The simulated result in Figure 11 shows the heat distribution over the mitad under no baking condition. Generally, the utilization of the biogas system and integration of the biogas injera baking stove will improve the overall food processing mechanism in the university. Table 12 tabulates the emission test results from the source tester and the data are similar to those of the official source tests in the past 7 years (Table 10). Characteristics and flow rates of feed streams to the anaerobic digesters. The distributions of heat over the mitad (baking stove) for 120 seconds are demonstrated shown in Figure 10. Dioxins/furans in the IC engine exhausts from tests conducted by the source tester. Therefore, the volume of the daily charge () is 1.48 m3/d. A recent study by California Energy Commission (CEC) estimated that, using existing infrastructure, co-digesting fats, oil, and grease (FOG), food processing waste, and dairy waste at the existing WWTPs could increase the biogas yield potential to 450 MW of capacity, representing 2,500 gigawatt hours (GWh) per year (Kulkarni, 2009). Increases in biopower production from sustainable biomass can provide many economic and environmental benefits, including creation of green jobs, promotion of local economic stability, and reduction of water and air pollution including greenhouse gas (GHG) emissions (O’Neill and Nuffer, 2011; California Energy Commission [CEC], 2012). Many wastewater treatment plants (WWTPs) use anaerobic digestion to reduce the volume of biosolids before disposal and/or reuse. The floating cover of each digester was replaced with a two-layer plastic membrane roof top with air in between to regulate the pressure inside the digesters. The primary sludge (PS) and the thickened waste activated sludge (TWAS), which is thickened by rotary drum thickeners (new), are fed to two mesophilic anaerobic digesters. Atse Fasil Campus cafeteria kitchen while baking injera from firewood. Investigation of Biogas Energy Yield from Local Food Waste and Integration of Biogas Digester and Baking Stove for Injera Preparation: A Case Study in the University of Gondar Student Cafeteria, Department of Mechanical Engineering, Institute of Technology/University of Gondar, Gondar, Ethiopia, Consider 15% of kitchen waste is nonbiodegradable, Consider 95% of food waste is biodegradable, Total mass of food waste per day from two, Total mass of kitchen waste per day from two, Then, the overall total mass of biodegradable,,, Food waste consists of fruit and food scrap obtained from a student after mealtime, Kitchen waste consists of vegetable waste or peel obtained from the preparation of food, K. D. Adem, D. A. Ambie, M. P. Arnavat, U. The average SO2 concentration from biogas-fueled combustion was also higher than that using NG (7 vs. 4 ppmv). 4, July 2015. When digester biogas is not available, the IC engine switches to natural gas (CMSA, 2013). Biogas is a combination of gases which are produced as a result of decomposition of organic matter such as food waste in the absence of oxygen. The slurry is then screened, by using a drum screen paddle mixer, to remove materials that are not readily digestible before being fed into the digesters (typically in late afternoons). The corresponding biogas generation rate is 10.2 ft3 biogas/lb (0.64 m3 biogas/kg) TS applied or 6.4 ft3 CH4/lb (0.40 m3 CH4/kg) TS applied, which is within the range of 6 to 8.5 ft3 CH4/lb (0.37 to 0.53 m3 CH4/kg) TS applied for food waste in literature, while the corresponding value for the municipal wastewater sludge is 5 ft3 CH4/lb (0.31 m3 CH4/kg) TS applied (EBMUD, 2008). A portable biogas analyzer, Gas Data GFM416 (Gas Data Limited, Whitley, Coventry, UK) was acquired for this project. Gas treatments for H2S removal include adsorption, chemical scrubbing, and biological scrubbing using biotrickling filters (Huertas et al., 2011). From the complete combustion process, the stoichiometric primary aeration required is 5.5; then, the entrainment ratio should be [10]. It is this air moving vertically away that draws in the cooler secondary air to the base of the flame. As shown, the average emissions from natural gas (NG)-fueled and biogas-fueled operations are: NOx at 15% O2 (38 ± 19 vs. 37 ± 20 ppm); CH4 (692 ± 83 vs. 1,065 ± 224 ppm); nonmethane organic carbon (NMOC) as C1 (45 ± 33 vs. 18 ± 6 ppm); total organic carbon (TOC) as C1 (735 ± 65 vs. 1,075 ± 227 ppm); CO2 (7.5 ± 0.5 vs. 12.8 ± 1.6%); CO at 15% O2 (122 ± 9 vs. 142 ± 14 ppm); O2 (7.9 ± 0.4 vs. 6.9 ± 0.7%); and SO2 (4 ± 3 vs. 7 ± 5 ppm). The designed system generates no smoke, and its efficiency is improved due to the addition of the insulation system and