title: Long-term production of bioethanol in repeated-batch fermentation of microalgal biomass using immobilized Saccharomyces cerevisiae.
abstract: Separate hydrolysis fermentation (SHF) and simultaneous saccharification fermentation (SSF) processes were studied for bioethanol production from microalgal biomass. SSF was selected as an efficient process to enhance the bioethanol yield through repeated-batches using immobilized yeast cells. Combined sonication and enzymatic hydrolysis of Chlamydomonas mexicana generated 10.5 and 8.48g/L of ethanol in SSF and SHF, respectively. Yeast utilized maximum portion of total reducing sugar (TRS) reaching a consumption efficiency of 91-98%. A bioethanol yield of 0.5g/g (88.2% of theoretical yield) and volumetric productivity of 0.22g/L/h was obtained after 48h of SSF. Immobilized yeast cells enabled repetitive production of ethanol for 7 cycles displaying a fermentation efficiency up to 79% for five consecutive cycles. The maximum ethanol production was 9.7g/L in 2nd-4th cycles. A total energy recovery of 85.81% was achieved from microalgal biomass in the form of bioethanol. Repeated-batch SSF demonstrated the possibility of cost-effective bioethanol production.
authors.affiliation: Department of Earth Resources and Environmental Engineering, Hanyang University, Seoul 133-791, South Korea.
authors.forename: Marwa M
authors.initials: MM
authors.lastname: El-Dalatony
authors.affiliation: Department of Earth Resources and Environmental Engineering, Hanyang University, Seoul 133-791, South Korea.
authors.forename: Mayur B
authors.initials: MB
authors.lastname: Kurade
authors.affiliation: Department of Environmental Biotechnology, City of Scientific Research and Technology Applications, New Borg El Arab City, Alexandria 21934, Egypt.
authors.forename: Reda A I
authors.initials: RAI
authors.lastname: Abou-Shanab
authors.affiliation: Department of Earth Resources and Environmental Engineering, Hanyang University, Seoul 133-791, South Korea.
authors.forename: Hoo
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Earth Resources and Environmental Engineering, Hanyang University, Seoul 133-791, South Korea.
authors.forename: El-Sayed
authors.initials: ES
authors.lastname: Salama
authors.affiliation: Department of Earth Resources and Environmental Engineering, Hanyang University, Seoul 133-791, South Korea. Electronic address: bhjeon@hanyang.ac.kr.
authors.forename: Byong-Hun
authors.initials: BH
authors.lastname: Jeon
mesh_terms: D018533:Biomass; D018914:Cells, Immobilized; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D058086:Microalgae; D012441:Saccharomyces cerevisiae / Q000378:metabolism*
chemical_list: D000431:Ethanol
keywords: Bioethanol; Energy recovery; Immobilized yeast; Microalgae; Repeated batch fermentation; Saccharification