Ferric sulfate, ferric chloride, aluminum sulfate, and aluminum chloride are highly effective emulsion breakers for treating waste with oil and grease, as is found in automotive, steel, petrochemical, industrial laundry, tank car and truck washing, diesel shops and food processing operations.  Removal of some heavy metals, such as arsenic, is also possible.  Food processing wastes respond especially well to aluminum chloride, ferric sulfate, and ferric chloride, due to their high mineral acidity and concentration of metal.  Aluminum and iron-based coagulants are compatible with the further processing of these wastes for rendering applications.