The demand for natural cotton fibers and poly/cotton blend fibers has increased significantly in the last decade. In the United States, approximately 18.5 million bales of cotton were grown in 1994 for fiber production.1
Before cotton fiber can be manufactured from cotton plants, several cleaning steps are required. After the plants have been processed at a cotton gin, the product is distributed to fiber producers. The fiber manufacturer further removes plant material and other debris by dividing and carding the lint. The waste from this process is a mixture of stems, leaves, soils, and lint.
In older fiber manufacturing facilities, seven percent of the cotton product received ends up as waste, while in modern facilities two to three percent of the product becomes waste material. The reduction can be attributed primarily to the development of a fiber reclamation system that can remove lint from the waste. This lint is used in low-grade fiber production.
Because of the differences in the types of manufacturing facilities, it is difficult to determine the quantity of cotton waste generated in North Carolina. It has been estimated that 28,600 tons of cotton waste, not including lint content, were generated by North Carolina fiber manufacturers in 1994.2
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1 Lassiter, Tommy. Presentation at "Cotton Mill Waste Management Seminar." March 16,1995. Rowan County Extension Office
2 Based on discussion by Tommy Lassiter. Assuming 4 million bales consumed in N.C. and using national averages to break up the bales into the following ranges: MID, 63.7 percent with 2.33 percent waste; SLM, 34.7 percent with 3.7 percent waste; and LM, 1.6 percent with 5.93 percent waste. Lint content can be 2 to 4 percent of the total cotton waste.
Most of this waste is currently disposed in sanitary landfills. Assuming an average landfill tipping fee of $35 per ton, more than $1 million is spent on disposal costs alone, and this amount does not account for the cost of handling and shipping or the economic benefits that can be realized from resource recovery.
In recent years, several North Carolina facilities have been proactively locating markets for this waste material. Current uses for waste cotton fibers include composting to produce soil amendment, mulch, top dressing, or potting mix; baling, briquetting, or pelletizing for direct land application; briquetting for fuel sources; and baling, briquetting, or pelletizing for cattle feed.
Textile manufacturers can implement several management techniques to effectively and safely take advantage of these potential markets. The following sections provide information on these successful techniques.
Cotton Waste as Feed Source
Cotton waste from fiber manufacturing facilities typically contains high fiber (above 70 percent) and low protein (4 to 9 percent). Since 1990, the North Carolina State University (NCSU) Cooperative Extension Service has been working with Harriet & Henderson Yarns, Inc., and other textile mills to research the use of cotton waste as a feed source for cows and other domestic animals. This research shows that cotton waste appears to have excellent potential as a substitute for hay as well as a bulking ingredient in higher protein supplements for growing calves and dry brood and lactating cows. Cotton waste, when used as a feed ingredient, improves or maintains animal production.
Regulatory Issues
Despite the successful research, cotton waste from fiber manufacturing facilities has not been officially accepted as a feed ingredient.
Acceptance of a definition of this by-product as a feed source by the American Association of Feed Control Officials (AAFCO) is necessary before it can be legally accepted as a feed. NCSU Extension Ruminant Specialists have provided a definition and research results to the AAFCO for review.
Until the AAFCO takes action and in order to avoid problems with providing this by-product as a feed source, textile manufacturers are cautioned to observe the following guidelines:
- Do not sell cotton waste as feed.
- Do not represent the material as feed.
- Discourage primary contacts from selling the cotton waste as feed.
- Develop a liability release with users of the material.
Arsenic Concerns
Because arsenic-containing defoliants have been used in certain regions of the country, there has been concern over arsenic levels in some cotton waste. Levels of arsenic considered potentially harmful range from 30 to 50 ppm. Although up to 28 ppm have been tested in cotton waste, typical levels will not exceed 2 ppm. To assure complete safety, cotton waste containing above 10 ppm should not be fed to cows. Defoliants containing arsenic have been eliminated in recent years; thus, this concern should not be viable in the near future.
Management Techniques
Facilities should employ several management techniques to facilitate successful partnerships with farmers.
- Keep cotton waste clean of trash such as cigarette stubs, wrappers, etc.
- Reduce the lint content of cotton waste. This material is not palatable to cows, and facilities can benefit from lint recovery through fiber reclamation systems.
