Gin trash, or as it is called now, cotton gin byproducts, at one time represented a problem to be disposed of, a fire hazard on the gin yard, or an eyesore at the end of ginning season.
As the saying goes, one man’s trash can be another man’s treasure. In recent years, researchers have taken a closer look at gin waste and have found some valuable properties in the burrs, sticks and stems left over after the ginning process.
This series looks at some of the ongoing work that adds value to gin trash.
Cotton gin byproduct (CGB) has not quite lived up to its potential as an eco-friendly, sustainable derivative of the cotton ginning process. But that potential is real.
“I'm a believer in it. I'm optimistic,” says Greg Holt, research leader, USDA-ARS Cotton Production and Processing Research Unit in Lubbock, Texas. “Someone smarter than I am will figure this out. It could be soon, the market and the technology coming together at the right time.”
Cotton gin waste has been a useful byproduct for decades, and researchers have looked into numerous, value-added uses for the burrs, stems, leaves and other organic materials left over after the ginning process.
“We've extruded it, pelletized it for fuel in stoves and boilers; we have made composites, hydro-mulch, other erosion control products (it works very well in that), and a substrate for growing mycelium to make one-use packaging as a polystyrene replacement,” Holt says.
Other uses include MDF (medium-density fiberboards) and other building products used as acoustic materials for sound dampening, among other applications.
Those products, however worthwhile, remained primarily in niche markets or as temporary replacements for something else.
“Overall, it's been hit and miss,” Holt says. “We've had successes that showed promise briefly and then went away. We haven’t found a universal, lasting, overall solution.”
Feed and mulch
CGB as livestock feed has been a consistent byproduct, usually as a replacement during a feed shortage.
“The hydro-mulch was good,” Holt says. “One company manufactured it for 10 or 12 years, but it was like any other new product. You had to train people who were used to dealing with wood and paper. Cotton-based hydro-mulch looked different, even though it performed better, but the market was more about appearance than performance.”
Using plastic module wrap as a substitute for plastic filler suffered a similar fate. “We could get about 30% replacement of the plastic with used module wrap but somebody had to be patient with it. It's not like taking one material out and putting this one in. Systems and people are set up to run a certain way, and when something changes, equipment has to be set up again. Anything associated with change is always a challenge.”
Coming back
Products and processes researchers were looking at some 20 years ago, Holt says, are coming back and could be the catalyst for a more robust market for CGB.
Researchers are looking at processing CGB for eco-friendly soil amendments, biochar, for instance. Holt explains that biochar is created by a thermal chemical process in the absence of oxygen that turns gin waste into a carbon material that acts as a soil amendment and improves moisture retention capacity. Biochar does not break down immediately.
