Reduction of Chemical and Biological Oxygen Demands from Oil Wastes via Oleaginous Fungi: An Attempt to Convert Food by Products to Essential Fatty Acids

Background: The production of waste pollutants has become a major problem for many food and oil industries. However, oil wastes can provide alternative substrates for industry, which could help to solve environmental pollution problems. Furthermore, oil wastes can be used as substrates to produce unsaturated fatty acids, which are important for health. Objectives: The production of fatty acids in fungi using oil wastes and renewable substrates were investigated. Material and Methods: Oil waste sources were obtained from food factories and restaurants (F1, F2, F3, R1, and R2). Cunninghamella echinulata DSM1905 and Rhizopus stolonifer DSM2194 were used to treat the wastes. Changes in lipid and fatty acid contents, biomass, and pH were monitored. Results: C. echinulata produced about 18.4 and 20.1% gamma linolenic acid (GLA) from the R1 and R2 oil wastes, respectively. It also produced 9.3% and 12.4% linolenate from the F2 and F3 wastes. R. stolonifer produced 21% GLA from R1 and 9.3% linolenate from F3. C. echinulata reduced biological oxygen demand (BOD) and chemical oxygen demand (COD) by 67%-74% and 50%-98%, respectively. R. stolonifer reduced BOD by 36%-74% and COD by 10%-78%. Conclusions: This study emphasized the abilities of oleaginous fungi to utilize oil wastes as carbon sources to reduce BOD and COD of the wastes, producing essential fatty acids.