ISOSWO/APWA 2015 Spring Conference

1. Food Waste Composting
Technical Aspects and Regulatory
Requirements
Jenny Trent
The Iowa Waste Reduction Center and the University of Northern
Iowa are equal opportunity providers and employers.

2. Rural Utilities Service, United
States Department of Agriculture
• One year grant
• Reduce food waste through composting education
and outreach
• Target rural counties in Iowa
• Update the current website to promote composting
throughout Iowa
• Foodwaste.iwrc.org
This material is based upon work supported under a grant by the Rural Utilities Service,
United States Department of Agriculture. Any opinions, findings, and conclusions or
recommendations expressed in this material are solely the responsibility of the authors
and do not necessarily represent the official views of the Rural Utilities Service

3. Benefits of Compost
 Provides valuable macro and micro-nutrients to soil
 Improves water holding capacity of soil
 Wards off plant diseases
 Provides significant quantities of organic matter
 Provides beneficial microorganisms to soils
 Feeds the soil unlike fertilizer which feeds plants

4. Creating Compost
Key Process Variables
• Feedstocks
Carbon
Nitrogen
Bulking agents
• Pile moisture
• Bulk density
• Pile aeration
• Pile temperature
• Compost curing

5. Feedstocks – Carbon and Nitrogen
Carbon - Browns Nitrogen – Greens

6. Photo by Ronny Navarro
United States Composting Council – Compost Operations Training Course, Pomona, CA

7. Carbon-to-Nitrogen Ratio 30:1
High Carbon - Browns
• Corn Stalks 75:1
• Straw 75:1
• Wood Chips 400:1
• Newspaper 175:1
• Leaves 60:1
High Nitrogen - Greens
• Food Scraps 20:1
• Coffee Grounds 20:1
• Grass 20:1
• Seaweed 19:1
• Weeds 30:1
In general, three parts of carbon to one part of nitrogen

8. Bulking Agents
• Bulking agents are used to
add structure to a compost
pile.
• Bulking agents promote pore
spaces allowing for more
oxygen through the pile
• Bulking agents are carbon
sources
• Wood chips or mulch, leaves
and yard trimmings, corn
cobs and stalks, hay or straw.

9. Who are the decomposers?
Bacteria
• Mesopyillic - ambient to 110 F
break down soluble, readily degradable
sugars and starches
• Thermophillic - 110 - 170 F
break down proteins and fats and work with
actinomycetes to begin breakdown of cellulose and lignin
Fungi
• include molds and yeast and prefer 70 - 75 F and digest carbon
Actinomycetes
• break down cellulose and lignin (wood chips, paper)
• causes the pleasant earthy smell of compost
• white cob-webby like substance in the cooler edges of the pile and during
curing
• Optimum temperature is 70 - 75 F

10. Microorganisms have requirements:
1. Carbon for energy – microorganisms oxidize carbon
2. Nitrogen for growth and reproduction
3. Oxygen to aid in decomposition and oxidation of carbon
4. Water to maintain activity without causing anaerobic conditions
Illustration from Saba Cooperative

11. How do microbes obtain energy?
Microbes need to consume feedstocks to:
1. Obtain energy
2. Obtain nutrients
3. As a by-product of microbe metabolism, heat is
generated

12. Actinomycetes

13. Pile Moisture
• Moisture is essential for microbes to break down feedstocks
• Moisture > 65% means all pore spaces will be filled and the pile
will become anaerobic and will STINK
• Moisture < 40% result in fungus dominating and dust problems
• Moisture should be about 45% – 60%
• Better to begin on the high end of moisture content percent
• At 60% moisture content, you can squeeze drops of water out of
a handful of compost
• 25 gallons of water per ton of compost raises moisture content
by about 10%

14. Moisture Hand Squeeze Test
1. Reach into the pile and grab a handful of compost
2. Squeeze the material hard, check for drips
3. Release your grip and allow material to stay in your hand, smear
some between finger and thumb
4. Inspect the material
• If the material sticks together and drips, and your hand is wet
and dripping, the material is around 60% moisture.
• If the material sticks together, and your hand is moist, the
material is around 50% moisture.
• If the material is crumbly and doesn’t stick together and your
hand is dry, the material is about 40% moisture.

