Cleaning of soapstocks of oil and fat industry enterprises by physico-chemical methods

Abstract

Industrial wastewater from the oil and fat industry contains a variety of pollutants that pass into wastewater during processing of soapstocks: fats and fatty acids and their salts (aqueous soap solutions), glycerin, phosphoglycerides, neutral fat, phosphatides, proteins, carbohydrates dyes (carotene, carotenoids, chlorophyll, etc.), unsaponifiable and waxy substances, salts - sodium sulfate and chloride, mechanical impurities, etc. Soapstocks have a complex and volatile composition, which depends on the nature and properties of its components, the amount of fat-related substances in it. The effect on alkaline reagents and coagulant reagents on co-stocks is proposed and investigated. The obtained results allow to establish rational doses of reagents for effective removal of pollutants from soapstocks. In the studied wastewater, the concentration of organic matter according to the HSC was 40,000 mg / dm3, low pH 2, at which the stability of the state of organic pollutants in the water (no foaming, sedimentation). Calcium carbonate and sodium hydroxide solutions were used as alkalizing reagents. Comparison of the effects obtained under the action of calcium carbonate, compared with the effects obtained with sodium hydroxide, showed 2.4-2.5 times greater efficiency for HSC. The effects of removal of suspended solids and organic substances by HSC at a dose of aluminum sulfate 2 g / dm3 were, respectively, 85.6% and 72% when providing a pH of 5.5 by the action of calcium carbonate. However, it is not possible to remove organic matter to acceptable values ​​when discharged into the city sewer in one stage of purification. Therefore, both after alkalization with calcium carbonate and after coagulation with aluminum sulfate, it is proposed to use the flotation method of phase separation, for example, using air supply through porous materials.