site to explain the process, savings and resulting applications.

If hand towel waste is integrated into the composting collection, don't forget to train the housekeeping staff.  Don’t forget to include faculty and administrators in the education efforts.  Articles in the school paper, broadcast e-mail, posters, bulletin boards, etc. are all good ways to get the message out.  Provide the campus with updates on the progress of the program.  It's good PR while also reminding the campus about the collection process.  Post signnage in a prominent garden that refers to the use of compost made right on campus from materials found on campus.  This is a great way to educate everyone on a closed loop system.

9) What to do with the compost?

Finished compost should be fine, dark, sweet smelling, have a pH that is 7.0-9.0, and is no longer heating up.  Depending on what is composted and the method for doing it, it might be necessary to screen the compost to take out larger unfinished pieces.  Determine how fine to make the end product.  Compost can be used as mulch around shrubs, trees, flowers and on paths, as soil amendment to break up clay type soils or bind sandy soils, as a lawn top-dressing or use it in houseplants.  Many people use compost in gardens instead of chemical fertilizers to provide nutrients to their plants.  It is also commonly thought that using compost can reduce or eliminate the need for chemical pesticides.  Placing finished compost in a cloth bag and letting that sit in a bucket of water for 3-5 days, makes compost tea, a nutrient rich liquid.

10) What special issues should you consider?

Funding is usually the first concern for any project.  How much to budget will depend on the degree of technology to be used.  Site concerns are important mostly in urban areas.  In these areas, be sure and educate the neighbors.  Controlling odors is very important.  Composting will not create unpleasant smells if it is managed correctly.  Find out the regulations to perform this operation in the chosen site.  The regulations may allow composting but they may call for only certain methods of composting.  Compost can also be tested to assess the variety of nutrients in the finished product.  This will help determine correct applications (and also help trouble-shoot any problems that arise).

Resources

Composting for Kids
http://aggie-horticulture.tamu.edu/sustainable/slidesets/kidscompost/cover.html

Cornell Composting Page
http://compost.css.cornell.edu/Composting_homepage.html

Earth 911
http://www.earth911.org/master.asp?s=lib&a=organics/organics.asp

EPA Composting
http://www.epa.gov/msw/compost.htm

Humbolt State University Composting
http://www.humboldt.edu/~recycle/

Ithaca Coomposting
http://www.ithaca.edu/remp/Composting.htm

Master Composter
http://www.mastercomposter.com/

MUSC Vermicomposting
http://www.musc.edu/recycle/vermicompost.htm

Rice Environmental Progress Report Go to Compost Section
http://www.ruf.rice.edu/~envintrn/report99/ruepr99.html

UNC Chapel Hill Animal Bedding Recycling
http://www.fac.unc.edu/WasteReduction/Recyclables/animal_bedding.asp

UNC Charlotte
http://facilities.uncc.edu/Recycling/Compost/Default.htm

University of Oregon Composting
http://darkwing.uoregon.edu/~recycle/Composting.htm

US Composting Council
http://compostingcouncil.org/index.cfm