1998 - Volume #22, Issue #3, Page #41
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"In-Vessel" Composting Catching On Fast
"In-vessel" composting is catching on fast in large part because it's much faster than conventional composting, resulting in stabilization in just three to six days instead of weeks or months, says BW Organics Inc. According to pre-determined menus for each particular material, it allows the site manager to precisely control moisture (which is ideally 40 to 50 percent) temperature (which is ideally 130 to 160 degrees F) and aeration. In-vessel composting can also be done year-around regardless of external ambient temperatures.
Called a "digestor", BW Organics' system consists primarily of a rotating drum constructed of 3/8-in. thick treated metal. It's coated on the outside with 2 in. of spray foam insulation to hold in heat from the composting process. The drums load in one end and unload out the other either manually or by conveyor.
The machine, which is powered by a small electric motor, has proven successful with both dairy and poultry manure as well as a variety of other wastes, such as food and yard waste, in Texas A&M University tests.
For dairies, manure is first pumped from a holding tank into a separator. Freshly separated solid waste averages between 70 and 80 percent moisture and it's dried down to 60 to 65 percent on a pad before loading.
The typical 400-cow dairy produces approximately 2,500 cu. yds. of compost per year, Texas A&M says. At $20 per cu. yd., after deducting variable and fixed costs, sale of compost can net a minimum of $15,000 a year, Texas A&M says.
The system is currently being tested by BW Organics on a big Iowa hog farm as a follow-up to a smaller-scale Texas A&M test.
Five models - two portable and three stationary - are available.
The smaller portable unit, which has a capacity of 2.5 cu. yds., sells for $15,600. The larger, which has capacity of 6 cu. yds., sells for $25,160.
Contact: FARM SHOW Followup, BW Organics Inc., 150 E. Houston, Sulphur Springs, Texas 75482 (ph 903 885-3131; fax 5268).
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