Team:Worldshaper-Nanjing/Implementation
General process
The purpose of our project is producing biodiesel by using yeast to ferment substandard grain. By using this technology, besides solving the problem of substandard grain, people may also get a kind of stable and reproducible resource that can be used for most engines that need diesel oil. We may collaborate with grain purchasing and storage enterprises as well as government who have to face the substandard grain problems by providing this technology, and supply the biodiesel to customers, such as biofuel stations.
By using this technology, biodiesel can be produced in specific factory directly by stable reactions. The whole project, from raw materials collection to supplying biodiesel to fuel station, included 11 steps shown in Fig.1.
- Fig.1 The whole process of biodiesel production
1. Collect raw materials. From the results of human practices, we have learned that substandard grains are governed by unified supervision and deployment by the food department. Therefore, we can cooperate with government departments to collect the stored materials, and transport these grains to biodiesel manufacture factory and store them in factory’s storage.
2. Since we use substandard grain as the raw materials, which may mildewed or be polluted, these grain are required to be sterilized and cleaned before next process, including removing shell and separation from impurities, such as stones and sticks. [1]
3. Mill the grain to smaller particles. The raw materials will have larger surface area and can be fermented easier. Based on whether the grain is first soaked in water to fractionate it into its individual components, this step is categorized into two methods: wet milling and dry milling, and both them have their advantages and disadvantages [1-2]
4. Cooking and liquefaction. Heat and cook the grain particles at high temperature. With time the tightly bound grain starch becomes soft and spongy and becomes amenable to efficient enzymatic digestion.[1] According to the formula, use cooked grain particles and corresponding ingredients, such as (NH4)2SO4, KH2PO4, Na2HPO4, MgSO4, CaCl2, FeCl3, etc., to prepare the fermentation medium in the ingredients tank.
5. Fermentation. Add the medium into the fermentation tank, sterilize and control fermentation conditions, such as pressure, temperature, PH, etc. then inoculate engineering yeast into the fermentation tank.
There are several bio-chemical reactions happen in the fermentation tank. [2-3]. During this process, besides the lipid, some other by-products will be acquired as well, like CO2for example. CO2 can be transform to dry ice which may use as gas fertilizer.
There are several different types of fermentation tanks and we plan to use mechanical agitating fermentation tank. The use of mechanical agitation to stir materials to produce axial and radial flow, so that the mixture of materials in the tank is good, the solid in the liquid to maintain suspension state, conducive to solid and nutrients fully contact, easy to absorb nutrients; On the other hand, it can break bubbles, increase gas-liquid contact area, improve the mass transfer rate between gas and liquid, strengthen oxygen transfer effect and eliminate foam[4]
- Fig.2 Diagram of fermentation tank structure and paddle stirrers (left);Animation of fermentation tank working principle (right)
6. After fermentation we will obtain harvested oleaginous yeast biomass.
7. Extracting the lipid from harvested oleaginous yeast biomass. Using three-phase centrifugal separator to separate lipid and wastewater from residues respectively.[5]
- Fig.3 Schematic diagram of three-phase centrifugal separator
8. Adding catalyst and CH3OH into the lipid and finish the transesterification, acquiring biodiesel and glycerol. Catalyzed transesterification process can be achieved by homogeneous, heterogeneous or enzymatic catalysts, and the most substantial procedure is using homogenous acid/base catalysts[6-9]. For example KOH/NaOH are used to convert the oil into fatty acid methyl esters (FAME) [10] The chemical process of transesterification show as below: 11]
9. Separation of biodiesel and glycerol. For an optimum degree of transesterification, the resulting glycerol must be separated as quickly and completely as possible. Centrifugal separators have proven effective in these tasks over decades. The separated glycerol/water mixture can be processed for use as a raw material in the pharmaceuticals and cosmetics industries.[12]
10. Biodiesel will be supply to fuel station and used alone or in combination with petrol-diesel for diesel engine.[13-14](See Fig. 4) [15-16]
- Fig. 4 Biodiesel fuel station in Iwoa, U.S. (left) and Shanghai, China (right)
References
- [1] Sujit K. Mohanty, Manas R. Swain. Bioethanol Production from Food Crops -Sustainable Sources, Interventions, and Challenges, Chapter 3 - Bioethanol Production From Corn and Wheat: Food, Fuel, and Future, Academic Press, Pages 45-59, https://doi.org/10.1016/C2017-0-00234-3
- [2] Saville, B.A., Griffin, W.M., MacLean, H.L., 2016. Ethanol production technologies in the US: status and future de¬velopments. In: Salles-Filho, Sergio LuizMonteiro, Bar¬bosa Cortez, Luis Augusto, Jardim da Silveira, José Maria Ferreira, Trindade, S., da Graça Derengowski Fonseca, M. (Eds.), Global Bioethanol Evolution, Risks, and Uncer¬tainties. Academic Press, Cambridge, MA, pp. 163–180, Chapter 7.