15. Moisture – Hand Squeeze Test
Photo by Ronny Navarro

16. Bulk DensityBulk density is a measure of the density of the compost and is a
measure of mass per unit volume. Bulk density is directly related to
porosity and free air space. The higher the bulk density, the more
dense the compost is and the less air the compost can accomodate.
The Lower the bulk density, the greater porosity and free air space.
• <800 lbs/cy may not hold heat
• 800-1000 lbs/cy just right
• 1000-1200 lbs/cy heavy, requires extra aeration and tends to
become anaerobic
• >1200 lbs/cy too dense, very difficult to compost

17. Bulk Density is directly related to porosity

18. Bulk Density Test
Bucket Drop Method
1. Mark the inside of a 5-gallon bucket at 1/3 and 2/3 fill levels
2. Tare the bucket and record
3. Fill the bucket to the 1/3 line with compost
4. Drop the bucket from a height of 6-inches ten times without spilling
the compost
5. Fill the bucket with compost to the 2/3 line and repeat step #4
6. Fill the bucket to the rim. Repeat step 4 again.
7. Fill the bucket to the rim again but do not drop the bucket.
8. Weigh the bucket and record the weight. Subtract the tare weight.
9. Divide the weight of the material by 0.025 (the volume of the bucket
in cubic yards. This will give you the Bulk Density in pounds per cubic
yard.

19. Pile Aeration
1. It’s important to turn your compost pile to introduce oxygen, but to
also mix materials and moisture so everything is composted evenly.
2. Pockets can form in the compost pile that are anaerobic, so turning
the compost will mix these pockets and introduce air.
3. The lack of oxygen is the main reason for odors in a compost pile.
Turn windrows/piles 2 to 3 times per week. Also, turn
when oxygen levels drop to below 5%.

20. Source: Matt Cotton USCC

21. Pile Temperature
• Higher temperatures results in faster breakdown of materials
• Moisture moderates temperature fluctuations
• Most pathogens and weeds are killed at temperatures above 130° F
for three days
• Temperatures above 160° F decreases microbial diversity and actually
slows composting
• Ideal temperature of compost is 130-150° F
• If compost pile gets above 170° F spread it out lowering the pile to
help decrease the temperature

22. Photo by Ronny Navarro

23. Compost Curing
The time it takes to cure compost to the finished product depends on
everything we’ve discussed so far. Generally, cured finished compost
looks like dirt and smells like dirt. But unfinished compost can contain
ammonia and organic acids, which will inhibit plant growth.
The best way to check if your compost is finished is to plant a few
radish or cucumber seeds in cups full of compost. If they grow into
healthy radishes, the compost is ready. This is called a bioassay test.

24. Compost
Calculator
Customize your
own feedstock
recipe using Green
Mountain
Technologies
Compost Calculator

25. Iowa City Landfill Compost Facility

26. Cedar Rapids/Linn County Solid Waste Agency

27. Chamness Technology – Eddyville, Iowa

28. Mitigating Problems
The most common complaint with composting facilities is
odor
• Cap your compost piles with cured compost to decrease odors
• Turn your compost often
• Adding carbon feedstocks can help reduce odors.
• Deal with every complaint and have a backup plan
• Be a good neighbor, involve the community

29. So, how do you start a composting
facility at your location?
Three Options
1. Compost your own food waste on your own land and use
the compost only on your land = no permit
2. Compost outside sources of food waste but accept less
than two tons per week = no permit
3. Compost outside sources of food waste accepting more
than two tons per week = need a permit

30. Solid Waste Composting Facilities Permit
Regulations
Iowa Administrative Code Chapter 105
Selecting Composting Location
• 500 feet from existing inhabited residence
• Outside wetlands
• 200 feet from public wells
• 100 feet from private wells
• 50 feet from property lines
• 100 feet from streams, lakes, or ponds
• If inside the 100-year flood plain, other local and departmental
regulations must be followed

31. Solid Waste Composting Facilities Permit
Requirements
• Leachate must be minimized
• Prevention of water running onto or off the facility
• Runoff needs to be properly manages
• Facility must be designed to minimize ponding of liquids
oPonding must be corrected within 48 hours

