Local bioprospecting mixotrophic Monoraphidium sp. for lipid production and nutrient removal from wastewater
| Autor: | You-Liang Zeng, 曾右良 |
|---|---|
| Rok vydání: | 2014 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 102 Microalgae, which have a higher biomass production and a faster growth rate than other energy crops, has widely recognized as the feedstock for third-generation of biofuels. Many microalgae are exceedingly rich in lipid content for producing biodiesel. However, the accumulation of lipid and increase of cell growth rate depend on diverse factors, including cultivation conditions (photoautotrophic, heterotrophic, mixotrophic and photoheterotrophic cultivation), algal species, and growth environments. The objectives of this study focus firstly on the isolation of some indigenous non-autotrophic microalgae from specific water bodies, such as wastewater treatment plant, subtidal zone, and local fish pond for lipid production. Cell staining and bioprospecting are used for isolating the microalgal algae strains. The microalgae stains are then characterized with the potential biomass production on using wastewater resources and high lipid content of biomass in batch cultures. Secondly, an experimental design methodology and two phase cultivation were used to optimize cultivation conditions for the biomass production of the microalgae isolated and simultaneous nutrient removal from wastewater. Four local microalgae (Monoraphidium sp.、Scenedesmus bicaudatus、Oocystis sp.、Scenedesmus quadricanda) were isolated and then cultured in various concentrations of wastewaters including piggery wastewater, domestic wastewater, and industrial wastewater to understand their biodiesel production and nutrient removal efficiency. The results indicated that Monoraphidium sp. produced highest lipid productivity and nutrient removal efficiency under piggery wastewater cultivation. A two-level full factorial design with four variables was then used to determine the optimal autotrophic growth. The microalga produced highest lipid productivity when culture maintained at 25 °C and with 125 mg/L chemical oxygen demand (COD), 40 mg/L total inorganic nitrogen (TIN), and 2.5 mg/L total phosphorus (TP). The removal efficiencies of COD, TIN, and TP are 97.9 %, 99.7 %, and 97.7 %, respectively. For the four cultivation experiments (photoautotrophic, heterotrophic, mixotrophic and photoheterotrophic), a highest lipid content and lipid productivity was found under mixotrophic cultivation. Both lipid content and lipid productivity increased up to respective 13 % and 72 % as mixotrophic culture with extra-feed of 1 % glucose. Furthermore, biomass productivity and lipid content of Monoraphidium sp. significantly increased in a two phase mixotrophic condition, which culture controlled at 2.5 mg/L TP and then extra-fed 1 % glucose after 7 days cultivation. The specific nutrient removal rate of 17.2 mg/mg COD, 0.41 mg/mg TIN, and 0.04 mg/mg TP were obtained. Monoraphidium sp. is a potential strain for integrating piggery wastewater treatment with microalgal biomass production. Its mixotrophic growth produced biomass practically and economically. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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