Maximizing the Efficiency

of a Large-Scale Vermicomposting Project

June 2011

Student Investigators:

Joey Kotnour, Biology

Leah Schiller, Medical Laboratory Science

Kayla Wandsnider, Biology

Faculty Supervisor:

Dr. Ryan Perroy, Department of Geography & Earth Science

University of Wisconsin-La Crosse

UNIVERSITY OF WISCONSIN SYSTEM

SOLID WASTE RESEARCH PROGRAM

Introduction

The objectives of this grant were threefold: (1) to establish best practices for operating

and maintaining the newly purchased University of Wisconsin-La Crosse (UW-L)

vermicomposting system, (2) to collect reference data on composting programs at other

universities across the nation, and (3) to develop educational materials for the UW-L community

on the benefits and importance of vermicomposting and recycling food waste in general.

Background

A student–based campus composting program was established at the University of

Wisconsin-La Crosse in 2002 and expanded dramatically in 2009-2010. The expanded program

was very successful on the collection end, but quickly outgrew on-campus space and facilities.

Poor maintenance of the collected compost feedstock led to the termination of the project and

possible termination of composting at UW-L. The solution to this problem was to find a more

efficient way to compost at a large scale, thus vermicomposting became an area of interest.

UW-L worked with Hillview Greenhouse, a local non-profit organization, on designing a plan to

locate and operate a vermicomposting system. Hillview would have ownership of the produced

worm castings in return for housing and maintaining the vermicomposting system, and UW-L

would have a more sustainable means of dealing with the hundreds of pounds of food scraps

generated on a daily basis.

Funds for the 5’ x 32’ UWL vermicomposting unit were secured from the UW-L student

fee-based Green Fund in the summer of 2010. Three UW-L undergraduate students received a

University of Wisconsin System Solid Waste Research Grant to work on the program and

research how to implement an effective vermicomposting system. The original goals of the

project were to determine the most efficient and effective method for the food waste collection

and vermicomposting process. However, delays in the project associated with closure of the

Hillview Greenhouse impacted these goals. An alternative warehouse site was eventually located

approximately two miles from the UW-L campus. In December, 2010, the vermicomposting

machine was delivered and assembled in the warehouse. Campus pre-consumer food waste

collection eventually began in January of 2011. The program will expand to include both pre-

and post-consumer food waste in the fall of 2011.

This report will present results generated in meeting the three objectives of this grant: to

establish best practices for operating and maintaining the vermicomposting system, to collect

reference data on composting programs at other universities across the nation, and to develop

vermicomposting educational materials.

Methods

Determining Vermicomposting Best Practices

Vermicomposting is a feasible option for diverting large quantities of organics from the

waste stream. A growing number of economically viable, industrial-sized vermiculture programs

now exist, processing between 5 and 500 tons of compostable feedstock per month while also

producing valuable agricultural products (Sherman, 2000; Aalok et al., 2008). However,

vermicomposting on a large scale remains a relatively new field and specific conditions and

management practices can vary dramatically. A variety of data were collected in order to

effectively implement the UW-L vermicomposting program. These data included daily and

weekly logs of the amounts and types of food waste generated (including materials that had been

‘pre-composted’) and added to the bin (Figure 1) and temperature, relative humidity, and oxygen

readings from wireless sensors installed throughout four ‘sections’ (A, B, C, and D) of the

vermicomposting system (Figure 2).

Figure 1. Example of daily log of food waste and compost matrials added to the UW-L

vermicomposting system. Right photo is of Zach Gaugush from Hillview Urban Agriculture Center,

feeding the bin.

Date Food type

Weight (lb)

5/16/2011 Bin A

Veggies 60

Finished compost

90

5/17/2011 Bin C

Veggies 120

Compost 120

5/18/2011 Bin D

Veggies 120

Compost 120

5/19/2011 Bin A

Veggies 60

Compost 100

Figure 2. Array of oxygen, temperature and humidity probes to measure conditions in the

bin in four ‘sections’ (A, B, C, and D). Joey Kotnour setting up a temperature probe for the

vermicomposting system (inset).

