1. Managing Organic Wastes By Composting and Vermicomposting DENR Environmental Education Workshop November 16, 1999 Presenter: Craig Coker, Division of Pollution Prevention & Environmental Assistance

2. PRINCIPLES OF COMPOSTING

3. Principles of Composting What Is Compost? The product resulting from the controlled biological decomposition of organic materials Sanitized through the generation of heat Stabilized to the point where it is beneficial to plant growth Provides humus, nutrients, and trace elements to soils Organic Materials Landfilled wastes (food, wood, textiles, sludges, etc.) Agricultural wastes (plant or animal) Industrial manufacturing byproducts Yard trimmings Seafood processing wastes In short, anything that can be biodegraded

4. Why Compost? > 75% of solid waste in NC is organic 12% of landfilled solid waste in NC in 1998 was food wastes/discards Agricultural wastes  potential for nutrient pollution Yard wastes – banned from landfills in 1993 Compost benefits to soil – 25 lbs N, 13 lbs P (as P 2 O 5 ), and 7 lbs K (as K 2 O) per ton of compost Environmental sustainability

5. The Composting Process Biological decomposition in aerobic environment Decomposition & mineralization by microbes Bacteria, actinomycetes, fungi, protozoans, nematodes Food source – Nitrogen (biodegradable organic matter) Energy source – Carbon (bulking agent) Outputs Heat Water Vapor Carbon Dioxide Nutrients and minerals (compost) Process occurs naturally, but can be accelerated by controlling essential elements

6. Composting Essential Elements Nutrients Carbon/Nitrogen (C/N) – 20:1 to 35:1 Carbon/Phosphorus (C/P) – 100:1 to 150:1 Moisture Content – 50% to 60% (wet basis) Particle Size – ¼” to ¾” optimum Porosity – 35% to 50% pH – 6.5 to 8.0 Oxygen concentration - >5% Temperature – 130 o F. to 150 o F. Time – one to four months

7. Nutrient Balance in Composting C/N ratio – target is 30:1 > 30:1 – not enough food for microbial population < 30:1 – nitrogen lost as ammonia (odors) Sources of N & P - Organic wastes, manures, sludges, etc. Sources of C – wood wastes, woodchips, sawdust Example C/N Ratios: Food waste14 – 16 : 1 Refuse/trash34 –80 : 1 Sewage sludge 5 –16 : 1 Corrugated cardboard 563 : 1 Telephone books 772 : 1 Mixing components needed to optimize C/N ratio

8. Moisture Content Source of nutrients for microbial protein synthesis and growth Optimum water content – 50% to 60% (wet weight basis) < 50% - composting slows due to microbial dessication >60% - compaction, development of anaerobic conditions, putrefaction/fermentation (odors) Water may be needed during mixing, composting Yard wastes – 40 to 60 gallons per cubic yard Typical moisture contents Food wastes70% Manures and sludges72% - 84% Sawdust 19% - 65% Corrugated cardboard 8% Newsprint 3% - 8%

9. Particle Size & Distribution Critical for balancing: Surface area for growth of microbes (biofilm) Adequate porosity for aeration (35% - 50%) Larger particles (> 1”) Lower surface area to mass ratio Particle interior doesn’t compost – lack of oxygen Smaller particles (< 1/8”) Tend to pack and compact Inhibit air flow through pile Optimum size very material specific

10. pH Optimum range 6.5 – 8.0 Bacterial activity dominates Below pH = 6.5 Fungi dominate over bacteria Composting can be inhibited Avoid by keeping O 2 > 5% Above pH – 8.0 Ammonia gas can be generated Microbial populations decline

11. Porosity and Aeration Optimum porosity 35% - 50% > 50% - energy lost is greater than heat produced  lower temperatures in compost pile < 35% - anaerobic conditions (odors) Aeration – controls temperatures, removes moisture and CO 2 and provides oxygen Airflow needs directly proportional to biological activity O2 concentration < 5% - anaerobic conditions

