| 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 tons
per 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. |
