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In-Vessel Composting

Organic materials are fed into a drum, silo, concrete-lined trench, or similar equipment where the environmental conditionsincluding temperature, moisture, and aerationare closely controlled. The apparatus usually has a mechanism to turn or agitate the material for proper aeration. In-vessel composters vary in size and capacity.
Types of Waste and Waste Generators
In-vessel composting can process large amounts of waste without taking
up as much space as the windrow method. In addition, it can accommodate
virtually any type of organic waste (e.g., meat, animal manure, biosolids,
food scraps). Some in-vessel composters can fit into a school or restaurant
kitchen while others can be as large as a school bus to accommodate large
food processing plants.
Climate or Seasonal Considerations
In-vessel composting can be used year-round in virtually any climate because
the environment is carefully controlled, often by electronic means. This
method can even be used in extremely cold weather if the equipment is
insulated or the processing takes place indoors.
Environmental Concerns
In-vessel composting produces very little odor and minimal leachate.
Requirements
In-vessel composters are expensive and might require technical assistance
to operate properly, but this method uses much less land and manual labor
than windrow composting.
Results
Conversion of organic material to compost can take as little as a few
weeks. Once the compost comes out of the vessel, however, it still requires
a few more weeks or months for the microbial activity to stabilize and
the pile to cool.
For more information on in-vessel and other methods of composting, please see:
- Biosolids Technology Fact Sheet - In-Vessel Composting of Biosolids (PDF) (9 pp, 100K, about PDF)
- California Integrated Waste Management Board's In-Vessel
Compost Technologies for Food Scrap Management

- Cornell
University's Composting Resources

- King County, Washington's Food
Waste Composting (In-Vessel) Bulletin

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