National-Level Trends in University Composting

Data on composting from universities nation-wide were collected via telephone and e-

mail interviews. Once identified, colleges and universities known to compost were interviewed

with standard questions designed to create an understanding of each respective compost program

(appendix B). From these interviews, responses were compiled into a table that was used to find

patterns in each type of program. Questions asked included: composting methods used, whether

or not it was on campus or done through another company, the types of materials collected, age

of the program, pounds per week collected, and solutions to any contamination issues.

All data obtained from composting schools was provided by persons actively working

with the compost (collection or the process itself); most often the responders were from the

university’s facilities department or dining services, and occasionally students. From this, a

transcript of the interview was kept and used to determine what questions should be used for

comparative purposes. The responses to these questions were then gathered into a table and

analyzed. Although vermicomposting schools remain rare, businesses with vermicomposting

systems were also interviewed to find methods beneficial for vermicomposting.

Vermicomposting Educational Materials

Part of having an effective pilot program is to employ useful education techniques. We

created and produced a video to help explain and persuade viewers on the benefits of recycling

food waste and vermicomposting:

(http://dl.dropbox.com/u/14190/Vermicomposting%20Slideshow.mp4).

The main purpose of such a video is to persuade the viewer to feel compelled enough to help

compost and spread the word on composting. This video will be shown to the UW-L student

body approximately one month into the fall semester after the vermicomposting system has been

up and running with both pre- and post-consumer food waste. We will closely monitor collected

foodstock weights to determine if there is any measurable effect of the video.

Class demonstrations were another method to help inform UW-L students about

composting. Over 160 students from four different UW-L geography classes were taken to the

vermicomposter and shown the system first hand (Figure 3). The demonstration hopefully

sparked the interest of some students and will help expand the success of the project. These class

demonstrations will be incorporated more fully in UW-L geography curricula, and other

departments have also expressed interest. A survey was also produced to help determine the

effect of the educational methods on participation in vermicomposting (Appendix A).

Figure 3. Demonstration of the vermicomposting system to an introductory UW-L geography class

Results

Determining Vermicomposting Best Practices

Data from recorded food waste collection logs and installed sensors within the vermicomposting

bin are shown below.

Figure 4. Collected Food waste totals collected from UWL Pre-consumer waste program.

Figure 5. Example temperature data collected by installed temperature and humidity

probes in section D. Temperature fluctuations correspond to the type, amount, and timing

of food waste inputs. Temperature peak at ~6/20/11 is related to overfeeding of bin.

Figure 6. Snapshot of temperature data collected by four ‘sensor towers’ installed

throughout the vermicomposting bin. Colored squares are data from individual sensors

(dark blue vertical bands between colored data are simply to separate bin data and do not

represent temperature readings).

Figure 7. Example of initial oxygen data collected by two probes within Bin A section at

depths of 10 and 40 cm.

DISCUSSION

Determining Vermicomposting Best Practices

Initial results from the sensor array suggest that our former practice of dumping large

amounts (>100 lbs at a time) of whole food scraps into individual sections of the bin was not

optimal. The large particle size of the food particles makes it harder for the worms to break it

down, and instead of immediately vermicomposting we are producing a hybrid

composting/vermicomposting cycle. This produced elevated temperatures in the bin that are

above the suggested tolerance levels of the worms. As the bin is quite large we believe that the

worms are able to migrate away from the affected area until the composting cycle has finished.

Although we are not losing significant numbers (if any) of worms, this is not optimal. We have

recently purchased a Mackissic 12PTE shredder/chipper to reduce particle size, and this, along

with smaller amounts of feedstock additions, will likely improve efficiency. An initial ‘harvest’

of worm castings in early June, 2011 produced >400 pounds of finished castings.

Vermicomposting Educational Materials

The educational materials produced as a result of this grant will be employed in the fall of

2012 and a study will be conducted to determine their effectiveness. We believe that they will be

a useful component in ensuring that the UW-L vermicomposting program enjoys high

compliance and participation.

National-level Trends in University Composting

Figure 8. Map indicating the occurance of and type of U.S. university composting for 17 campuses

A total of seventeen universities participated in an interview regarding their composting

programs (Figure 8). A list of participating universities is given in Appendix C. Of these, a wide

variety of composting types were represented, and several strong patterns emerged (Figure 9).

