Question
I am a researcher in the U.S. and have some projects in third world countries. I work primarily in animal nutrition, and my current project pertains to the use of horticultural byproducts for animal feed. Drying byproducts becomes important when looking at the use of these byproducts for certain species and dried products make feed mixing, handling and storage much easier. One question that comes up routinely is on drying fruit or vegetable or grain byproducts, and the greatest interest is in moderately high moisture-content materials such as citrus pulp and peel, cacao pulp and peel, and byproducts of corn milling. Do you know of a small (1 to 2 tons per day) drying system (equipment) for drying these types of materials? Any pointers you can give me would be greatly appreciated. (R.A.)
Answer
It is not easy to make one recommendation that will fit all circumstances because resources and climate vary so much between third world countries. But the first type of drying to consider is drying in the open sun. Spread the wet product out in a thin layer and stir occasionally. Protect the partially dried product from rain by collecting it in temporary piles. For animal feed it may suitable to dry directly on soil and plan on not collecting everything to minimize the amount of soil collected with the product. Obviously there are some disadvantages with this system, but it requires virtually no capital cost. Heated air dryers, either with solar or perhaps wood require significant investment or energy costs. I doubt low value animal feed is worth the cost of these drying methods. – Jim Thompson