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The Research Of Cultivating Oil-Production Microalgae In Aquaculture Wastewater

Posted on:2012-03-03Degree:MasterType:Thesis
Country:ChinaCandidate:T Y FengFull Text:PDF
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In the research, wastewater from Tilapia nilotica culturing was utilized as the growing medium of Chlorella vulgaris in order to analyze the result of Biological Purification and remediation in effluent, explore the quality and quantity of algal oil and estimate the flexibility of biodiesel production using microalgae.The whole progress is made up by three parts. The first one is to compare the growth attributes of Chlorella vulgaris cultivated in aquaculture wastewater and BG11medium which is regarded as the control group; the second part focuses on the capability of removing nutrition elements, organics from effluent and bioremediation by microalgae in both groups; and the third body mainly demonstrates the content and components of the microalgal oil. The results indicate that Chlorella vulgaris from aquaculture wastewater has a growth rate at2.73×105cell/h which is higher than2.23×105cell/h from the control group, eventually get the concentration at5.765×107cell/mL and4.805×107cell/mL for each. In the experimental group, the morphological characters have changed a lot after a long period of culture, such as the increase of irregularly shaped cells and assembled cells. As a comparison, shape of cells in control group seem round and fine and they all exist as single-cell style. In the entire192h cultivating period, both medium maintain in an alkaline environment(pH8-9). The FIA method was used to analyze the Nitrogen and Phosphate concentration’s variation, and the results show the removal rates of wastewater by Chlorella vulgaris were98.50%N and99.35%P, higher than13.97%N and91.40%P of BG11,respectively. While TOC removal rate from experimental group was22.26%little lower than27.27%in the other group measured via SCWO methodology. And the FTIR results provide that the lipid rate of Chlorella vulgaris produced in waste effluent is32.14%,close to32.99%of the control group. In addition, the lipid rate gained through static hexane lipid extraction is22.68%. Finally,the GC-MS results reveal the components of microalgae oil including Lauric acid(C12:0), Myristic acid(C14:0), Palmitic acid(C16:0), Stearic acid(C18:0), Oleic acid(C18:1), Linolic acid(C18:2), which all fit the standard of biodiesel components.A new type of photobioreactor is also designed and built up for large-scale cultivation of microalgae and biodiesel production. This photobioreactor can be categorized into vertical tubular air-lift type, using LED as light source and air-pump as recirculating power. Though it is still the primitive one that several problems exist and need to be improved, the stability and cost-effective operation of long-period run and continuous production, plus the possibility on the cooperation of recirculating aquaculture system in the future,will potentially promote the efficiency of resource usage and increase the financial benefit.Overall, cultivating oil-production microalgae using aquaculture wastewater could decrease the contamination of the effluent,and also explore a new path of creating new carbon-neutral biofuel. This is an innovative idea of changing waste into valuable and sustainable development.
Keywords/Search Tags:Aquaculture Wastewater, Chlorella vulgaris, Biological Purification, Biodiesel
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