Browsing by Author "Chang, Jo-Shu"

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Ability of an alkali-tolerant mutant strain of the microalga Chlorella sp AT1 to capture carbon dioxide for increasing carbon dioxide utilization efficiency
(2017-11-01)
Kuo, Chiu-Mei
;
Lin, Tsung-Hsien
;
Yang, Yi-Chun
;
Zhang, Wen-Xin
;
Lai, Jinn-Tsyy
An alkali-tolerant Chlorella sp. AT1 mutant strain was screened by NTG mutagenesis. The strain grew well in pH 6-11 media, and the optimal pH for growth was 10. The CO2 utilization efficiencies of Chlorella sp. AT1 cultured with intermittent 10% CO2 aeration for 10, 20 and 30 min at 3-h intervals were approximately 80, 42 and 30%, respectively. In alkaline medium (pH = 11) with intermittent 10% CO2 aeration for 30 min at 3-, 6- and 12-h intervals, the medium pH gradually changed to 10, and the biomass productivities of Chlorella sp. AT1 were 0.987, 0.848 and 0.710 g L-1 d(-1), respectively. When Chlorella sp. AT1 was aerated with 10% CO2 intermittently for 30 min at 3-h intervals in semi-continuous cultivation for 21 days, the biomass concentration and biomass productivity were 4.35 g L-1 and 0.726 g L-1 d(-1), respectively. Our results show that CO2 utilization efficiency can be markedly increased by intermittent CO2 aeration and alkaline media as a CO2-capturing strategy for alkali-tolerant microalga cultivation.
An efficient Photobioreactors/Raceway circulating system combined with alkaline-CO2 capturing medium for microalgal cultivation
(2018-10-01)
Kuo, Chiu-Mei
;
Jian, Jhong-Fu
;
Sun, Yu-Ling
;
Lin, Tsung-Hsien
;
Yang, Yi-Chun
High efficiency of microalgal growth and CO2 fixation in a Photobioreactors (PBRs)/Raceway circulating (PsRC) system combined with alkaline-CO2 capturing medium and operation was established and investigated. Compared with a pH 6 medium, the average biomass productivity of Chlorella sp. AT1 cultured in a pH 11 medium at 2L min(-1) circulation rate for 7 days increased by about 2-fold to 0.346g L-1 d(-1). The maximum amount of CO2 fixation and CO2 utilization efficiency of Chlorella sp. AT1 could be obtained at a PBRs to Raceway ratio of 1:10 in an indoor-simulated PsRC system. A similar result was also shown in an outdoor PsRC system with a 10-ton scale for microalgal cultivation. Under the appropriate circulation rate, the stable growth performance of Chlorella sp. AT1 cultured by long-term semi-continuous operation in the 10-ton outdoor PsRC system was observed, and the total amount of CO2 fixation was approximately 1.2kg d(-1) with 50% CO2 utilization efficiency.
Bioethanol production from acid pretreated microalgal hydrolysate using microwave-assisted heating wet torrefaction
(2020-11-01)
Yu, Kai Ling
;
Chen, Wei-Hsin
;
Sheen, Herng-Kuang
;
Chang, Jo-Shu
;
Lin, Chih-Sheng
This study focused on the bioethanol production from the co-production of solid biochar and liquid hydrolysate under microwave-assisted heating wet torrefaction towards a sustainable green technology. The two indigenous microalgal biomass undergone dilute acid pretreatment using wet torrefaction to produce microalgal hydrolysates and biochar at operating conditions of 160-170 degrees C with holding times of 5-10 min. The hydrolysates were utilized for fermentation with the yeast Saccharomyces cerevisiae at 29 degrees C in a dark condition at a non-agitation state for 120 h. The concentrations of total reducing sugar, reducing sugar by-product, and bioethanol in the hydrolysates were determined. The carbohydrate-rich microalga C. vulgaris ESP-31 showed a good performance in bioethanol production. Microalgal hydrolysate obtained after the pretreatment consisted of a total reducing sugar with the highest concentration of 98.11 g/L. The formation of by-product 5-hydroxymethyl-2-furaldehyde (5 HMF), which might act as the fermentation inhibitor that led to the low ethanol yield, was also analyzed. The highest ethanol yield achieved was 7.61% with a maximum experimental conversion probability of 95.22%. This study has demonstrated the feasible bioethanol production from microalgal hydrolysate through microwave-assisted heating wet torrefaction using dilute acids and the optimization of bioethanol production can be carried out for better performance in the future study.