- [3] Yeshitila Asteraye Tsigiea, Chun-Yuan Wanga, Chi-Thanh Truongb, Yi-Hsu Jua. Lipid production from Yarrowia lipolytica Po1g grown in sugarcane bagasse hydrolysate. Bioresource Technology, 102 (2011), 9216–9222
- [4] Yan Li, Principles and Techniques of Fermentation Engineering, Higher Education Press, Beijing China, 2007
- [5] Biodiesel, Fields of application of Flottweg, https://www.flottweg.com/applications/edible-fats-and-oils-biofuels/biodiesel/ Retrieved Oct.22 2020
- [6] Alok Patel, Neha Arora, Juhi Mehtani, Vikas Pruthi, Parul A. Pruthi, Assessment of fuel properties on the basis of fatty acid profiles of oleaginous yeast for potential biodiesel production, Renewable and Sustainable Energy Reviews 77 (2017) 604–616
- [7] Chen CL, Huang CC, Ho KC, Hsiao PX, Wu MS, Chang JS. Biodiesel production from wet microalgae feedstock using sequential wet extraction/transesterification and direct transesterification processes. Bioresour Technol 2015;194:179–86.
- [8] Demirbas A. Progress and recent trends in biodiesel fuels. Energy Convers Manag 2009;50:14–34.
- [9] Knothe G, Razon LF. Biodiesel fuels. Prog Energy Combust Sci 2017;58:36–59.
- [10] Baskar G, Aiswarya R. Trends in catalytic production of biodiesel from various feedstocks. Renew Sustain Energy Rev 2016;57:496–504.
- [11] AN Wen-jie, XU De-ping, WANG Hai-jing, Chemical Production Methods of the Biodiesel Fuel, Cereals & Oils, 2005;7:3-6.
- [12] Separator, Product line of Flottweg, https://www.flottweg.com/product-lines/separator/3-phase-separator/, Retrieved Oct.22 2020
- [13] NIE Xiao-an, JIANG Jian-chun, Conversion Technology and Utilization of Biomass Energy(V)--The Industrialized Preparation Technology of Biodiesel, Biomass Chemical Engineering, Vol. 42 No. 1 Jan. 2008:58-62
- [14] Omidvarborna Hamid, Kumar, Ashok; Kim, Dong-Shik. Characterization of particulate matter emitted from transit buses fueled with B20 in idle modes. Journal of Environmental Chemical Engineering. 2 (4): 2335–2342.
- [15] Eugene Mulero, Iowa Rep. Abby Finkenauer Introduces Biodiesel Tax Credit Legislation, Transport Topics, April 9 2019 1:00 PM EDT, https://www.ttnews.com/articles/iowa-rep-abby-finkenauer-introduces-biodiesel-tax-credit-legislation, Retrieved Oct.22 2020
- [16] CCTV exposure: “Gutter oil” "transformed" biodiesel on the market – Whether cars are ok to "drink" “gutter oil”? Sohu News, Nov.18 2017, https://www.sohu.com/a/203185154_658403, Retrieved Oct.22 2020