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Senior design proposal presentation 10 15
- 1. Ben Leppard, Charles Griffin, Kaylynn Smalls Anaerobic Digestion of Food Waste From Clemson University Dining Facilities
- 2. Presentation Overview ◼ Problem Statement ◼ Anaerobic Digestion Overview ◼ Goals ◼ Feedstock Data ◼ Energy, Thermal, Mass Balance ◼ Reactor Sizing ◼ Biogas Production ◼ Possible Designs ◼ Sustainability ◼ Budget ◼ References
- 3. PROBLEM ◼ According to the EPA, in the United States, approximately 21% of waste that goes into landfills and incinerators comes from food waste; this is about 35 million tons of waste (Resource Conservation). ◼ Clemson University produces about 675 tons of food waste per year ◼ Only about 270 tons per year are composted. http://www.epa.gov/foodrecovery /
- 4. ANAEROBIC DIGESTION OVERVIEW ◼ Process where microorganism break down organic compounds in anoxic environments and produce biogas. ◼ Consist of 4 major parts ▪ Hydrolysis ▪ Acidogenesis ▪ Acetogenesis ▪ Methanogenesis http://www.magheebioenergy.in/wp - content/uploads/2013/12/BiogasPr edictionandDesignofFoodWastetoE nergySystemELSEVIER20111.pdf
- 5. GOALS ◼ Design an Anaerobic Digester that create biogas from Clemson food waste. ◼ Convert 50 % of the food waste from Harcombe & Schilletter to biogas
- 6. CONSTRAINTS ◼ High Variability of Feedstock ◼ Time-3 months to research, and test design. Anaerobic digesters need to operate for at least 20 days. ◼ Budgetary-$1,050 allowance
- 7. QUESTIONS TO BE ADDRESSED User ▪ How much food waste can the anaerobic digester handle? ▪ How much would it cost to operate the anaerobic digester? ▪ How much space will the anaerobic digester take up? Client ▪ How much would it cost to fabricate the anaerobic digester? ▪ How much methane will be produced by the anaerobic digester? ▪ How long will it take before methane can be produced? Designer ▪ Where is the anaerobic digester going to be placed? ▪ What is the composition of the food waste? ▪ Will other substrates need to be added to improve the anaerobic digester?
- 9. QUALITY OF FEEDSTOCK ◼ Light Metals ◼ Heavy Metals ◼ pH ◼ C:N Ratio ◼ TS/VS Concentration
- 10. ANALYSIS OF DATA From the data, the team determined the food waste had a low Carbon to Nitrogen Ratio. It was 12:21, it needed to be in the range of 20:1-40:1, therefore the team decided to use a cosubstrate. Glycerol was chosen because it has a high volatile solid content and carbon concentration.
- 11. AGRICULTURE LAB VOLATILE SOLID CALCULATION %VS (Dry) = 100 - %ASH (Dry) = 100 - 3.2% = 96.8%VS
- 12. TEAM’S CALCULATION OF VOLATILE SOLID
- 13. THERMAL & FLOW RATE BALANCES
- 14. C1=Food Waste C2=Glycerol C3=Mixed Stream M1=Mass Flow Rate Carbon Nitrogen C2: MASS BALANCE
- 15. CARBON NITROGEN RATIO The team decide on a ratio of 30.1 because it was in the middle of the acceptable range for carbon to nitrogen. Since we decided to use this ratio the flow rates became
- 16. VOLATILE SOLID MASS BALANCE C1=Food Waste C2=Glycerol C3=Mixed Stream
- 17. REACTOR SIZING
- 18. ORGANIC LOADING RATE Determining the Organic Loading Rate is very important for designing an anaerobic digestion. If the organic loading rate is too high, there is a risk of substrate inhibition; it causes an accumulation of volatile free fatty acids which inhibits the rest of the reactions; this is not good for the process.
- 23. VARIOUS DESIGNS ◼ Batch vs. Continuous ◼ Vertical vs. Horizontal ◼ Single vs. Multi-Stage ◼ Thermophilic vs. Mesophilic
- 24. POSSIBLE DESIGNS
- 25. COMPUTER MODEL Biogas Production Time [Days] Biogas [kg]
- 26. SUSTAINABILITY MEASURES ◼ More ecologically friendly than landfilling or incineration ◼ Provides a valuable product from waste that is often disposed of ◼ Is a sustainable fuel source ◼ Reduces transportation costs to landfill (monetary, carbon, labor, equipment) ◼ Economically viable (net metering, disposal savings, carbon credits) ◼ Environmentally responsible (less need for landfill volume, reduced GHG emissions,) ◼ Socially Equitable (localized waste disposal) ◼ Sustainable Materials: waste glycerol(adding carbon), waste food, used equipment, water neutral process, carbon neutral process
- 27. TIME LINE
- 28. BUDGET
- 29. LITERATURE C. Zhang, S. Haijia, J. Baeyens, and T. Tianwei. 2014 . Reviewing the anaerobic digestion of food waste for biogas production. Renewable and Sustainable Energy Reviews. 38: 383-392. ●Role and optimal levels of important parameters, an approximate amount of food waste by country, average food waste composition. C. Drapcho, N. Nhuan, T. Walker. 2008. Chapter 9: Methane. In Biofuels Engineering Process Technology, 329-337. New York, N. Y.: McGraw Hill. ●It detailed the 4 steps that compose anaerobic digestion. It discussed possible enzymes that could be used to help hydrolysis and fermentation. It stated that theoretically carbs yield lower methane. .While proteins and lipids yield higher methane. A COD:N:P ratio of 300:5:1 was given as an adequate ratio for digestion. EPA, L. Moody. Using Biochemical Methane Potentials and Anaerobic Toxicity Assays. Available at http://www.epa.gov/agstar/documents/conf10/Moody_Final.pdf. Accessed on September 9, 2014. ●This is more information from Moody, an agricultural scientist at Iowa State, explaining the benefits of testing feedstock prior to designing a digester.
