COMPOSTING 101 to 450 Paul Walker

Illinois State University - Normal

• COMPOST DEVELOPMENT

• COMPOST QUALITY

• ON-SIGHT QUALITY DETERMINATION

• POLLUTANT REMOVAL

• EROSION / SEDIMENT CONTROL

Analyze Markets

Prepare Materials

sort, grind, chip, shred

Bulking Agents

Amendments Determine

Recipes

Active Composting

Low Tech High Tech

Curing Screening

Compost Quality

Assessment

“overs”

Product

Refinement

Blending Additives Bagging Storage

COMPOST PROCESS FLOW CHART

Feedstocks

OM + 02 + M.O. Compost + C02 + H2O + N03 + SO4 + heat

RECIPE FORMULATION

• C:N 25:1 to 30:1

• Particle size small but not fine

• Moisture 40 − 65%, 50%

COMPLEX RECIPE VS. SIMPLE MIXTURE

STAGES OF COMPOSTING

Mesophilic Stage 50 °F − 113 °F

Thermophilic Stage 122 °F − 160 °F

PHASES OF AEROBIC

COMPOSTING

• Mesophilic active phase: moderate temps.,

lasts for a few hrs. to a few days

• Thermophilic active phase: high temps.,

lasts from a few days to several weeks

• Mesophilic curing and maturation phase:

moderate to ambient temps., lasts 1-6

months or longer.

WINDROW TEMPERATURE

DYNAMICS

Time (days)

70

40

30

50

0 20 40 60 80 100 120

60

°C

SIMPLIFIED TEMPERATURE

CHANGES IN AN AEROBIC

COMPOST PILE

A B C D 10

20

30

40

50

60

70

Tem

pera

ture

O C

Time

A = mesophilic

B = thermophilic

C = mesophilic

D = maturation

Active

Phase

Curing

Phase

TEMPERATURE

• Optimal temperatures result in faster breakdown of organic materials

• OPTIMAL temperature are in the upper range of mesophilic and lower range of thermophilic microorganism (~45 °C to 55 °C)

• Pathogen reduction (55 °C to 65 °C)

• Excessively high temperatures (> 65 °C) inhibit microbial activity

• Moisture moderates wide swings in temperature

CONDITIONS REQUIRED TO

INACTIVATE WEED SEEDS

AND PATHOGENS

• 150° peak 2 Days

• 130° peak 4 - 6 Days

• 120° peak 5 - 6 Days

COMPOSTING BMP’s

• aerobic, aerobic, aerobic

• monitor temperature

• monitor moisture

• monitor O2 or CO2

THREE IMPORTANT FACTORS

FOR MAKING GOOD

COMPOST PRODUCTS

• Chemical makeup of raw ingredients

• Physical size and shape ->porosity of pile

• Population of organisms involved in the

composting process

• Carbohydrates

• Hemicellulose

• Fats, oils

• Cellulose

• Chitin

• Lignin

CARBON COMPOUNDS

NITROGEN

• Amino Acids

• Proteins

• Sources:

– Green plant tissue

– Animal wastes

VARIABLES IN THE MIX

• Particle size – well graded

• Bulk density

• Moisture 45-65%

• Carbon:Nitrogen 25-30:1

• pH 6.0-7.7

A good recipe mixes feedstocks in

ratios that meet these targets!

PARTICLE SIZE AND POROSITY

• Particle size regulates microbial access to food source, water and oxygen

• Smaller particles have more surface area than large particles; easy access

• HOWEVER, fine particles produce small pores; restricted air flow can lead to anaerobic conditions

• Wood chips create porosity, but carbon is not easily available to microbes

Oxygen Content

• Atmospheric O2 concentration: 20.9%

• Composting is an aerobic process, so we need O2

• O2 levels in compost air should not go < ~6%

• Optimal O2 concentration for composting: 10 - 16%

• O2 >16% to minimize odors

• As pile heats up, more O2 will be consumed

PILE SIZE AND SHAPE

• Pile size will affect O2 content and temperature

– Small piles maintain higher internal O2 concentrations than large piles

– BUT it will not retain heat if the pile is too small

– Large piles retain higher temperatures than small piles

– BUT aeration is insufficient when too large

MOISTURE CONTENT • Optimal range 46% - 65% • Low moisture hinders composting process

because – microbes need water – dry pile will become cool, composting is slowed

down

• Moisture content > 65% means pore spaces filled with water rather than air – insufficient O2 – anaerobic conditions results in hot pile to cools

down – odors due to anaerobic digestion

WINDROW TURNING

FREQUENCY

• First 3 - 5 Days Turn Daily

• Next 3 - 4 Weeks Turn 1 - 3 Times/Week

• Week 5 to End Turn Once/Week (max.)

