| Criterion: | Aerated Static Piles: |
ACS Composting: |
| Mixing & Blending |
Thorough mixing and blending of materials does not occur. | Thorough mixing and blending occurs enabling interaction of carbon and nitrogen atoms. |
| Aeration | Airflow can form channels leaving anaerobic areas. | All materials turned have access to oxygen while passing over drum. |
| Temperature Control |
If positive pressure is used to vent heat, it may be difficult to meet temp requirements near the pipes. |
All materials in row have access to required thermophilic cycle for pathogen and weed seed destruction. |
| Watering | Added to windrow perimeter. Not consistent throughout. | Each particle is watered for equal moisturization throughout the row. |
| Odors | Biofilters are frequently utilized to manage odors. | Odors in windrows should disappear after 2-3 days. |
| Compost Quality |
Typically defines quality in terms of the absence of pathogens. | Defines quality in terms of what it does for the soil and plant. Complete laboratory comparisons are encouraged. |
| Profitability | Such facilities are often government operated, as private entities have difficulty profiting. Compost is often given away. Income is driven by tipping fees. |
Compost is often sold at from two to four times the cost per ton to produce. Income from compost sales can be a significant profit stream because of the product quality. |
| Startup & Annual Costs |
Capital costs for an enclosed facility processing approximately 5,000 tonsper year of wood and yard waste is approximately 2 million to 5 million dollars. Capital costs, not including land, will be decreased by building costs ($75 sq. ft.) in an open facility. Annual operating costs range from $10 to $70 per ton. Aeration pipes may require disposal or recycling.* | Capital costs for an enclosed facility with similar tonnage would be in the $400,000 range. Open air facility would be significantly less. |
