2004 Volume 53 Issue 5 Pages 221-229
The amount of used edible oil generated in Japan annually is presumed to be some hundred thousand tons. Half of it is rather easy to recover because it comes from food manufacturing industries, supermarkets, restaurants, and the like. Recovered oil of good quality is diverted for use as a fatty acid source or in the production of feed oil, paint, ink, fuel oil, soap, or other products, but the rest is burned or discarded. Stiff competition between the price of good-grade oil and the cost of refining low-grade oil is the principal reason for the insufficient reuse of recovered oil. The burning or discarding of large amounts of recovered oil in spite of a relatively low level of deterioration adversely affects the environment and promotes Japan’s dependency on imports. In this study, safe and inexpensive methods for refining used edible oil (Gardner color 11) to non-food industry oil (Gardner color<7) with possibly a small amount of factory waste were investigated. Refined oil with Gardner color 6 was prepared by a process consisting of filtration on an adsorbent and barium hydroxide or sodium hydroxide refinement. Barium hydroxide-refined oil was further bleached by hydrogen peroxide to obtain heat-stable reclaimed oil of Gardner color 3.