- Provide the material in useful form:
- Large bales are sufficient but are difficult for farmers to handle.
- Briquettes are very effective but should not be packed too densely.
- Pellets are the most effective transfer method but require a significant investment.
Those interested in exploring the potential for cotton waste as feed should contact Dr. Matt Poore, Extension Ruminant Nutritionist, at (919) 515-2762 for further information. Note also that current research is underway into the use of poly/cotton waste as a feed source.
Cotton Waste as Soil Additive
Cotton waste has high water retention capacity, sufficient carbon-to-nitrogen ratios, and low heavy metal content. These characteristics make cotton waste viable for direct land application as well as for composting for the production of high-grade mulch, top dressing, potting mix, etc. The NCSU Cooperative Extension Service and several North Carolina textile facilities have successfully developed direct land application and composting operations.
Regulatory Issues
In order for cotton waste to be classified as a soil amendment or fertilizer, the material must be certified by the North Carolina Department of Agriculture, Fertilizer Section. An applicant must provide the following for certification:
- Proof of usefulness.
- Data to substantiate claims.
- Independent laboratory analysis of product.
- TCLP analysis for a variety of metals.
- Complete registration forms and fees.
As basic research has been undertaken previously, there should be little problem with certification. This research has shown heavy metal levels in composted material samples to be below those required by the Fertilizer Section. The contact for further information is Peter Hight, Fertilizer Administrator, at (919) 733-3930.
Additional regulations pertain to land application and composting of this by-product. For information about these regulations, contact Ted Lyon of the North Carolina Department of Environment and Natural Resources (DENR), Division of Solid Waste Management (DSWM), at (919) 733-0692.
Management Techniques
Two techniques for managing cotton waste as a soil additive are direct application and composting.
Direct Application
The several forms in which direct land application can be accomplished provide a variety of benefits:
- Bales. It is easy for the mill to bale the waste, but bales are difficult to apply to the land: the material blows and is awkward to spread.
- Briquettes. Mills typically provide cotton waste as briquettes. This form is being investigated for ease of application.
- Pellets. Although pellets are easy to apply to land and mix well, they are expensive for mills to produce
Contact Ben Chase, Vance/Warren County Extension Agent, at (919) 438-8188 or Ted Lyon, NC Division of Solid Waste Management, at (919) 733-0692 for further information on land application.
Composting
Cotton waste composting has been shown to produce soil amendment, mulch, nutrient supplement, top dressing, and potting mix. Composting of cotton waste typically requires the following materials:
- Storage of waste for 30 days.
- Equipment for turning compost rows.
- Equipment for handling compost.
A productive composting operation requires a significant investment of time and attention, but the revenue produced may provide substantial incentive. Contact Dr. Bob Rubin of the NCSU Cooperative Extension Service at (919) 515-6791 for further information.
Note that some private and local government composting operations are currently seeking this type of material. Cotton sent to composting facilities should be delivered loose, not baled or palletized. For information on composting, contact Ted Lyon of the DSWM at (919) 733-0692 or Scott Mouw, North Carolina Office of Waste Reduction, at (919) 715-6500.
Cotton Waste as Fuel Source
Cotton waste has a energy value of 8,000 to 9,000 Btu/lb. This material has been used successfully in only wood-burning boilers, not coal-burning.
Regulatory Aspects
Facilities considering the use of cotton waste as a fuel by-product need to contact their regional air quality supervisor. For contact information, call the Air Quality Section of the 's Division of Environmental Management at (919) 733-3340. The addition of alternative fuel sources may require modifications to the facility's current air quality permit.
Management Techniques
Although cotton waste will readily burn in any form, briquettes or pellets are easier to handle and burn longer than bales. It is recommended that facilities pursuing this option look into briquetting or pelletizing their cotton waste.
Multiple Management Techniques
Facilities looking to reduce their cotton waste disposal should explore many options for handling this waste as a by-product. The techniques presented in this Fact Sheet may prove sufficient for only a portion of the waste material generated at the facility. Therefore, the most successful management strategy for a facility may be to maintain multiple markets and generate the by-product in the form (briquettes or pellets) most useful for many applications.
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