Hog Waste Disposal by Lagooning

A two-year field investigation and laboratory testing program has proven that a modified anaerobic lagoon can be used successfully for the disposal of confinement-fed hog waste. A loading rate of 275 feeder hogs per acre at an average depth of 5 ft provides for odor-free operation with a minimum of maintenance and a long operational life. The total containment design without an overflow or discharge eliminates the necessity for a receiving stream or secondary treatment but may require a special make-up water source. The system uses single stage anaerobic digestion (liquefaction) combined with a massive heterotrophic growth of algae (Chlorella sp.). A by-product, harvested algae for use as a feed additive, is an indicated possibility. Other included design factors are the chemical constituents and fertilizer values of hog waste. An interesting side-effect is the measurable antibiotic action of the waste caused by a carry-over of antibiotics from the feed. This was found to completely prevent digestion of undiluted waste and caused complete failure of the 5-day BOD test.