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.

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

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

Creating CompostKey Process Variables

• Feedstocks CarbonNitrogenBulking agents

• Pile moisture• Bulk density• Pile aeration• Pile temperature• Compost curing

Feedstocks – Carbon and Nitrogen

Carbon - Browns Nitrogen – Greens

Photo by Ronny Navarro

United States Composting Council – Compost Operations Training Course, Pomona, CA

Carbon-to-Nitrogen Ratio 30:1

High Carbon - Browns• Corn Stalks75:1• 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

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.

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

Microorganisms have requirements:1. Carbon for energy – microorganisms oxidize carbon2. Nitrogen for growth and reproduction3. Oxygen to aid in decomposition and oxidation of carbon4. Water to maintain activity without causing anaerobic conditions

Illustration from Saba Cooperative

How do microbes obtain energy?

Microbes need to consume feedstocks to:1. Obtain energy2. Obtain nutrients3. As a by-product of microbe metabolism, heat is

generated

Actinomycetes

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%

Moisture Hand Squeeze Test1. Reach into the pile and grab a handful of compost2. Squeeze the material hard, check for drips3. Release your grip and allow material to stay in your hand, smear

some between finger and thumb4. 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.

Moisture – Hand Squeeze Test

Photo by Ronny Navarro

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

Bulk Density is directly related to porosity

Bulk Density TestBucket Drop Method1. Mark the inside of a 5-gallon bucket at 1/3 and 2/3 fill levels2. Tare the bucket and record3. Fill the bucket to the 1/3 line with compost4. Drop the bucket from a height of 6-inches ten times without spilling the

compost5. Fill the bucket with compost to the 2/3 line and repeat step #46. 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.

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%.

Source: Matt Cotton USCC

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

Photo by Ronny Navarro

Compost CuringThe 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.

Compost Calculato

rCustomize your own feedstock recipe using Green Mountain Technologies Compost Calculator

Iowa City Landfill Compost Facility

Cedar Rapids/Linn County Solid Waste Agency

Chamness Technology – Eddyville, Iowa

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

So, how do you start a composting facility at your location?

Three Options1. Compost your own food waste on your own land and use

the compost only on your land = no permit2. Compost outside sources of food waste but accept less

than two tons per week = no permit3. Compost outside sources of food waste accepting more

than two tons per week = need a permit

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

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 liquidsoPonding must be corrected within 48 hours

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

No Infectious Waste is Allowed

•Contaminated sharps•Cultures•Blood or blood products•Pathological waste•Contaminated animal carcasses

Nuisance Laws – odors, dust, noise, litter

Iowa Administrative Code 657.1Whatever 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.

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.

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

ContaminationHuman-made inert materialsMust be less than 1/5% by dry weight and less than 13mm in size.

•Glass•Metal•Plastic

Permit Application RequirementsIowa Administrative Code Chapter 105

1. Form 50A2. Map or Aerial Photograph3. Design requirements prepared by an Iowa-licensed

professional engineer4. An operating plan

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

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

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

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.

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

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

Any Questions?