different layout used. Food waste is the second largest component of MSW, and it represents 15.5% of total MSW generated. The average total flow rate to the digesters was 57,300 gallons/day (217 m3/day), which contained 4.5% TS, and the VS percentage was 85.1%. The conversion of this food waste using the anaerobic digestion system yields 43.2m3biogas per day. The biogas or methane yield is measured by the amount of biogas or methane that can be produced per unit of volatile solids contained in the feedstock after subjecting it to anaerobic digestion for a sufficient amount of time under a given temperature. They are then mixed, ground, and recirculated in a storage tank for a couple of hours. With co-digestion of FOG, food waste, PS, and TWAS, the daily biogas yield has increased from 131,800 to 212,800 ft3 (3,730 to 6,030 m3)/day, a 61% increase. The heat flow through the wall is  kW, found from the following: The intensity leaving the burner is, found from the following: The shape factor is the heat flow through the stove per unit area of mitad; using Equation (16), it is found to be 1.79 kW/m2. With the average methane concentration of 62.6%, the heating value of the raw biogas is slightly greater than 600 BTU/ft3 (22,340 kJ/m3). According to the design in this study, the gas will be transported from the center of the dome as shown in Figure 13. Table 7. Therefore, the length of the flame that passes through each hole is 82 mm, found as in Equation (10) as shown in Figure 8. Evaluate the feasability of your biogas project for free with our biogas calculations tool. The concentrations of CH4, CO2, CO, NOx, and O2 are also similar to those measured by the portable emission analyzer (Table 11). Consequently, biogas also contains ammonia at a concentration in equilibrium with that in the digestate. The on-site treatment system is capable of reducing the H2S concentration below 15 ppmv. The information is needed for determining conditioning requirements of raw biogas for beneficial uses, for selecting power-generating equipment, and for air quality permitting. Utilizing the daily biogas generated for baking injera improves the overall food making process and reduces firewood consumption by 5.4%. The NOx emission limits can be as low as 9 parts per million by volume (ppmv) in some air pollution control districts (Drake, 2011; U.S. Department of Agriculture [USDA]/EPA/Department of Energy [DOE], 2015; Warner, 2009). From using CARB Method 428, octachlorodibenzodioxane (OCDD) was the only single PCDD/F species detected. The heat radiates at a rate of 1.79 kW/m2 to the bottom surface of 60 cm mitad. Table 9 tabulates the concentrations of those compounds detected in the raw biogas, effluent of the H2S adsorbers, and effluent of the siloxanes adsorbers. The loading rates of PS, TWAS, FOG, and food waste were recorded and used to calculate the mass loading rates to the digesters. Quality and quantity of biogas will be affected by many parameters, including pH, temperature, feed composition, loading rate, mixing condition, reactor design, and residence time. In the study, the measured average daily biodegradable food waste and kitchen waste generation rate in the campus is around 863 kg/day; this kitchen and food wastes are disposed at the backyard of the cafeteria. Utilizing the daily biogas generated for baking injera improves the overall food making process and reduces ・〉ewood consumption by 5.4%. The Central Marin Commercial Food-to-Energy Program is a public–private partnership between CMSA and Marin Sanitary Service (MSS). The size and shape of the injector orifice control the gas flow rate and hence heat input for a given gas composition and supply pressure. The analytical methods used were CARB 428 (PCDD/F), CARB 429 (PAHs), TO-14 (VOCs), and EPA 323 (formaldehyde). A modification in burner port design could also improve the overall performance of the baking system by allowing a free discharge of fuel which still remains to be investigated in the future. The dough is liquid enough to pour into the flat surface of the baking stove (mitad); the flat pancakes (injera) will have a smooth texture in the bottom side, the side that has direct contact with the stove (mitad); and the upper surface creates a porous-like profile called eye. This burner port size allows the biogas to flow into the baking mitad evenly. The conversion of this food waste using the anaerobic digestion system yields 43.2 m3 biogas per day. The average SO2 concentration from biogas-fueled combustion was also higher (7 vs. 4 ppmv), probably due to the presence of reduced sulfur compounds in the biogas.

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