碩士 / 大仁科技大學 / 環境管理研究所 / 106 / The mixotrophic microalgal species are capable to degrade nutrients in wastewater and simultaneously to produce biomass. The objectives of the study were to understand the abilities of the two mixotrophic microalgae, Schroederia sp.、Oocystis sp., on the culture condition, culture harvest, and transesterification of wet biomass for making biodiesel production and reducing wastewater pollution. The mixotrophic microalgae were firstly cultured in batch mode to determine the effect of medium with and without sterilization on microalgal biomass production. Then, the effects of cycle time of culture harvest、N/P ratio of medium, and renewal rate of medium on cell growth and lipid accumulation of Schroederia sp and Oocystis sp using response surface methodology (RSM) experimental design were studied. The optimal culture condition obtained from RSM was also applied to validate the values in photobioreactor experiment. Secondly, the effect of coagulants, ferric chloride and chitin, on microalgae harvesting was studied. Finally, the efficiency of transesterification reaction of wet microalgal biomass was investigated using full factorial design with two-level four factors, namely alkali/acid catalyst amount, reaction temperature, reaction time, and ultrasound power.
The results indicated that no significant difference was found for medium (piggery wastewater) with or without sterilization on biomass productivity, lipid productivity, and nutrient removal from wastewater. The highest biomass production was obtained when cultured with 30% renewal rate of medium, 6 days cultivation time, and 50 mg/mg N/P nutrient ratio. The 120 mg/L.d of biomass productivity and 33.96 mg/L.d of lipid productivity of Schroederia sp. were obtained, while 121.3 mg/L.d of biomass porductivity and 39.4 mg/L.d of lipid productivity for Oocystis sp. were found. These values were in agreement with the results from photobioreactor experiments, 122.5 mg/L.d and 35.33 mg/L.d for Schroederia sp., 129.48 mg/L.d and 43.8 for Oocystis sp., respectively.
For the biomass harvest, the 100% percentage of microalgae harvest was achieved at a 200 mg/L ferric chloride dosage. Potassium permanganate, as a preoxidant, improved the algae harvest by coagulation. With 1 mg/L potassium permanganate preoxidation, similar percentage of biomass harvest were found at 500 mg/L ferric chloride for Oocystis sp., 100 mg/L for Schroederia sp., respectively. Moreover, the 100% percentage of Oocystis sp. harvest was obtained at a 1500 mg/L chitin with 300 mg/L acetic acid assisted, while that of 100 mg/L chitin with 100~300 mg/L acetic acid were for Schroederia sp. The results also indicated that the microalgae regrowth will not be affected by permanganate preoxidation and ferric chloride coagulation.
The highest FAMEs yield of Oocystis sp. (3541.86 mg/L) and was obtained at an acidic catalyst amount of 2% H2SO4/MeOH with the volume of 20 mL, a reaction temperature of 80 °C, a reaction time of 135 min, and ultrasound power of 180 W, while those of 2% H2SO4/MeOH with the volume of 20 mL, a reaction temperature of 60 °C, a reaction time of 135 min, and ultrasound power of 90 W were for Schroederia sp (4419.75 mg/L). For alkali catalysis reaction, the highest FAMEs yield of the two species were obtained at a volume of 20 mL acid with 0.5% of NaOH/MeOH, a 50°C of reaction temperature, a 90 W of ultrasound power, and a 75 min of reaction time.
| Identifer | oai:union.ndltd.org:TW/106TAJ00700005 |
| Date | January 2018 |
| Creators | Zhang, Peng-Sheng, 張蓬昇 |
| Contributors | Chen, Jen-Jeng, 陳振正 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 161 |
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