These patterns allow campuses considering composting programs to understand the realistic

limits and possibilities of various composting methods and systems. From this data, the strongest

trend found was that most composting programs were fairly young. Of the campuses

interviewed, 59% started composting in 2007 or later. Another interesting trend proved young

but strong: the use of a secondary composting company.

Figure 9. Flowchart illustrating results from collected U.S. university composting survey data

These companies are usually paid for hauling away compostable materials from campus

and then compost the materials on their own property. Almost half of the schools interviewed

were participating in a program like this, but none had been doing so before 2007.

For different campuses, certain factors were more important in the success of the program

than others. Several campuses with farms or a waste management program had originally tried

on-campus composting programs, but found that it was too much to handle and had reverted to a

secondary company where all they had to do was pay a tipping fee. These campuses usually had

a farm that generated large amounts of compostable materials. Interestingly enough, both

continued to compost farm scrap, approximately 175,000 lbs/week, but used a secondary

compost company for the campus food scrap. This way, they were able to use compostable

disposables (which decrease the quality of compost1), but the farm didn’t have to deal with

associated contamination issues and slow decomposition rate. Other schools initiating a

composting program chose a secondary company because there was little overhead cost, but

hoped to find enough funding to compost on-campus at a later date. This was quite an interesting

paradox. While being able to compost on-campus can be cheaper and more sustainable in the

long run, it requires more space, more equipment, and often, more employees.

Composting habits were very clearly divided by whether composting was done though a

secondary company. While all colleges interviewed collected compostable materials, only 53%

of them composted themselves. While these schools were able to provide little information on

composting processes, they were valuable in determining successful methods for collecting

compostables. It was clear there are strong advantages and disadvantages to all methods.

For schools that used a secondary company, there were two categories: those that wanted

to compost but didn’t want to deal with the logistics and extra labor, or those that were unable to

purchase the equipment necessary for their own composting operation but wanted to compost.

The former was usually content to continue using another company. The latter usually wanted to

purchase a system in the future, but were still working out the logistics.

Schools that used secondary companies were able to compost a wider range of materials

as well. Meat and dairy were collected at 87% of these schools because composting companies

achieve a high enough temperature to kill any pathogens. These schools also composted a larger

range of non-food materials, everything from compostable forks to paper towels from bathrooms,

largely because they didn’t have to deal with the end-product. Compostable dinnerware is known

to decompose at a slower rate than food scraps, and decreases the quality of the end product.

Often, it must be screened out of the finished product and composted through another cycle1.

However, 87% of these schools were able to collect these materials, compared to only 44% of

schools that composted themselves.

For schools that composted on campus, there was a wide range in systems used, weights

collected, and materials collected. Each school had their own way of doing things that wasn’t

quite the same as anyone else. However, there was an interesting pattern with schools that also

had an agricultural program. Three schools interviewed had fairly large campus farms. Two of

these had livestock as well. These two schools had originally composted campus food scrap, but

with the move to compostable dinnerware and an increase in weights, both schools decided to

send their food scrap to secondary composting companies but continued to compost large

amounts of farm generated materials and manure.

1 See http://www.vermontcynic.com/life/no-more-forks-in-the-compost-pile-for-uvm-1.2197664 or

http://myplasticfreelife.com/2010/03/are-compostable-utensils-really-compostable/

Schools that composted on their own all wanted to collect as much as possible, but

understood that quality decreases with compostable plastics and that more time and higher

temperatures are required. Only 44% of these schools collected compostable dinnerware.

Schools also understood that collection of meat and dairy would require meeting complicated

regulations and reaching high temperatures to kill pathogens. Only 44% of these schools

composted meat compared to 100% of the composting companies observed in this study.

Interestingly enough, schools that took meat and dairy didn’t always take compostable

dinnerware and vice versa.

National-level Trends in University Composting

From the compost program interviews, it became quite clear that it is not possible to

create one program that would be feasible and successful for every college. However, some

programs work well on small and large scales but other programs are less flexible. It was also

found that schools are creative in their composting quest. One of the schools interviewed

collected food scrap exclusively, but sent it to a local farmer who then heated it and fed it to his

livestock. A program like this is an innovative idea that should be explored by more schools as it

decreases the amount of land, water, fertilizer, etc. needed to grow feed.