- 30. REFERENCES C. Zhang, S. Haijia, J. Baeyens, and T. Tianwei. 2014 . Reviewing the anaerobic digestion of food waste for biogas production. Renewable and Sustainable Energy Reviews. 38: 383-392. C. Banks. Anaerobic digestion and energy. University of Southampton. Available at: http://www.valorgas.soton.ac.uk/Pub_docs/JyU%20SS%202011/CB%204.pdf. Accessed 8 September 2014. C.J. Banks, Y. Zhang, Y. Jiang, S. Heaven. 2012. Trace element requirements for stable food waste digestion at elevated ammonia concentrations. Bioresource Technology. 104: 127-135. C. Chu, Y. Lu, K. Xu, Y. Ebie, Y. Inamori, H. Kong. 2008. A pH- and temperature-phased two-stage process for hydrogen and methane production from food waste. Intl. J. Hydrogen Energy. 33(18): 4739-4746.
Editor's Notes
- Charles
- Charles
- Charles
- Kaylynn Hydrolysis: Process where polymers are broken down to monomers Fermentation occurs which create short chain organic acids like propionate and succinate. It also creates carbon dioxide, ammonia, and hydrogen Acetogeneiss: Acetogenic bacteria convert organic acids into acetic acid, along with more hydrogen, carbon dioxide, ammonia. Methanogenesis-Methane is formed,methanogenec bacteria converts products from acetogenesis into methane & CO2
- Charles
- Charles, be sure to explain what we mean by variability ; transportation constraint - distance from dining halls to digester location
- Ben
- Ben ; re-enter data e.g. C:N ratio
- Kaylynn From the data from the lab, there is a very small amount of light and heavy metals in the food stock. Which is great because light and heavy metals can inactivate a wide range of enzyme function and structures which would not be good for the reaction. From the data the pH was 4 in order to get it to an acceptable range for anaerobic digestion which is about 7 sodium bicarbonate and potassium bicarbonate could be added.
- Kaylynn
- Ben
- Ben
- Kaylynn
- Kaylynn We did a carbon and nitrogen balance with hopes of determining the correct flow rates of glycerol and food waste so that we could get the correct ratio of carbon to nitrogen in the reactor. To find C3 the food waste (c1*m1) & glycerol(c2*m2) terms were added then divided by m3, which came from m1+m2
- Kaylynn Iteration was done to determine the correct ratio of Carbon to Nitrogen and to determine the flow rates. To determine the ratio, C3 of carbon was divided by the C3 value of nitrogen. The team decide on a ratio of 30.1 because it was in the middle of the acceptable range.
- Ben
- Kaylynn The next step in design was determining the reactor size where anaerobic digestion would take place. In order to get the correct values volumetric flow rates of food waste and glycerol we had to divide by their individual densities since they are different values. We couldn't simply take the mass flow rates. So assuming a retention time of 20 days we came up with a reactor size of 84 m3
- Kaylynn Determining the Organic Loading Rate is very important for designing an anaerobic digestion. If the organic loading rate is too high, there is a risk of substrate inhibition; it causes an accumulation of Volatile free fatty acids which inhibit the reaction, which is not good for the process. Depending on what literature you read the organic loading rate ranges from 1-10kg/m3 per day.
- Kaylynn From the equation on the previous page you can see that Organic Loading rate is affected by both volume and retention time. We picked various retention times and saw how that affected the reactor volume and OLR.
- Kaylynn The team decided to use a shorter retention time which allowed us to have a smaller reactor which would cut down cost. With these parameters the OLR was 7.6 which is in the acceptable range.
- Ben
- Charles ; commas for every three values ; density → fraction
- Ben Horizontal: volume between 50-150, Vertical: volume between 300-1500m3, normally composed of cheaper material. Single stage 1 step. Multistage splits up reactions but could be used to optimizer reactions.Thermophilic process has faster kinetic & higher methane production. Mesophilic is susceptible to temperature fluctuations, and normally longer RT are needed.
- Ben Continuous because we have 2 flow streams, glycerol & food waste. Vertical because less expensive and can be made from cheaper materials, and it is less complicated to construct. Single stage because it’s widely used in industry. We decided on thermohilic because that’s what most reactors in industry are ran under. We have a storage for the digestate, the gas would be collected in the reactor., with a flexible foil membrane over top.
- Ben
- Charles Are any sustainable materials going to be used, are we adding carbon or reducing it, are we going to use water
- Anyone
- Charles, make sure you can explain where the values came from ; remove .00 ; Electricity spelling ; commas
- Anyone
- Anyone