| The bio-energy converted from microalgae has been getting more and moreattentions as it is renewable and greenhouse gas emissions free as the challenges ofsevere environmental pollution and fossil energy consumption. Microalgae isconsidered as the ideal raw material for biodiesel production due to its high energyconversion efficiency and high fat content and fast proliferation. However, algaebiodiesel encountered poor resistance and high culture cost when it developingindustrialization. Thus outstanding algae species should have such characteristics ashigh fat content in and keep a high growth rate in the sewage. Those excellent algae canbe used for wastewater treatment and significantly reduced the cultivation cost.The oil-rich microalgae directional screening method which the target algaespecies both has high oil yield and can also be used for sewage treatment. By this way，five species algae were isolated that can be used for sewage treatment, according to theoil production Performance,3species algae selected from those5species algae that hashigh oil yield.3species algae were determined to genus level. Microalgae PF1wasChlorella sorokiniana， Microalgae PF2was Chlorella sp； Microalgae PF3wasScenedesmus obliquus；Take4microalgae (the2microalgae selected from narural environment, the othersare from laboratory cultural) as objective, artificial wastewater as culture medium, Suchfactors are considered to be changed: the irradiation time, initial pH, COD: TN ratio, theinitial cell density, the amount of plus glucose, The growth characteristics and pollutantsremovaling characteristics were discussed. And then describes the algal cells fat yieldand fat content variations cultured in municipal sewage.The experimental study obtained microalgae PF2and PF3best greaseaccumulation conditions and factors affecting pollutant remova in artificial sewage. Theresults showed that the two microalgae vary greatly for maximum oil yield of cultureconditions, in the light of microalgae PF2time18h, initial pH7.5, the initial amount of25%added algae species, glucose dosage1g/L get the maximum oil yield170.27mg/L;microalgae PF3in illumination time24h, initial pH7.5, COD: TN200:1, glucosedosage of5g/L for maximum fat yield152.30mg/L. In the best conditions for lipidaccumulation, the illumination time18h, initial pH7.5, the initial amount of25%addedalgae species, glucose dosage1g/L when the microalgae PF2pollutant removal capacityof the strongest, in the light of microalgae PF3time18h, pH8.0, COD: TN ratio of200:1glucose1g/L has the highest contaminant removal capacity.Based on artificial wastewater optimal conditions, take municipal wastewater assubstrate cultivation for microalgae PF2and PF3, to study the two microalgae in sterileand non-sterile accumulation of grease in municipal wastewater characteristics and contaminant removal laws. The two microalgae in sterile and non-sterile municipalsewage can grow and both of them showed the strong ability of pollutants remove. Bothof the two microalgae cultivated in sterile sewage group had a higher grease yield thannon-sterile sewage group. The removal of contaminants and oil yield opposite results,both of the two microalgae TP removal efficiency above90%, the COD removal weremore than60%of TN removal efficiency above70%.Took artificial wastewater as substrate for microalgae C.vulgaris and C.solokiniana.Obtained the two microalgae optimal growth conditions and contaminant removalconditions. There is no great difference between the two microalgae culture conditionsto get maximum oil yield. Both in the initial pH was7.5, glucose dosage of1g/L whenthe highest yield and fat were150mg/L or more. Microalgae C.solokiniana growth rateand cell density in the superior C.vulgaris, but microalgae C.vulgaris organic removalcapacity is obviously stronger than C.solokiniana, C.vulgaris and C.solokiniana onCOD removal were81.99%,60.46%, both for TN, TP removal efficiency is not verydifferent, TN removal rate were80%, TP removal rates were above90%.Based on the optimization of environmental conditions, took municipal wastewateras substrate to cultivate microalgae C.solokiniana and C.vulgaris. MicroalgaeC.solokiniana in sterile and non-sterile municipal sewage showed strong biologicalactivity, in sterile sewage algae density of0.65g/L is1.74times the density ofC.vulgaris algae the same conditions, grease yield108.33mg/L is1.91times thanC.vulgaris under the same conditions; microalgae C.solokiniana in raw sewage algaedensity and fat yields were0.50g/L and77.33mg/L respectively, is1.96times and2.29times fo microalgae C.vulgari under the same conditions. Compare the two tomicroalgae remove pollutants in raw sewage situation, in addition to removal of TPlittle difference between the two outside, C.vulgari on COD, TN removal rate was81.99%,75.23%respectively, higher than C.solokiniana removal27.5%and18.96%.Comparing the situation growth rate and contaminant removal efficiency of fourspecies microalgae in municipal sewage, all of them can grow well in the municipalsewage and show a high efficiency of removing pollutants. Compared in artificialsewage, oil-production slightly decrease in the actual municipal wastewater. Excerpt formicroalgae C.vulgaris, the other three species microalgae oil production rate is above77mg/L or more in municipal wastewater. Microalgae cultivation in municipalwastewater provide a new idea for reducing the microalgae cultivation costs and easingmitigate eutrophication... |
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