Integrated pollution control in seed oil refining

Abstract

In edible oil refining, the various processes in current use lead to different by-products and/or waste products and they may also cause some form of pollution. The processes are reviewed in this paper and current or possible means of disposal of these by-products/waste products are discussed to highlight the areas requiring most attention. These areas turn out to be gum disposal when the degumming operation is carried out at a stand-alone refinery, and soapstock effluent resulting from the alkali refining process. Other waste products and pollution sources are found to be unimportant or manageable. Accordingly, a major step forward in pollution abatement in seed oil refining can be achieved by making two changes. The first one entails carrying out the degumming operation at the oil mill rather than at the refinery. This should be done in such a way that the degummed oil is amenable to physical refining. The acid refining process is recommended for this degumming step and consequently, acid refined oil with appropriate quality guarantees will then become the article of trade. The second one involves a switch from alkali refining crude or water-degummed oil to the physical refining of acid refined oil. For this latter step, a counter-current process is recommended because of its low stripping steam requirement. Dry condensation of the distillate will further alleviate pollution problems associated with deodorization and physical refining. Finally, some processes, that may contribute to pollution control but that still require development, are mentioned.