Solid Waste Disposal
Spent filter cake, consisting of bleaching earth and filter aid, may contain 25-100% soy oil (Smallwood 1995). Because the oil has nutritional value and the clay is inert, it is used as a processing aid in soy meal, otherwise the filter cake can be disposed in landfills. Handling used bleaching clay can be dangerous because oxidation products from the adsorbed soy oil could spontaneously combust.
Used hydrogenation catalyst poses a disposal problem and is best removed by and recycled by professional metal processors (Smallwood 1995). The cost of disposal is determined by the metal content of the catalyst. The market price of the metal catalyst determines the cost and economic feasibility of reclamation.