The Design And Preliminary Scale-up Of The Reactor Based On Fluent For Biological Treatment Of Refined Soybean Oil Wastewater

Due to the characteristics of less toxic substances and good biodegradability,the refined soybean oil wastewater has been treated by Trichosporon fermentans.In order to realize the further industrial application of this technology,the research and development of high efficiency and low energy consumption wastewater treatment reactor is the key.The development of industrial wastewater treatment reactor needs to be scaled up step by step through small scale test and pilot scale test.The main difficulties in the design of the reactor are to solve the problems of the shear damage of Trichosporon fermentans cells in the reactor and the difficult "oil-in-water" structure in the refined soybean oil wastewater.In order to explore the shear stress tolerance of Trichosporon fermentans,to achieve the initial scale-up of a biological treatment reactor for refined soybean oil wastewater,and to solve the "oil-in-water" structure in wastewater,in this paper,the method of Fluent numerical simulation combined with experiments was applied to study the 5 L stirred reactor in the laboratory,and a 5 L airlift reactor was designed on this basis.A 32 L airlift reactor was built by geometric similarity amplification principle,and the preliminary amplification effect of the airlift reactor was analyzed.Finally,a new type of swirling plate internal member was designed for 32 L airlift reactor.The following results were obtained:The tolerable shear stress of Trichosporon fermentans obtained in a 5 L stirred reactor was3.45 Pascal,and the removals of COD and oil content of refined soybean oil wastewater reached95.81% and 88.09%,respectively.The biomass,oil production and oil content of the Trichosporon fermentans were 9.15 g/L,4.60 g/L and 50.30%,respectively.The optimum height-diameter ratio and diameter ratio of outer cylinder to guide cylinder of the newly designed 5 L airlift reactor were 6.294 and 1.6,respectively,and optimal bottom gap height was 20 mm.The 5 L airlift reactor is amplified by geometric similarity principle to get 32 L airlift reactor.According to the comparative study of the flow field and wastewater treatment effect before and after the reactor amplification,it is found that the volume fraction of gas holdup in the inner cylinder of 5 L and 32 L airlift reactor is 0.35% different,and the maximum liquid velocity is 0.38 m/s different.When the apparent gas velocity was similar and the inoculation amount was the same,the maximum biomass concentration in 5 L and 32 L airlift reactor was 2.26 g/L different,and the maximum COD removal of wastewater was 14.89%different.According to the flow field distribution in the reactor and the results of wastewater biological treatment,it was found that the initial amplification effect not only directly affected the flow field in the reactor,but also further affected the growth of bacteria and wastewater treatment.In the 32 L airlift reactor,the optimal blade elevation and number of the new type cyclone plate were 45° and 8,respectively,and the installation position was 150 mm from the bottom of the guide tube.Compared with the traditional airlift reactor,the wastewater treatment time of the swirl plate airlift reactor was shortened by 8 h,the COD removal increased by 5.10%,and the oil content removal increased by 9.55%.The oil droplets in the "oil-in-water" structure were broken from 16 ?m to 2.5 ?m.