1. Yard Waste Composting

2. Objectives  Describe the most commonly used composting processes.  Explain basic concepts associated with aerobic and anaerobic degradation.  Explain the environmental factors affecting degradation processes.  Explain the operational techniques used to control composting processes.

3. Definition Biological decomposition of organic constituents of wastes under controlled conditions (approximately 70% of MSW is decomposable).

4. Composting Types  Open –Conventional Windrow –Forced Aeration –Static Solids Bed –Forced Aeration –Natural Ventilation  Tower in vessel –Moving Agitated Bed –Moving Packed Bed (Continuous, Intermittent, batch feed)  Horizontal in vessel –Tumbling Solids Bed –Dispersed Flow –Cells in Series –Completely Mixed

5. Compost Rate Controlling Factors  Moisture Content  Carbon:Nitrogen  Temperature  Particle Size  Pile Geometry  Turning frequency

6. Chronological Temperature – Windrows

7. Compost Aeration Air (Oxygen) Heat Rises

8. Effect of Moisture Content on Temperature - Windrows

9. pH of Windrows

10. Compost Turner

13. Windrow Size and Turning Frequency for Leaf Composting a TECHNOLOGYDIMENSIONSTURNING FREQUENCY Minimal12 feet highOnce per year Low6 feet high3-5 times per year Intermediate5-7 feet high 10-14 feet wide Once per week (windrow turning machine) High10 feet high 20 feet wide Forced aeration for the first 2-10 weeks then periodic turnings

14. MATERIALC/N RATIO Activated Sludge6:1 Grass Clippings12-15:1 Mixed Grasses19:1 Sawdust200-500:1 Carbon to Nitrogen Ratios for Various Wastes

15. Compost Maturity  Appearance and Odor  Length of composting period  Reheating temperature  Reduction of Organic Matter  C:N Ratio < 20  Oxygen Uptake Rate  Germination potential

16. Chronological % VS – Windrows

17. Bag Opener

18. Tub Grinder

19. Compost Windrow

20. Compost Turner

21. Compost Monitoring  Oxygen Content  Temperature

22. Compost Screening

23. Finished Compost

24. Sumter County Compost Facility

25. Return to Home Page Last updated August 2007 by Dr. Reinhart