Characterization of a heat-tolerant Chlorella sp GD mutant with enhanced photosynthetic CO2 fixation efficiency and its implication as lactic acid
(2017-09-12)
Lee, Tse-Min
;
Tseng, Yu-Fei
;
Cheng, Chieh-Lun
;
Chen, Yi-Chuan
;
Lin, Chih-Sheng
Background: Fermentative production of lactic acid from algae-based carbohydrates devoid of lignin has attracted great attention for its potential as a suitable alternative substrate compared to lignocellulosic biomass. Results: A Chlorella sp. GD mutant with enhanced thermo-tolerance was obtained by mutagenesis using N-methyl-N'-nitro-N-nitrosoguanidine to overcome outdoor high-temperature inhibition and it was used as a feedstock for fermentative lactic acid production. The indoor experiments showed that biomass, reducing sugar content, photosynthetic O-2 evolution rate, photosystem II activity (F-v/F-m and F-v'/F-m'), and chlorophyll content increased as temperature, light intensity, and CO2 concentration increased. The mutant showed similar DIC affinity and initial slope of photosynthetic light response curve (a) as that of the wild type but had higher dissolved inorganic carbon (DIC) utilization capacity and maximum photosynthesis rate (P-max). Moreover, the PSII activity (F-v'/F-m') in the mutant remained normal without acclimation process after being transferred to photobioreactor. This suggests that efficient utilization of incident high light and enhanced carbon fixation with its subsequent flux to carbohydrates accumulation in the mutant contributes to higher sugar and biomass productivity under enriched CO2 condition. The mutant was cultured outdoors in a photobioreactor with 6% CO2 aeration in hot summer season in southern Taiwan. The harvested biomass was subjected to separate hydrolysis and fermentation (SHF) for lactic acid production with carbohydrate concentration equivalent to 20 g/L glucose using the lactic acid-producing bacterium Lactobacillus plantarum 23. The conversion rate and yield of lactic acid were 80% and 0.43 g/g Chlorella biomass, respectively. Conclusions: These results demonstrated that the thermo-tolerant Chlorella mutant with high photosynthetic efficiency and biomass productivity under hot outdoor condition is an efficient fermentative feedstock for large-scale lactic acid production.
Cultivation of Chlorella sp GD using piggery wastewater for biomass and lipid production
(2015-10-01)
Kuo, Chiu-Mei
;
Chen, Tsai-Yu
;
Lin, Tsung-Hsien
;
Kao, Chien-Ya
;
Lai, Jinn-Tsyy
The development of a culture system for Chlorella sp. GD to efficiently produce biomass and oil for biodiesel production was investigated. Chlorella sp. GD was cultivated with 0%, 25%, 50%, 75% and 100% piggery wastewater (diluted by medium) at 300 mu mol m(-2) s(-1), a 2% CO2 aeration rate of 0.2 vvm and 26 +/- 1 degrees C; after a 10-day culture in batch cultures, the maximum specific growth rate and biomass productivity of the microalga obtained in 100% piggery wastewater were 0.839 d(-1) and 0.681 g L-1 d(-1), respectively. The highest lipid content and lipid productivity were 29.3% and 0.155 g L-1 d(-1) at 25% wastewater, respectively. In semi-continuous cultures, the biomass and lipid productivities with 25-75% wastewater ratios were greater than 0.852 and 0.128 g L-1 d(-1), respectively. These results show that Chlorella sp. GD grows efficiently in piggery wastewater, and that a stable growth performance was achieved for long-term microalgal cultivation in a semi-continuous culture. (C) 2015 Elsevier Ltd. All rights reserved.
Ferrofluid-assisted rapid and directional harvesting of marine microalgal Chlorella sp used for biodiesel production
(2017-11-01)
Ho, Shih-Hsin
;
Chiu, Sheng-Yi
;
Kao, Chien-Ya
;
Chen, Tsai-Yu
;
Chang, Yu-Bin
In this work, a novel harvesting strategy using ferrofluids coupled with flocculation as a magnetic directional harvesting system was developed, providing a fast and easy way to effectively collect microalgae with no further modifications made to the ferrofluids. With a ferrofluid dosage of 25 mg L-1, a high harvesting efficiency of 95-100% was achieved within 1 min. In addition, we successfully performed a wastewater recycling strategy coupled with a microalgal ferrofluid-harvesting dynamic flow-through system to harvest biomass of Chlorella sp. MTF-7 which could achieve over 80% of the maximum level after three repeated recycling cultivations. This work demonstrated the use of an integrated microalgal ferrofluid-harvesting dynamic flow-through system to develop a simple and effective strategy to enhance microalgal harvesting efficiency, along with wastewater recycling, in a marine microalgal Chlorella sp. MTF-7. (C) 2017 Elsevier Ltd. All rights reserved.
