Sand drying beds are a simple application of filtering where gravity carries the liquid down through the sand and the solids form a cake on top. Vacuum filters often use cloth or wire screen to hold the solids as the liquid is drawn through. Presses also use cloth or wire screens to hold the solids as the liquid is pushed through. Drying is used primarily for volume reduction by encouraging the water to evaporate, concentrating the solids. In Ohio, drying systems must be covered to protect them from rainfall, and supplemental heat or forced air is needed to encourage rapid evaporation.
Incineration is an extension of drying.
Manure is converted to an ash requiring application or disposal. Self-sustaining incineration requires a waste of approximately 30percent solids. Wetter manure with lower solids content requires supplemental fuel to continue incineration. Freezing has been demonstrated to improve dewatering in manure, improving settling and filtering. Chemical Treatment Coagulating agents such as ferric chloride, lime, alum, and organic polymers can greatly improve the dewatering characteristics of livestock manure.