(812b) Evaluation of the Effect of Different Carbon Sources On Lipid Production By Rhodotorula Glutinis From Pulp and Paper Wastewater As Fermentation Media

The potential of utilizing pulp and paper mill wastewater effluents as cultivation media for the sustainable production of microbial lipids as biodiesel feedstock by oleaginous microorganisms is investigated as well as the concurrent COD (chemical oxygen demand) reduction of the recycled wastewater medium. This process could have the potential of reducing treatment costs in paper mill wastewater treatment by utilizing these effluents as growth media for the production of high value bioproducts in addition to treating the effluents prior to environmental discharge. Previous studies have shown that oleaginous microorganisms are able to utilize a wide range of carbon sources singularly or in combination for lipid accumulation under a high carbon-to-nitrogen ratio in the growth medium. This fermentation process for lipid accumulation requires significant amounts of media components such as water and nutrients in addition to high amounts of the carbon source. Therefore, using pulp and paper wastewaters as a media could reduce the cost of using freshwater in media preparations. The biochemical behavior (production of biomass, lipid accumulation, substrate utilization, and fatty acid composition) of oleaginous yeast, Rhodotorula glutinis was studied when grown on pulp and paper wastewater supplemented with glucose, xylose, and glycerol as carbon sources singularly or in mixtures under nitrogen-limited conditions. Since glycerol is the major by-product of biodiesel manufacturing, using it as a carbon source for lipid accumulation may provide an additional benefit of offsetting the cost of biodiesel production. In this study, 20 % (v/v) Rhodotorula glutinis culture was inoculated into the pulp and paper wastewater medium, amended with various carbon sources (glucose, xylose, glycerol, glucose and xylose, glucose and glycerol, and xylose and glycerol), and nutrients (nitrogen, phosphorus) to obtain a high carbon-to-nitrogen ratio of (70:1). The carbon content of the wastewater must be increased due to the lack of carbon and low nutrient sources.  This amended wastewater was used as a fermentation medium for lipid accumulation during the 10 days of cultivation time in a 3-L aerobic batch fermenter. The results indicate that the aforementioned microorganism was able to grow and produce lipids when cultivated in amended pulp and paper wastewater. The fatty acid profile of oleaginous yeast is rich in palmitic, oleic, and linoleic acids and therefore comparable to vegetable oils used to produce biodiesel. The data shows that the microorganism achieved approximately 50% COD removal on amended pulp and paper wastewater.