12. Time and Temperature Temperature is key process control factor – monitor closely Optimum temperatures: 130 o F. – 150 o F. Temperatures above 131 o F. (55 o C.) will kill pathogens, fecal coliform & parasites NC Regulations (BYC, small yard waste and on-farm exempt) Temperatures > 131 o F. for 15 days in windrows Temperatures > 131 o F. for 3 days in ASP or invessel Optimum temps achieved by regulating airflow (turning) and/or pile size

13. Time and Temperature, cont.

15. COMPOSTING TECHNOLOGIES

16. Backyard Composting Potential diversion – 400 – 800 lbs/year/household Suitable materials Yard trimmings (leaves, grass, shrubs) Food wastes (produce, coffee grounds, eggshells) Newspaper Unsuitable materials Pet wastes Animal remains (meat, fish, bones, grease, whole eggs, dairy products) Charcoal ashes Invasive weeds and plants (kudzu, ivy, Bermudagrass)

17. Types of BYC Systems

19. Backyard Composting – Easy To Do! Locate in flat area, shielded from sun & wind Add materials in layers (browns/greens) Turn pile after 1 st week, then 2-3 times over next two months

20. Backyard Composting, cont. Can add fresh wastes when turning, but better to start new pile Compost will be ready to use in 4 – 6 months for piles started in Spring 6 – 8 months for piles started in Fall Troubleshooting – see Handout

21. Vermicomposting Home Wastes Vermicompost = worm castings + bedding Nutrient Value - 6600 ppm organic nitrogen, 1300 ppm phosphorus & 1,000 ppm potassium What to feed worms – Vegetable scraps, breads and grains Fruit rinds and peels Tea bags, coffee grounds, coffee filters, etc. What not to feed worms – Meat, fish, cheese or butter Greasy, oily foods Animal wastes

22. Vermicomposting – How To Do It Bin – wooden, plastic or metal with tight- fitting lid 2’ x 3’ x 1’ – good for 2-3 person household Need drainage holes in bottom and air vents on top and sides

23. Vermicomposting – How to do it Add moist drained bedding to worm bin 1” – 2” strips of newspaper/cardboard/leaves/peat moss/sawdust Fill bin with bedding Start with 2 lbs of redworms/lb daily scraps Eisenia foetida or Lumbricus rubellus Bury food scraps under 4 – 6” bedding Rotate burial around bin to prevent overloading Harvest vermicompost in 3 – 6 months

24. Institutional Composting University dining halls Industrial/government cafeterias Current programs in North Carolina UNC – Asheville (Earth Tub) UNC – Charlotte (Earth Tub – next year) NIEHS (Worm Wigwam) DENR/Archdale Cafeteria Sampson Correctional Institution (Worm Wigwam) Brown Creek Correctional (Rotary Drum Composter) Several small schoolroom vermicomposting systems

25. Institutional Composting Worm Wigwam (small) Worm Wigwam (large)

26. Institutional Composting Rotary Drum Earth Tub

27. Institutional Composting Key is efficient source separation of organics Separate collection containers from regular trash Training needed to minimize contaminants (non- compostables like plastics, foils, metals)

28. Commercial Composting Larger-scale commercial and municipal facilities Feedstocks: manures, agricultural wastes (I.e. cotton gin trash), industrial and municipal wastewater treatment sludges, food wastes Technologies used: Windrows Aerated Compost Bins Aerated Static Pile In-Vessel Systems Produced compost sold for $18 - $20/yd 3

29. Overview Technology in Composting Materials Handling Biological Process Optimization Odor Control Capital Cost Increases with technology Operational Costs Decrease with technology Footprint (Area Required) Decreases with technology (usually)

30. Windrow Composting Materials mixed and formed into windrows Windrows 7’ –8’ wide, 5’ – 6’ tall, varying lengths Compost turned and mixed periodically Aeration by natural/passive air movement Composting time : 3 – 6 months

