Photo 1: Inlet and outlet of four treatments
Photo 2: Cover by bamboo wood
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MEKARN MSc 2008-10 |
Miniprojects |
Nowadays, developing worlds are facing a low living standard and dangers to the environment because of increasing population, exploitation of natural resources and growth of industries, and at the same time increasing demand for food and fuel. Especially oil price has been increased day by day and nobody knows when it will reach to the peak and then find the constant price. These problems have led to scientific and social imitative focused on sustainable development including the use of renewable energy sources. In ASEAN member countries, energy from biomass such as wood and agricultural residues represents about 40% of the total energy consumption, equivalent to some 2.5 million Tetra-joules per year. The bulk is from wood, with an estimated value of US$ 7 billions per year (Biomass energy in ASEAN member countries 1997).
Biodigesters play an important role in the recycling of organic wastes, producing methane-rich gas for cooking, with positive impacts on the environment and on human and animal health (Preston and Rodríguez 1998). Soeurn Than (1994) and Bui Xuan An et al (1997a) showed that biodigesters made from tubular polyethylene were well accepted when introduced to households in rural areas of Laos, Cambodia and Vietnam because of the low price and simple installation. The impact of the technology in South Vietnam is demonstrated by the more than 30,000 units that have been paid for and installed by farmers between 1996 and 2002 (Duong Nguyen Khang et al 2000). Biodigesters provide methane-rich gas for cooking while the effluent is a good source of fertilizer nutrients for crops growing on land and water (Kean Sophea and Preston 2001), for fishponds (Pich Sophin and Preston 2001; San Thy and Preston 2003).
There is therefore an urgent need to develop alternative energy sources. For rural areas, the use of local resources in integrated farming systems is projected to bring most benefit to small scale farmers and the environment (Leng and Preston 2005). The recycling of livestock wastes through biodigesters with low cost to produce biogas for cooking and nutrient-rich effluent as fertilizer is one of the ways to reduce dependence on fossil fuel-derived inputs in an environmentally friendly way that benefits small scale farmers (Preston 2000).
ˇ The hypothesis is that mixing every day will increase the production of gas.
ˇ The aim of this experiment is to compare the gas production rate in different days of mixing.
The experiment will be conducted in the experimental farm of Kampong Cham National School of Agriculture, Kampong Cham Province which is located approximately 124 km North East of Phnom Penh City, Cambodia. The experiment will last for 30 days starting from 8 August 2008 to 6 September 2008.
Four plug-flow tubular biodigesters made of tubular polyethylene film will be used for the experiments. Each treatment will be put 3 kg of fresh pig manure mixing with 17 litres of water daily in the morning between 7:00-8:00 Am. Four treatments will be:
ˇ M0: No mixing
ˇ M3: Mixing every 3rd day
ˇ M2: Mixing every 2nd day
ˇ M1: Mixing every day
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Photo 1: Inlet and outlet of four treatments |
Photo 2: Cover by bamboo wood |
ˇ 4 mini-biodigesters (2m long*0.5 m diameter) with brick walls.
ˇ 4 Plastic containers (40 litres capacity) for gas measurement by water displacement
ˇ 4 Plastic containers (10 litres capacity) for collection of effluent
ˇ PVC tubes: 5 m of ID 10cm; 20 m of ID 12mm; 5m plastic hose-pipe of 15mm ID.
ˇ Tubular plastic (20 m of diameter 0.5m)
ˇ 5 m of bamboo
ˇ 4 Plastic buckets (10 litre capacity)
ˇ 100 kg pig (or cattle) manure at beginning then 15 kg daily for 30 days.
