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Production of biodiesel by mixed culture of oleaginous yeast Rhodosporidium toruloides and microalga Chlorella pyrenoidosa from wastewater

English Abstract

For the purpose of environmentally sustainable development, the recovery of resource or energy from wastes has attracted worldwide attention these days. The wastewater generated from food industries is more difficult to treat than the domestic wastewater due to their high organic loads. This study is to explore the possibility of developing a pre-treatment process which could produce microbial lipid that could be converted to biodiesel by recovering nutrients from wastewater while simultaneously removing part of organic matters through cultivating oleaginous microorganisms. The lipid productivity by oleaginous yeast Rhodosporidium toruloides was studied using wastewater from domestic wastewater treatment plant, milk candy and biscuit factory, beer brewery, and rice wine distillery, at different temperatures, inoculum sizes, and incubation periods under sterile conditions. Chemical oxygen demand (COD) removal efficiency, biomass production, and lipid yield were analyzed. Both rice wine distillery wastewater and milk candy wastewater showed good potential in lipid production. To improve the process of producing lipid from real distillery and domestic mixed wastewater by oleaginous yeast R. toruloides in the presence of indigenous microorganisms, the effect of initial soluble chemical oxygen demand (SCOD) and initial cell density was investigated under non-sterile conditions. The results shown that when initial cell density was increased to 2-5 x 107 cells/mL, both lipid productivity and removal efficiencies could be enhanced in a shorter incubation time. The process was then further improved by inoculating microalga Chlorella pyrenoidosa with yeast after the growth of yeast increased the pH of real distillery and domestic mixed wastewater from 3.7 to about 7 with higher lipid production in mixed culture of yeast and microalga samples than pure culture of yeast or microalga samples. A direct transesterification process from fresh living yeast biomass via microwave irradiation was developed. The energy consumption assessment showed that microwave assisted method could reduce the energy consumption significantly since it was applicable to wet biomass and save the lots of energy consumed during dewatering process though solvent demand was higher. Overall, the methods and technologies presented here can be good candidates for bioenergy recovery from wastewater.

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Ling, Jia Yin,


Faculty of Science and Technology


Department of Civil and Environmental Engineering




Water treatment plant residuals -- Purification

Waste products as fuel

Water -- Purification

Biochemical engineering


Shim, Hojae

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