31. Windrow Composting, cont. Equipment Needed Grinder/Shredder Tractor/FEL Windrow Turner tractor-pulled self-propelled Screener One Acre Can Handle 4,000 - 7,000 CY Compost Mix

32. Aerated Compost Bins

33. Aeration through porous floor plates Composting time : 2 - 3 weeks Curing time : 2 months Durable materials of construction Equipment needed : front end loader Vector/vermin control needed with food wastes Capacities : 3 - 4 days food waste + bulking agent per bin

34. Aerated Static Pile Composting Mixed materials built on bed with aeration pipes embedded Aeration by mechanical blowers Composting for 21 days, followed by curing for 30 days Often used in biosolids (sludge) composting

35. Aerated Static Pile Better suited to larger volumes (landscape debris, sludges) Shorter processing time than with windrows May not be suited to wastes that need mixing during composting, like food wastes Difficult to adjust moisture content during composting if needed Odor control difficult with positive aeration Less land area than windrows, still labor intensive

36. In-Vessel Composting More mechanically complex More expensive Smaller footprint (area) Relatively high operations & maintenance costs

37. In-Vessel Composting

38. Commercial Composting in NC Brooks Contractors, Goldston, NC Windrow composting – eggshells, food waste, yard wastes, cardboard McGill Environmental, Rose Hill, NC Aerated static pile – biosolids, industrial food processing residues, furniture wastes Progressive Soil Farms, Welcome, NC Windrow composting – textile wastes, yard wastes City of Hickory, NC In-vessel composting – biosolids, sawdust Mountain Organic Materials, Asheville, NC Aerated compost bins – manures and sawmill wastes Others: Lenoir, Morganton, Shelby

39. Benefits of Compost Utilization

40. Compost Benefits Physical Benefits Improved soil structure, reduced density, increased permeability (less erosion potential) Resists compaction, increased water holding capacity Chemical Benefits Modifies and stabilizes pH Increases cation exchange capacity (enables soils to retain nutrients longer, reduces nutrient leaching) Biological Benefits Provides soil biota – healthier soils Suppresses plant diseases

41. More Compost Benefits Binds heavy metals and other contaminants, reducing leachability and bioabsorption Degrades petroleum contaminants in soils Enhances wetlands restoration by simulating the characteristics of wetland soils Coarser composts used as mulch provide erosion control Can provide filtration and contaminant removal of stormwater pollutants Biofiltration of VOC’s in exhaust gases

42. Typical Compost Characteristics ParameterTypical RangeImportance pH 5.0 –8.5Optimum plant health Soluble Salts1 – 10 dS (mmhos/cm) Phytotoxicity NutrientsN (0.5-2.5%), P (0.2- 2.0%), K (0.3-1.5%) Plant Vitality Need for fertilizers Water Holdng Capacity 75 - 200% dry weight basis Irrigation requirements Bulk Density700 - 1200 lbs/yd 3 Handling/Transportation Moisture Content 30 – 60%Handling/Transportation Organic Matter30 –70%Application Rates Particle Size< 1” screen sizePorosity Trace Elements40CFR503 RegsToxicity StabilityStable – Highly Stable Phytotoxicity

43. Compost Utilization Examples Planting Bed Establishment Apply 3 – 6 yd 3 per 1000 sq. feet Rototill to depth of 6 – 8” Mulch and water after plants installed Turfgrass Establishment Apply 2” – 3” layer of compost to soil Rototill 6 – 8” deep Rake smooth, lay sod or spread seed Apply starter fertilizer and/or water as needed Compost Used For Bedding Mulch 2” – 3” layer installed before mulching with pine bark or hardwood bark mulch

44. Summary Composting is an effective way to manage organic wastes Composting promotes environmental sustainability by converting a waste to a value-added product that improves our environment Composting can be done at home, at school or at work, and by commercial and municipal entities Composting is a mix of the art of the gardener, the science of horticulture, and the discipline of waste engineering… COMPOST HAPPENS!