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United States Department of Agriculture

Agricultural Research Service

Title: Water Application Method for Composting Cotton Gin Waste

item Thomasson, John

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: June 3, 1996
Publication Date: N/A

Interpretive Summary: Disposing of large quantities of cotton gin waste (CGW) is an economic problem for cotton producers and ginners. The best current approach is spreading it back on farm land. Composting CGW prior to spreading it raw on farm land can alleviate many problems such as infestations of weeds, insects, and disease organisms. Rigorous composting is resource-intensive, so many gins have turned to "unmanaged composting," in which large piles o CGW are created and allowed to decompose on their own. For several reasons, applying water properly to CGW is important for composting. This paper reports tests on the proper application of water to CGW for "umanaged composting." Calculations indicated that setting the initial water flow rate at 17 gallons per bale of picker-harvested cotton would be adequate to bring CGW at virtually any flow rate to an acceptable moisture content to initiate composting. Two systems were operated successfully to inject surfactant into water used to wet CGW. In a small test, surfactant was shown to increase the rate of water uptake by CGW, but in a test at a commercial gin, water uptake was adequate without the use of surfactant. From this paper, a cotton ginner can know the proper water application rate for composting CGW from picker-harvested cotton, and also that surfactant is not required to achieve proper moisture content with the collection systems in common use today.

Technical Abstract: Cotton gins generate large quantities of waste material called cotton gin waste (CGW). Because of environmental concerns, incineration as a disposal method recently became outlawed across the Cotton Belt. Disposing of CGW by other means is costly for many gins. Spreading CGW on farm land has been proposed as the most acceptable method. Composting alleviates most concerns about spreading raw CGW. Bulk density of CGW from seed cotton cleaners was found to be 7.7 lb/ft3 (123 kg/m3). A small composting experiment showed that without mixing the pile, composting was slow compared with past reports. Calculations showed that varying the flow of water used to wet CGW in response to the gin's CGW flow was unnecessary. At two gins with auger-conveyor piling devices, two systems were constructed for injecting surfactant into water to be applied to CGW. One system shut off the water flow automatically when the gin was not running. Both systems worked well. However, though pilot-scale experiments showed that surfactant speeded the uptake of water by CGW, the effect was not evident in a test at a commercial gin. This is assumed to be the result of extended mixing time and extra agitation in the enclosed auger portion in which water mixes with CGW.

Last Modified: 1/26/2015
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