Utilization of Biosolids for Pasture Fertilization

Biosolids are solid, semi-solid, or liquid materials resulting from the treatment of domestic sewage sludge. The term “biosolids” was introduced by the wastewater treatment industry in the early 1990’s and has been adopted by the United States Environmental Protection Agency (U.S. EPA) to distinguish high quality, treated sewage sludge from raw sewage sludge and from sewage sludge containing large amounts of pollutants. Raw sewage sludge must be processed to meet U.S. EPA criteria before they may be called biosolids. Unlike other organic materials such as animal manure, biosolids are subjected to strict regulations that control their use and disposal. Physical, chemical, and biological processes are often employed to reduce pathogens levels, odor, and vector attraction of domestic wastewater. Anaerobic and aerobic digestion, alkaline stabilization, dewatering, composting, and heat-drying are some of the treatments that biosolids may undergo before they can be land applied. The type and extent of the treatment affect biosolids composition and nutrient availability; thus biosolids should be analyzed prior to application to determine adequate application method and rates.