The divide between colleges that compost independently and those that use outside

companies produced both advantages and disadvantages. For each school’s program, the

possibilities of what materials can be composted varied, and as a result, so did the advantages

and disadvantages. Schools that are able to compost on campus can become more sustainable

because they use less fossil fuel for transport and have a finished product readily available to

replace some conventional fertilizer use. Yet they are often unable to accept meat, dairy,

compostable disposables, paper products, etc.: things which then get thrown away, decreasing

the total amount of waste diverted. Composting companies that may transport compost further

distances are generally able to accept more materials, decreasing the amount of waste burned or

added to landfills.

For schools interviewed that hope to change their program, and for schools who hope to

start composting in some form, this gathered information may prove quite useful in creating a

successful composting program. While it should be noted that no program can be recreated

exactly, as weather, campus population, and campus size are all large factors that can impact

composting programs, the data is an analysis of methods that are successful for small- and large-

scale programs collecting a variety of materials. Additionally, the information collected from

UW-L is more in-depth than what was collected from other schools, and will prove useful year

after year, and for other schools with and without vermicomposting programs.

References:

Aalok, A., Tripathi, A.K., Soni, P., 2008. Vermicomposting: A Better Option for Organic Solid

Waste Management J. Hum. Ecol., 24(1): 59-64.

Sherman, R., 2000. Latest Developments in Mid-to-Large Scale Vermicomposting BioCycle

Journal of Composting & Organics Composting, Vol. 41, No. 11, pp. 51-54.

Appendix A. Draft of Vermicomposting Survey for UW-La Crosse students

You may have noticed there are plastic bins set out to put you food scraps as you leave Whitney.

These food scraps get dumped into a large-scale vermi-compost bin that has been in use since

spring semester of 2011. In this bin there are more than 200,000 (200-250lbs) worms that eat

through the food. The result is worm castings. Worm castings have a high nutrient content and

are fantastic for growing anything. Now that you know a bit about what is going on would you

please take some time to fill out this survey to help us get a better understanding of what we can

do spread the word about vermi-composting.

1. Do you compost your food?

a. Yes b. No

2. If you said no, why don’t you compost?

a. Don’t know what to compost d. We compost?

b. Too much of a hassle e. Other (explain)

c. Don’t care

3. Were you exposed to the compost program last year and if so did you compost then?

a. Yes I was expose and I composted

b. Yes I was exposed, but I didn’t compost

c. I am a freshman but I still compost.

4. What do you think would make people want to compost more?

a. Movie d. Brochure

b. More posters e. Incentives

c. Workshop f. Other (explain)

5. Do you have any other comments, suggestions, or questions?

Appendix B. Compost questions for University Survey

1. What kind of compost program is being used? Ex: vermicompost, compost bins, etc.

2. How was it implemented? (ex: student, staff, faculty initiative)

3. When did composting start on your campus (year is fine)?

4. Who takes care of it/oversees it? (dining services, facilities, or designated crew)

5. Is there any cost involved? If so, who pays?

6. Where is the compost kept and how much space is used?

7. How much waste does it take (pounds/week), and what kind of food scrap is or isn’t

allowed? Is compostable dinnerware used as well?

8. Have you had any issues with contamination, especially with post-consumer?

9. Is there any literature around the campus to inform students about the program? If so,

what? Are there other means for educating students used?

10. If vermicomposting, what material do you use for bedding, and what is the ratio of

bedding to waste that you try to obtain?

11. What would you recommend to others based on your composting experience?

12. Are there any other composting schools you know of?

Appendix C. List of the 17 universities that participated in this study

University Location

Agness Scott College Decatur, GA

Allegheny College Meadville, PA

Bard College Annadale-on-Hudson, NY

Bowdoin College Brunswick, ME

Carleton Northfield, MN

Central Michigan University Mount Pleasant, MI

Cornell University Vercon, IA

Evergreen State College Olympia, WA

Grand Valley State University Allendale, MI

Harvard Law School Cambridge, MA

Ithaca College Ithaca, NY

Luther College Decorah, IA

Northland College Ashland, WI

UW-Eau Claire Eau Claire, WI

UW-Stevens point Stevens Point, WI

UW-Stout Menomonie, WI

UW-La Crosse La Crosse, WI