Optimization of Biogas Production From Slaughterhouse Waste and Digester Sizing: A Case in Addis Ababa Abattoirs Enterprise
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2016-07
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Addis Ababa University
Abstract
This study focuses on production of biogas from slaughter house waste to generate optimal methane yield. Which has high calorific value under Optimum temperature, pH and substrate proportion (blood, manure and undigested stomach content). And also Digester Design for dumping waste of AAAE. In this study first experiment was carried out to determine pH, total solid, volatile solid and ash content of each type of waste fermented independently at optimal temperature (350c) and at pH 7. Second experiment was by mixing three type of wastes based on crossed D-Optimal design expert software which had 42 run at different proportion of substrate Blood and Manure at range of (10%-20%)’ undigested stomach content at range of (60%-80%) , pH range (4-10) and temperature at range of (20oc-45oc).
After the experiment the following parameters: methane content, caloric value or energy generation capacity and volume of biogas, pH, temperature, total solid, volatile solids, and Ash content of each type of waste were determined. From individual type of 350ml sample waste (blood, manure and undigested stomach content) Maximum Biogas production and methane composition was 0, 7lit, 4lit and 0%, 66% and 54% respectively. From 42 run experimental result by crossed D-Optimal Design Expert software the best optimal methane composition and biogas production was 79.26% and 0.381lit/gm of VS respectively. Optimal condition was 20% blood, 20% manure and 60% undigested stomach content substrate composition, at pH=7.88 and temperature 32.49oc. 79.26%CH4 composition has a potential 7.88kwh per m3 of Biogas. The amount of biogas produce from AAAE waste is2968m3/day which has a potential to generate 23,393.4kwh/day of energy. 3,148.8 kwh/day apply to facilitate anaerobic digestion activity and remaining 17, 207.9kwh/day for steam generation. Which can cover for 70.7% of boiler furnace oil and gas oil consumption and save7, 087,740.ETB birr/year of its budget.
This study has shown that application of biogas plant for AAAE is financially, environmentally and socially feasible. The cost benefit analysis shows that NPV is positive and benefit cost ratio is 2.03 which is greater than the proposed value for application of given project. As the financial analysis shows after implementation of this project AAAE can annually save Birr 6,006,520. Which can be invested to construct four digester plants having a volume of 753.75m3 with daily 120.6m3 total feedstock fed to the digesters. At optimal mixture of three waste and optimal condition.
Key words- Digester, Biogas, Methane, slaughterhouse waste, anaerobic digestion
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Keywords
Digester, Biogas, Methane, Slaughterhouse, Waste anaerobic digestion