32. Surface Requirements
Composting must be done on an all weather surface that will allow
accessibility during bad weather. These surfaces must also prevent
contamination of surface water and groundwater.
• Compacted soil
• Compacted granular aggregates
• Asphalt
• Concrete

33. No Infectious Waste is Allowed
•Contaminated sharps
•Cultures
•Blood or blood products
•Pathological waste
•Contaminated animal carcasses

34. Nuisance Laws – odors, dust, noise, litter
Iowa Administrative Code 657.1
Whatever is injurious to health, indecent, or unreasonable offensive to
the senses, or an obstruction to the free use of property, so as
essentially to interfere unreasonably with the comfortable enjoyment
of life or property, is a nuisance, and a civil action by ordinary
proceedings may be brought to enjoin and abate the nuisance and to
recover damages sustained on account of the nuisance.

35. Storage and Sale of Compost
• Storage is limited to 18 months
• Sale of compost requires both a license and registration with the Iowa
Department of Agriculture and Land Stewardship (IAC Chapter 200) –
fees apply.
• Guaranteed Analysis must be completed for nutrient content and
included on the label of packaged compost.
• Inspection fees paid twice per year and includes a semi-annual
statement stating the number of net tons distributed in Iowa by grade
for each county for preceding six months.

36. Labels
The following must be included on the label of packages or
included on a printed statement when sold in bulk :
• Net weight
• Name and address of the registrant
• Name of the product
• Brand
• Grade (the percent of total nitrogen, available phosphorus or P2O5 or both,
and soluble potassium or K2O)
• Guaranteed Analysis
• The name or chemical designation and percentage of each of the active
ingredients

38. Contamination
Human-made inert materials
Must be less than 1/5% by dry weight and less than 13mm in
size.
•Glass
•Metal
•Plastic

39. Permit Application Requirements
Iowa Administrative Code Chapter 105
1. Form 50A
2. Map or Aerial Photograph
3. Design requirements prepared by an Iowa-licensed
professional engineer
4. An operating plan

40. Operating Requirements
• Access to the facility
• Permanent signage
• Materials received must be composted within 24 hours of receipt
• Temperature testing must be done twice a week (131 F)
• Test weekly moisture levels
• Finished compost must be tested for fecal coliform, salmonella,
contaminants, metals (arsenic, cadmium, copper, lead, mercury, nickel,
selenium, zinc). Follow TMECC Standards. (Test Methods for the
Examination of Composting and Compost)
• Operators must be certified by IDNR approved program and renewed every
3 years

41. Record Keeping
Records need to be maintained at the facility for 3 years. This
includes the following:
• Analytical results or testing needs to be recorded on an approved
reporting form
• Compostable materials received annually including types, weights,
and bulking agents
• The tonnage of compost removed annually
• A copy of the plan, permit, annual reports, and storm water pollution
prevention plan

42. Reporting
An annual report for the previous year from July 1 – June 30
must be submitted to the IDNR each year by July 31st.
• Includes tonnage of materials accepted
• Source of material
• Annual capacity of the facility
• Amount of finished compost removed from the facility
• Form found on the IDNR website

43. Inspection and Permitting
• 30 days prior to commencing operation, the IDNR needs to be
notified and will inspect the facility. The notification form can be
found on the IDNR website.
• Solid Waste Composting Facility permits are issued for a period of
three years. Renewal requests must be in writing and filed at least 90
days before the expiration of the current permit. Form 50A can be
found on the IDNR website.
• Facility expansion, changes in facility processes, closures and title
transfers requires prior notification to the IDNR.

44. Financial Assurance
• Facilities that receive more than 5,000 tons of
feedstock annually, (excluding bulking agent) must
obtain and submit a financial assurance instrument.
Monetary funds to properly dispose of any materials in the case
the owner or operator fails to properly close the site within 30
days of permit suspension, termination, revocation, or expiration

45. Exemptions
• Permit-by-Rule – this “exemption” allows composting facilities to
accept less than two tons of food waste per week without a permit
• Yard waste or household organic waste composted and used on the
same premises where originated
• Clean wood waste used as bulking agent (free of coatings and
preservatives)
• Yard waste, household organic waste, and agricultural waste
generated and composted together on the same premises where they
originated

46. Any Questions?