Dehydration of Animal Wastes from Livestock Markets

Report Summary: Dehydration of cattle manure from livestock markets is a practical method of reducing the moisture content to a low level. The dried material can be merchandised as a specialty fertilizer. The four dehydrating plants covered in this study used rotary dryers with internal flighting. All dryers were direct fired using natural gas. The dehydrators had a relatively large electrical power demand. The moisture content of the raw material coming into the plant ranged from 38 to 65 percent. Raw material above 60-percent moisture tends to form balls which are extremely difficult to dry. Other problems which must be considered in operating a dehydrating plant are the possibility of fire in the storage areas, the abrasive effects of the dried product on duct work and elevator and auger housings, the effects of dust caused by dried material upon both workers and equipment, and the odor which is generally present at a manure dehydrating plant. The total operating cost for producing a pound of dried product ranges from 1.6 to 2.2 cents. Labor costs account for two-thirds of this total. Other costs include fuel, electricity, and repairs. Generally, the selling price of the dehydrated product only covers costs, and no profit is realized. Dehydration, however, may be the lowest cost method of disposing of large volumes of cattle manure and bedding. The dehydrated product is sold as a low-analysis fertilizer packaged in small units and is retailed through hardware stores, nurseries, and lawn and garden supply stores.