Scale of 60 kg
Ruler
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Table 1: Details of the biodigesters |
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Dimensions |
M0 |
M3 |
M2 |
M1 |
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Biodigester details |
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Length, m |
2 |
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Diameter, m |
0.60 |
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Volume of biodigester, m3 |
0.64 |
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Liquid volume, litres |
560 |
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Initial applied water, litres |
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400 |
400 |
400 |
400 |
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Initial fresh pig manure, kg |
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30 |
30 |
30 |
30 |
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Liquid applied daily, litres |
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15 |
15 |
15 |
15 |
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Manure, kg/d |
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5 |
5 |
5 |
5 |
Pig manure
Pig manure will be collected daily in the early morning from the same pig farm during the experimental period of 30 days. Pig manure will be put into the biodigester in the morning before mixing.
Biodigesters
Four flow biodigesters are made from tubular polyethylene film with internal diameter of 0.60 m and are mounted in shallow trenches lined with bricks walls to ensure the dimensions were exactly the same (2 m length, 0.60 m depth and 0.60 m width), to provide a liquid volume in the proportion of 75% of the total biodigester capacity. The biodigesters will be installed in an area with the same climatic condition covering with bamboo fence to protect from sharp material. At the beginning, each biodigester will be put 400 litres of water and 30 kg of pig manure. After that each biodigester will be put 17 litres of water and 3 kg of fresh pig manure daily.
Data collection
Data will be recorded every day by measuring the level of gas production before adding pig manure and before mixing it and the amount of effluent.
Fresh pig manure will be analyzed every day for dry matter (DM) and weekly for nitrogen (N) and ammonia nitrogen according to the AOAC (1990).
The data will be analysed by regression. Mixing rate is the independent variable.
AOAC 1990 Official methods of analysis. Association of Official Analytical Chemists,
Arlington, Virginia, 15th edition, 1298 pp. .
Biomass energy in Aseavariabn member countries 1997 "Biomass: more than a traditional form of energy". FAO Regional Wood Energy Development Programme in Asia in cooperation with the ASEAN-EC Energy Management Training Center and the EC-ASEAN-COGEN progamme.
Bui Xuan An, Preston T R and Dolberg F 1997 The introduction of low-cost polyethylene tube biodigesters on small scale farms in Vietnam, Livestock Research for Rural Development, 9:2 http://www.cipav.org.co/lrrd/lrrd9/2/an92.htm
Duong Nguyen Khang and Le Minh Tuan*2002 Transferring the low cost plastic film biodigester technology to farmers Proceedings Biodigester Workshop March 2002. http://www.mekarn.org/procbiod/khang2a.htm
Kean Sophea and Preston T R 2001 Comparison of biodigester effluent and urea as fertilizer for water spinachvegetable. Livestock Research for Rural Development 13 (6) http://www.cipav.org.co/lrrd/lrrd13/6/pich136.htm
Leng R A and Preston T R 2005 Implications for livestock production of the decline in world oil reserves; Workshop-seminar "Making better use of local feed resources" (Editors: Reg Preston and Brian Ogle) MEKARN-CTU, Cantho, 23-25 May, 2005. Article #2. Retrieved , from http://www.mekarn.org/proctu/leng.htm.htm
Preston and Rodríguez 1998 Gas production from pig manure fed at different loading rates to polyethylene tubular biodigesters
Preston T R 2000 Livestock Production from Local Resources in an Integrated Farming System; a Sustainable Alternative for the Benefit of Small Scale Farmers and the Environment. Workshop-seminar "Making better use of local feed resources" January, 2000. SAREC-UAF (Editors: T R Preston and R B Ogle). http://www.forum.org.kh/~wwwuta/sarpro/preston.htm
Pich Sophin and Preston T R 2001 Effect of processing pig manure in a biodigester as fertilizer input for ponds growing fish in polyculture. Livestock Research for Rural Development. (13) 6. http://www.cipav.org.co/lrrd/lrrd13/6/pich136.htm
San Thy and Preston T R 2003 Effluent from biodigesters with different retention times for primary production and feed of Tilapia (Oreochromis niloticus). MSc Thesis, MEKARN-SLU
Soeurn Than 1994. Low cost biodigesters in Cambodia. Proc. National Seminar-workshop in sustainable Livestock Prod. on local feed resources. Agricultural Publishing House, Ho Chi Minh, pp.109-112.