Research On High-yield Lipids Microalgae Pilot Scale Industrialization

With the need to reduce carbon emissions, and the dwindling reserves of crude oil,green, clean, renewable biodiesel is an attractive source of energy. Microalgae have gaineda great deal of attention as a potential biodiesel raw material because of their high growthrates and ability to accumulate oil, bind carbon dioxide, and remove contaminants fromwastewater.Nowadays, the cost of microalgae biodiesel was still high, needing for mediaoptimization, large-scale cultivation of microalgae and use the wastewater culturemicroalgae to reduce it cost. And cut down the biodiesel cost.The purpose of this thesis is screening the high-lipid microalgae strains with highbiomass from Wuliangsuhai, Tianjin port of BoHai bay. Discover four oil-rich strains, twofreshwater algae: Scenedesmus quadricanda and Scenedesmus obliquus, two sea algae:marine diatom and Nannochloropsis. Then adjust the best of biomass accumulation,culture condition, scale cultivation, and using the wastewater make it grow to reduce cost.The major results are shown as follows:1. Discover four algal strains：Scenedesmus quadricanda, Scenedesmus obliquus,marine diatom and Nannochloropsis. The initial biomass and lipid content were0.93g/L(17.42%),1.14g/L (15.83%),0.77g/L (21.71%),0.77g/L (23.31%). The fatty acids of thefour microalgae, with a majority as oleic acids and palmitic acids, and contain Linolenic,Linoleic, EPA, DHA. If dissociate those polyunsaturated fatty acids from extracted oil, cancut the cost.2. In order to enhance microalgae biomass and oil content, optimizing the nutrientsthat N, P, Fe, C and Vit B1and using a single factor experiment and L9(34) orthogonaldesign method. The results showed, the optimal concentrations of four kinds of nutrientswas：1) Scenedesmus quadricanda: the sodium nitrate1.5g/L, the monopotassiumphosphate0.4g/L, the chelated iron ions0.0002mol/L and Sodium bicarbonate7.5g/L,reaching the maximum growth rate and lipid content27.32%. 2) Scenedesmus obliquus: the sodium nitrate1.5g/L, the monopotassium phosphate0.3g/L, the chelated iron ions0.0004mol/L and Sodium bicarbonate7.5g/L, reaching themaximum growth rate and lipid content29.25%.3) marine diatom: the sodium nitrate1.0g/L, the monopotassium phosphate0.007g/L,the chelated iron ions0.0004mol/L and Vitmin B10.4μg/L, reaching the maximum growthrate and lipid content29.25%.4) Nannochloropsis: the sodium nitrate0.5g/L, the monopotassium phosphate0.005g/L, the chelated iron ions0.0005mol/L and Vitmin B10.4μg/L, reaching the maximumgrowth rate and lipid content33.88%.3. Making four kinds of progressively expanding photobioreactor, and apply it to theproduction, analysis there biomass and oil content in the different reactor, to determine theoptimal reactor. The race-way photobioreactor was the best photobioreactor, because ofobtained biomass achieving the maximum, and culture conditions being closest to thenatural environment: Scenedesmus quadricanda, Scenedesmus obliquus, marine diatomand Nannochloropsis biomass and lipid cotent were1.19g/L (30.37%),1.39g/L (38.37%),1.17g/L (35.53%) and1.08g/L (35.03%).4. Reduce further costs and the impact on the environment caused by the directdischarge of biogas slurry, and used microalgae cleaning it. Firstly, the biogas slurryneeded to deal with, adding0.7mg/L CPAM keeping the pH9. Then adding MgCl2·6H2Oand KH2PO4·12H2O make solution Mg2+:NH4+:PO43-molar ratio equal1.05:1:1.025, andkeeping pH=9. The pollution load of the remaining NH4+-N, TP, TN, CODCrwas250.14mg/L,26.40mg/L,270.93mg/L,680mg/L. Through grow the algae18d, the pollutionload of the remaining reduce to that NH4+-N, TP, TN, CODCrwas3.40mg/L,0.40mg/L,11mg/L,71mg/L.That conform Secondary effluent of municipal wastewater, and gainingthe algae cells.Through the four microalgae growth conditions, fat content of component evaluation,and Large-scale cultivation laid a theoretical foundation in utilization of high-yield lipidsmicroalgae pilot scale industrialization.