Biovalorization of vegetable oil refinery wastewater into value‐added compounds by Yarrowia lipolytica

BACKGROUND Vegetable oil refinery wastewater (VORW) is an environmental pollutant in less developed countries which annually produce 75% of vegetable oils worldwide. Microbial oils from low‐cost substrates are of growing importance for the production of renewable biofuel feedstocks, and food and feed supplements. In the current study, VORW was used as a cheap substrate to produce added‐value compounds including lipase, microbial oil and lipid‐rich biomass using Yarrowia lipolytica. The chemical oxygen demand (COD) reduction of the wastewater was studied after fermentation. RESULTS The maximum microbial oil concentration and lipase activity were 2.68 g L−1 and 8 U mL−1 after 48 h of inoculation. The microbial oil production increased from 2.86 g L−1 to 7.74 g L−1 after optimization by response surface methodology. Using optimized medium, 11 g L−1 microbial oil and 18.3 g L−1 biomass were obtained in the bioreactor culture. The amount of unsaturated fatty acids (FAs) reached ≤63% in the resulting microbial oil with a suitable FA profile for the production of lipid‐rich biomass. The biomass of Y. lipolytica has 60% lipid content and a significant amount of essential FAs which makes it as a proper feed supplement. The COD level of the wastewater decreased by 80% after 20 h. CONCLUSION VORW can be used as a promising substrate for the sustainable production of microbial oil and lipid‐rich biomass with useful FAs by Y. lipolytica. This process also can simultaneously reduce environmental pollution of wastewater in a safe and eco‐friendly way.