Development of a household anaerobic digester for rural areas in Sudan

Öz

This study is aimed at developing an anaerobic digestion system that can produce biogas for cooking purposes at the household level. A lab-scale batch digester was designed and constructed using polypropylene material with a capacity of 20 litres, and with the biogas captured in a floating-top gas reservoir. This initial small-scale construction was mainly to study some important parameters of the anaerobic fermentation process. The parameters studied were: biogas production from various types of organic material, the levels of acidity and dry matter of the organic material, the affect of temperature within the container, along with an evaluation of the time scale and rate of gas production. Four types of organic material were used, including fresh and dry cow dung with dry matter content of 20% and 90% respectively, dry chicken manure with dry matter content of 90%, and food waste with dry matter content of 10%. The test conducted with fresh cow dung was at a time of low ambient temperature in the Sudanese winter, while the tests for the other three feedstock materials were conducted in the higher ambient temperature of the Sudanese summer. The results from the lab scale revealed that the gas production rate was directly proportional to the reactor temperature, while the dry matter contents in the organic material dictated the required mixing ratio with water. Using results from the lab-scale reactor, the digester design was improved and scaled up using a cylindrical water tank with a capacity of 225 litres. Using feedstock of 84.3 kg of fresh cow dung with dry matter of 20% dilutd with water to 10% dry matter, the design was tested at a digestate temperature of 37-38 degrees Celsius. The test covered the calorific value of gas produced, gas consumption rate using a single burner, and the efficiency of the burner. The results were that the calorific value of the biogas was 20.52 MJ/m³, the burner had a gas consumption of 342 liters per hour during a simulation of normal operation for household cooking use, and use of a standardized process indicated a burner efficiency of 51.7%.

Anahtar Kelimeler

• anaerobic digestion,biogas,household,rural areas,Sudan

Kaynakça

1. [1] Rajendran, K., Aslandzadeh, S. and Taherzadeh, M. J. (2012). Household biogas digesters – A Review, Energies; 5(8), 2911-2942; doi:10.3390/en5082911
2. [2] Jun Hou, Weifeng Zhang, Pei Wang, Zhengxia Dou, Liwei Gao and David Styles (2017). Greenhouse Gas Mitigation of Rural Household Biogas Systems in China: A Life Cycle Assessment. Energies; 10, 239; doi:10.3390/en10020239
3. [3] Sander Bruun a,n , Lars Stoumann Jensen a , Van Thi Khanh Vu b , Sven Sommer (2014). Small-scale household biogas digesters: An option for global warming mitigation or a potential climate bomb? Renewable and Sustainable. Energy Reviews; 33: 736–741
4. [4] Shaoqing Chen, Bin Chen, Dan Song (2012). Life-cycle energy production and emissions mitigation by comprehensive biogas–digestate utilization. Bioresource Technology; 114: 357–364.
5. [5] Shikun Cheng, Zifu Li, Heinz-Peter Mang, Elisabeth-Maria Huba, Ruiling Gao, Xuemei Wang (2014). Development and application of prefabricated biogas digesters in developing countries. Renewable and Sustainable, Energy Reviews; 34 :387–400.
6. [6] Thien Thu CT, Cuong PH, Hang LT, Chao NV, Anh LX, Trach NX, Sven G. Somme (2012). Management practices on biogas and non-biogas pig farms in developing countries – using livestock farms in Vietnam as an example. Journal of Cleaner Product; 27:64–71.
7. [7] Thanh Ba Ho , Timothy Kilgour Roberts and Steven Lucas (2015). Small-Scale Household Biogas Digesters as a Viable Option for Energy Recovery and Global Warming Mitigation—Vietnam Case Study. Journal of Agricultural Science and Technology A 5:387-395 doi: 10.17265/2161-6256/2015.06.002.