Utilization Of Rhodotorula Glutinis Cultivation In Cellulosic Ethanal Wastewater For Production Of Microbial Lipid

Microbial lipid is regarded as potential renewable feedstocks for production of biodiesel due to its short production cycle,convenience in scale up and resistance to seasons and sites.However,high cost of microbial lipid using glucoses as substrates limits application and extension.Utilization of Rhodotorula glutinis cultivation in cellulosic ethanol wastewater for production of microbial lipid can not only reduce cost of producing microbial lipid but also utilize concentrated organic wastewater and this is beneficial to economy and environment.This work developed a series of methods for qualitative and quantitative determination of various organic components according to complexity of compounds in cellulosic ethanol wastewater.Results revealed that there were abundant organic carbon sources and organic acids and polysaccharides were main continents which occupied 47.27%and 18.21%in COD of wastewater.Rhodotorula glutinis is able to utilize these organic carbon sources in fermentation for producing lipid but there are many kinds of inhibitors such as furfural,furfuryl alcohol and 5-hydroxymethylfurfural.Optimization of producing microbial lipid using cellulosic ethanol wastewater as substrate was investigated in this work.The highest yield of lipid reached 2.08 g/L of Rhodotorula glutinis cultivated in optimized condition(original wastewater/pure water =1:2,carbohydrate supplement of 40 g/L).Meanwhile,is able to adsorb and utilize some organic contents in cellulosic ethanol wastewater and hence reduce COD and removal of COD,NH4+-N,TN and TP in wastewater reached 83.15%,85.49%,70.52%and 67.46%,respectively.This work also investigated effects of various organic compounds on fermentation of Rhodotorula glutinis for producing lipid.Results showed that four kinds of organic acids were convenient for growth of yeasts and accumulation of lipid;however,three kinds of inhibitors were responsible to reducing the growth and accumulation.Low concentration of acetic acid(<6 g/L)could enhance the growth and accumulation obviously;lactic acid possessed more obvious effects on growth of yeasts and acetic acid and lactic acid were both adsorbed and utilized by Rhodotorula glutinis.Finally,research of advanced treatment and reuse of cellulosic ethanol wastewater was also included in this work.Aerobic and anaerobic fermentation were beneficial to treatment of cellulosic ethanol wastewater and removal of COD was enhanced to 67.55%and effluent COD was reduced to 3000 mg/L;removal of NH4+-N,TN and TP reached 94.17%,48.89%and 90.16%,respectively.In the process of reuse of wastewater,growth of Rhodotorula glutinis and accumulation of microbial lipid were both facilitated.