Kaya, D, and Hung, YT (2020). Treatment of vegetable oil refining wastes. In: “Evolutionary Progress in Science, Technology, Engineering, Arts, and Mathematics (STEAM)”, Wang, Lawrence K. and Tsao, Hung-ping (editors). Volume 2, Number 2, February 2020; 80 pages. Lenox Institute Press, Newtonville, NY, 12128-0405, USA. No. STEAM-VOL2-NUM2-FEB2020; ISBN 978-0-9890870-3-2. ————— ABSTRACT: The common vegetable oils are soybean, sesame, sunflower, corn, canola, and cotton seeds. Their yields, compositions and physical and chemical properties determine their usefulness in various applications aside edible uses. Crude oils obtained by pressing of such vegetable seeds are not usually considered to be edible before the removal of various nonglyceride compounds through operations known as refining. The refining processes remove undesirable materials such as phospholipids, monoacylglycerols, diacylglycerols, free fatty acids, colour and pigments, oxidised materials, etc., but, may also remove valuable minor components such as antioxidants and vitamins (carotenes and tocopherols). The major steps involved in chemical refining include degumming, neutralizing, bleaching, and deodorizing which are the main sources of the effluent. The chapter covers refining steps, its environmental impacts, waste characterization, source reduction, recovery and treatment technologies.