Thermal drying takes biosolids cake to a minimum total solids content of 90 percent, using various technologies. The resulting product is a dry Class A granule. Some equipment has a primary goal of removing water from the biosolids for landfilling, land application, and/or burning as a fuel. The primary advantage to such a drying process is reduced hauling volume. Other drying technologies yield a dry, hard, homogeneous product that is considered to be a marketable fertilizer or fertilizer component. Some installations produce uniform-size biosolids pellets and coat them with mineral oil. That product can be readily blended with commercial fertilizer products and spread using conventional equipment.