METHODS OF AEROBIC

COMPOSTING

In-Vessel

Static Pile

Windrow

FRESH COMPOST

• Partially Decomposed

• Not Stable

MATURE COMPOST

• Partially Stabilized

• May Arrest Plant Growth

• Suitable Organic Soil Conditioner

CURED COMPOST

• Highly Stabilized

• Excellent Soil Conditioner

COMPOST ANALYSIS REPORT

IN-FIELD COMPOST

QUALITY INDICATORS

• Crumb structure

• Smell

– odor (NH3)

– aroma (earthy)

• Moisture (Optimum)

IN-FIELD COMPOST ANALYSIS

• Smell Test

• Moisture Test

• Particle Size

• Contaminants

• Solvita Test

• Heat Test

EFFECTIVENESS OF

COMPOST

• Iowa DOT

2 - 4 in. compost blanket runoff H2O 80%

• Research Review

compost berm SS + TSS 66% > silt fence

compost berm SS + TSS 90% > control

EFFECTIVENESS OF

COMPOST (continued)

• Filtrexx Inter. Compared 13 types compost

filter socks

– 6 removed 100% motor oil

– 7 removed 85% motor oil

– motor oil concentration 1,000 to 10,000 mg/L

EFFECTIVENESS OF

COMPOST (continued)

• 2005 Study

– compost higher in elements (metals) than top soil

– compost blankets + berms runoff N 63%

– compost blankets + berms runoff P 32%

– compared to hydro seeding or silt fence

WASHINGTON STATE

RESEARCH

• Compost filter strip P 60%

Cu Pb Zn, SS, COD 63 - 97%

EFFECTIVENESS OF

COMPOST (continued)

• 2004 Study

– MSW compost absorb 85% of rainfall

– control areas absorb 42 - 52% of rainfall

EFFECTIVENESS OF

COMPOST (continued)

• USEPA 1998

– pollutants has degraded in 14 - 60 days

– petroleum hydrocarbons

(gasoline, diesel, oil, grease)

– polynuclear aromatic hydrocarbons

(wood preservatives, refinery wastes)

– pesticides

APPLICATION RATES

Depends on Purpose

• Fertilizer / Soil Amendment

• Runoff Control / Reduction

• Contaminant Capture

• Short Term Erosion Control

• Long Term Plant Establishment

OUTCOMES EXPECTED

• Reduce Runoff

• Increase Storm Water Infiltration

• Filter Pollutants

– Oils

– Elements (metals)

– Pesticides

– Fertilizer

• Increase Plant Growth

ORDER OF SEDIMENT LOSS

low – Low density residential

– Ag land in rotation crops

– Ag land in row crops w. BMP

– Medium density residential

– Freeways

– Ag land in row crops w.o. BMP

high – Areas under development

BMP WHERE COMPOST HELPS

• Erosion Control Blanket

• Filter Strip

• Grass Lined Channel

• Inlet Protection – Sod Filter

• Mulching

• Permanent Vegetation

• Right-of-way Diversion

• Compost Fence

• Temporary Seeding

• Top Soiling

Compost sock (8 - 12 in. dia) replaces

– silt fence (24” high)

– straw bale barrier

– can be dispersed after use

– when mixed with seed can be left in place

COMPOST RULES OF

THUMB

10T:Ac = 1/8 inch layer

80T:Ac = 1 inch layer

Compost absorbs 4 x weight in water

• 1 Part Compost 3 Parts Soil

• 10T Compost:acre

• 40 lbs:100 sq. ft. (cannot see it)

• NOTE: 1 lb. salt:1 sq. ft. = Frosted Look

SOIL AMENDMENT

COMPARATIVE COST OF

COMPOST/STRAW Assumptions

• One bale straw spread 1 in. deep = 111 sq. ft.

• 80T compost:ac = 1 in. deep

• 400 lbs/20% of 1 ton = 1 in. deep = 111 sq. ft.

• Transport and application costs = same

Compost Cost

$ / T 5 10 15 20 25

$ / 111 sq ft 1.00 2.00 3.00 4.00 5.00

$ / straw bale 2.00 to 5.00