Experimental Study On Microalgae Cultivation Based On Waste Utilization And Co-pyrolysis To Bio-oil

With the rapid development of human civilization,the demand for fossil energy is increasing,and the environmental pollution caused by it is becoming more and more obvious.Microalgae,as one of the main representatives of biomass,has the characteristics of high efficiency of clean and environmental protection,in addition,it also attracted the attention of the majority of experts and scholars in these years.The combined use of microalgae and waste can not only improve the existing environmental problems,but also reduce the economic pressure caused by waste disposal,which is in line with today's sustainable development strategic goals.This article involves a variety of microalgae and waste.The experimental objects are complex and diverse,so it is particularly important to find an applicable method of utilization.Among many energy conversion and utilization methods,high-temperature thermal cracking technology is widely used in biomass thermal conversion experiments because of its easy operation,low emission pollution and short reaction time.On the one hand,this method can be applied to samples such as microalgae,waste glycerin,and kitchen waste water.On the other hand,simple operations are helpful for the comparison and analysis of later reaction products,simplifying the experimental steps,and improve the accuracy of the experimental results.Firstly,this article conducts an experimental analysis of the cultivation of microalgae to study the effects of different LED light wavelengths on the growth of microalgae and the production of biodiesel;secondly,it is found that the process of transferring microalgae to biodiesel will produce a derivative product,waste glycerin,because it is difficult to handle,the waste glycerol and microalgae were co-pyrolyzed,and the pyrolysis products were analyzed.It was found that alcohol and ester-containing compounds can be prepared by one-step pyrolysis.Finally,in order to reduce the cost of microalgae,The use of kitchen waste water in the cultivation and collection of microalgae can not only reduce the input of nutrients and collection costs during the cultivation of microalgae,but also repeatedly put the collected supernatant into the cultivation of microalgae,which saves water resources.The effect of circular cultivation,meanwhile,because the kitchen waste water is added to the co-pyrolysis reaction of microalgae,the quality and the yield of bio-oil are improved.In the light experiment of LEDs on microalgae,Scenedesmus obliquus was used as the cultivation object.It was found that the dry weight of microalgae after blue light cultivation reached 2.19 g L^-1,and the biomass yield reached 0.198 g L^-11 Day^-1,the carbohydrate content reached 31.2%DW,which is the highest value among the experimental samples.Compared with the blank control group,red and blue light showed higher volume lipid productivity with no significant difference,28.1%and 34.7%higher than the control group,respectively.The results show that the combination of red and blue light will have a synergistic effect on the growth of microalgae,which can promote the growth of microalgae S.obliquus,and will increase the accumulation of lipids and fatty acid methyl ester synthesis during the growth process.In the co-pyrolysis experiment of waste glycerol and microalgae,Chlorella vulgaris was used as the experimental object,and it was found that the participation of waste glycerol in pyrolysis can not only increase the yield of bio-oil,but also reduce bio-char formation.According to GCMS analysis of the product,it can be found that the alcohol compounds in pyrolysis bio-oil added with 50%waste glycerol is 50 times higher than that in bio-oil pyrolysis using chlorella vulgaris alone,and the alcohol compounds in bio-oil is38%higher bio-oil which in chlorella vulgaris alone.In the experiment of using kitchen waste water to collect microalgae and co-pyrolysis,S.obliquus was used as the object.Comparing the collection efficiency in the experiment,it was found that the efficiency of the microalgae with an OD₆₈₀ of 3.0 was collected for300 minutes by using kitchen waste water with a concentration of 4%,and the efficiency reached the highest value of 94.09%.The microalgae collected from kitchen waste water will be used for pyrolysis reaction,and the highest bio-oil production yield is calculated to be 55.59%.