Microalgal biomass production and on-site bioremediation of carbon dioxide, nitrogen oxide and sulfur dioxide from flue gas using Chlorella sp cultures
(2011-10-01)
Chiu, Sheng-Yi
;
Kao, Chien-Ya
;
Huang, Tzu-Ting
;
Lin, Chia-Jung
;
Ong, Seow-Chin
The growth and on-site bioremediation potential of an isolated thermal- and CO(2)-tolerant mutant strain. Chlorella sp. MTF-7, were investigated. The Chlorella sp. MTF-7 cultures were directly aerated with the flue. gas generated from coke oven of a steel plant. The biomass concentration, growth rate and lipid content of Chlorella sp. MTF-7 cultured in an outdoor 50-L photobioreactor for 6 days was 2.87 g L(-1) (with an initial culture biomass concentration of 0.75 g L(-1)), 0.52 g L(-1) d(-1) and 25.2%, respectively. By the operation with intermittent flue gas aeration in a double-set photobioreactor system, average efficiency of CO(2) removal from the flue gas could reach to 60%, and NO and SO(2) removal efficiency was maintained at approximately 70% and 50%, respectively. Our results demonstrate that flue gas from coke oven could be directly introduced into Chlorella sp. MTF-7 cultures to potentially produce algal biomass and efficiently capture CO(2), NO and SO(2) from flue gas. (C) 2011 Elsevier Ltd. All rights reserved.
Production of microalgal biochar and reducing sugar using wet torrefaction with microwave-assisted heating and acid hydrolysis pretreatment
(2020-08-01)
Yu, Kai Ling
;
Chen, Wei-Hsin
;
Sheen, Herng-Kuang
;
Chang, Jo-Shu
;
Lin, Chih-Sheng
This study employed the microwave-assisted acid hydrolysis pretreatment using wet torrefaction on two indigenous microalgae, Chlorella vulgaris ESP-31 and Chlorella sp. GD with different biomass composition to investigate the yields of solid biochar and total reducing sugar in the liquid hydrolysate. Operating conditions at low temperatures (160, 170 degrees C) with short holding time (5, 10 min) under several concentrations of diluted acid medium (0, 0.1 and 0.2 M) were carried out to investigate the torrefaction severity effects towards the properties of the solid and liquid products. The highest biochar yields of 54.5% and 74.6% are obtained from C. vulgaris ESP-31 and Chlorella sp. GD, respectively under the wet torrefaction conditions with an improvement in the properties for fuel and value-added environmental application. The highest total reducing sugar concentration of 98.11 g/L and 12.08 g/L are obtained in C. vulgaris ESP-31 and Chlorella sp. GD liquid hydrolysates, respectively after acid hydrolysis pretreatment. With the co-production of high total reducing sugar in the liquid hydrolysate that can be utilized for bioethanol production and solid biochar as another value-added product, the acid hydrolysis pretreatment using wet torrefaction can be one of the conversion technologies towards the application of renewable energy production. (C) 2020 Elsevier Ltd. All rights reserved.
Simultaneous microalgal biomass production and CO2 fixation by cultivating Chlorella sp GD with aquaculture wastewater and boiler flue gas
(2016-12)
Kuo, Chiu-Mei
;
Jian, Jhong-Fu
;
Lin, Tsung-Hsien
;
Chang, Yu-Bin
;
Wan, Xin-Hua
A microalgal strain, Chlorella sp. GD, cultivated in aquaculture wastewater (AW) aerated with boiler flue gas, was investigated. When AW from a grouper fish farm was supplemented with additional nutrients, the microalgal biomass productivity after 7 days of culture was 0.794 g L-1 d(-1). CO2 fixation efficiencies of the microalgal strains aerated with 0.05, 0.1, 0.2, and 0.3 vvm of boiler flue gas (containing approximately 8% CO2) were 53, 51, 38, and 30%, respectively. When the microalgal strain was cultured with boiler flue gas in nutrient-added AW, biomass productivity increased to 0.892 g L-1 d(-1). In semi-continuous cultures, average biomass productivities of the microalgal strain in 2-day, 3-day, and 4-day replacement cultures were 1.296, 0.985, and 0.944 g L-1 d(-1), respectively. These results demonstrate the potential of using Chlorella sp. GD cultivations in AW aerated with boiler flue gas for reusing water resources, reducing CO2 emission, and producing microalgal biomass. (C) 2016 Elsevier Ltd. All rights reserved.
Utilization of carbon dioxide in industrial flue gases for the cultivation of microalga Chlorella sp.
(2014-08-01)
Kao, Chien-Ya
;
Chen, Tsai-Yu
;
Chang, Yu-Bin
;
Chiu, Tzai-Wen
;
Lin, Hsiun-Yu
The biomass and lipid productivity of Chlorella sp. MTF-15 cultivated using aeration with flue gases from a coke oven, hot stove or power plant in a steel plant of the China Steel Corporation in Taiwan were investigated. Using the flue gas from the coke oven, hot stove or power plant for cultivation, the microalgal strain obtained a maximum specific growth rate and lipid production of (0.827 d(-1), 0.688 g L-1), (0.762 d(-1), 0.961 g L-1), and (0.728 d(-1), 0.792 g L-1), respectively. This study demonstrated that Chlorella sp. MTF-15 could efficiently utilize the CO2, NOX and SO2 present in the different flue gases. The results also showed that the growth potential, lipid production and fatty acid composition of the microalgal strain were dependent on the composition of the flue gas and on the operating strategy deployed. (C) 2014 Elsevier Ltd. All rights reserved.