BIOGAS AND BIO-FERTILIZER PRODUCTION FROM COW DUNG FOR SUSTAINABLE ECONOMIC DEVELOPMENT
Santanu Nath1, Susmita Majumder2,
- Division of Livestock Products Technology, ICAR-IVRI Bareilly (U.P.)
- Division of Physiology & Climatology, ICAR-IVRI Bareilly (U.P.)
ABSTRACT
Though cattle are mostly reared for milk and beef production, various other by-products may be obtained from cattle, if they are harvested and processed in scientific and efficient manner. In fact, rearing of cattle only for milk and meat production, thereby neglecting the by-products utilization certainly decreases the revenue of the farmers. Among the potentially the valuable by-products, dung are often given less importance, as far as industrial and commercial exploitation is concerned. In Ayurveda, cow dung is considered as ‘universal purifier’ of all waste materials. Cow dung has been traditionally used as fuel, fly and mosquito repellent etc. In addition to this, commercial exploitation of cow dung by converting it into biogas and bio- fertilizer will result into economic development of farmers. It will further aid in combating environmental concerns like Global Warming and minimize the use of chemical fertilizers which are considered to have deleterious effect on “soil health” in long run. This will support overall sustainable development.
INTRODUCTION
Fossil fuels are non-renewable resource. Burning of fossil fuel results in the release of gases responsible for Green House Effect. High dependency on it lead to crude oil price increment and it is surged more rapidly. Continuous consumption of fossil fuels will likely to lead to the exhaustation of oil reserves of the world. So, renewable energy source like biogas has bright prospects in the future to come. Like many other organic waste materials, cow dung may be used for the production of biogas to generate electricity and heat. Biogas mainly consists of methane and little carbon dioxide and is scatterly used in rural regions of India, Bangladesh, Pakistan and elsewhere to provide a renewable source of electricity and energy. In India, it is commonly known as “Gobar gas”. The term “Gobar” refers to “Dung”. The principle of extracting biogas is relatively easy and the system for biogas extraction can be installed at small scale also. The cake obtained from it may be again further processed to obtain bio-fertilizer.
COW DUNG
Cow dung can be defined as the undigested residue of consumed food material being excreted by herbivorous bovine animal species. Being a mixture of faeces and urine in the ratio of 3:1, it mainly consists of lignin, cellulose, hemicelluloses. It also contain 24 different minerals like nitrogen, potassium, along with trace amount of sulpher, iron, magnesium, copper, cobalt, manganese (Kartikey et al, 2016).
69.9% of Indian population resides in rural India (Hindu, 2011) and cow is the major cattle and generates 15 kg dung/ day (Werner et. al., 1989). Cow dung in India is also used as co-product in agriculture as manure, biofertilizer, pesticide, pest-repellent and as a source of energy. According to Ayurveda, it can also act as purifier for all the wastes in the nature (Randhwa and Khullar, 2011).
Bio gas:-
Bio gas may be defined as the mixer of gasses produced by breakdown of organic matter in the absence of oxygen. It primarily consists of methane and carbon dioxide. Some methanogenic bacteria are responsible for the production of biogas by means of some biochemical process. As it is originates from bio chemical process, it is called as biogas.
Biogas can be compressed the same way as natural gas is compressed to CNG. In India, it has been estimated that the total potential of biogas production from different organic waste is about 40.734 Mm₃/ year. It is estimated that India can produce power of about 17000 MW using biogas which is about 10 % of countries energy requirements (Rupnar et al., 2018).
COW DUNG; A RAW MATERIAL FOR BIOGAS PRODUCTION
According to the 20th livestock census, India is the home of 535.78 million livestock with 192.49 million cattles and 109.85 million buffaloes. Cattles and buffaloes are noteworthy source of dung, an important raw material of biogas. The average dung yield from cattles is about 4.5 kg/day and that of buffaloes is 10.2 kg/day (fresh weight) (Rupnar et al., 2018).
Abundance of raw materials, which sometime are not used efficiently in India, provides a bright prospect in the future. One kilogram of cow manure can produce 35-40 litres of biogas when mixed with equal amount of water with hydraulic retention time(HRT) of 55-60 days maintained at ambient temperature of 24-26 ͦ C (Kalia and singh, 2004).
Dung generated from 3-5 cattle/ day can run a simple 8-10 m₃ biogas plant which is sufficient for a family of 6-8 persons, can cook meals for 2-3 times or may light two lamps for 3 hour or run a refrigerator for all day and can also operate a 3 Kilowatt power for 1 hour (Warner et. al, 1989).
On the other hand, farmers also gain 13.87 metric tons of organic fertilizer per year from the biogas plant. This co-production of fertilizer also allow farmer to recover initial investment for seeting up of a biogas plant (Sharma, 2011). It has been also found that addition of pig dung have an enhanced effect. Mixture of cow dung and pig dung (60:40) showed 10% increase in methane production (Li et. al., 2014). Use of potato pulp and cow manure in the ratio of 20:80 also produced fair amount of methane in comparison to pure cow dung (Sanaei-Moghadam et al., 2014).
BIOGAS PRODUCTION PROCESS
Biogas production is done in anaerobic in nature and takes place in two stages. They are acid formation stage and methane formation stage. In the acid formation stage, bio-degradable complex organic compound present in the waste materials are acted upon by a group of acid forming bacteria present in the dung. Organic acid are the main product of this stage. In the second stage, a group of methanogenic bacteria acts upon the organic acids to produce methane gas (Vikaspedia.in).
Component of biogas plant:
- Mixing tanks: The feed materials (dung) are collected in mixing tank, sufficient water is added and the material is mixed thoroughly till homogenous slurry is formed.
- Inlet pipe: Substrate is discharged into the digester through the inlet pipe / tank.
- Digester: Slurry is fermented inside the digester and biogas is produced through bacterial action.
- Gas holder or gas storage dome: Biogas is collected in the gas holder, which holds the gas until the time of consumption.
- Outlet pipe: Digested slurry is discharged into the outlet tank either through outlet pipe or the opening provided in the digester.
- Gas pipeline: The gas pipe line carries the gas to the point of utilization, such as stove or lamp (Vipaskedia.in).
CONCLUSION
India being a developing country, about 70% of the population resides in rural area and they are mainly dependant on the farming and agriculture. India is the home of largest number of cattle and buffaloes. Due to this huge amount of dung are produce continuously which are not always efficiently utilized. If they are utilized efficiently as a biogas it may replace the used of LPG and CNG, thus providing a major contribution in sustainable development. On the other hand, bio-fertilizer obtained during the processing of dung in the digester may also serve as a means of subsidiary income to the farmers.
References:
Current status of cow dung as a bioresource for sustainable development: Kartikey Kumar Gupta, Kamal Rai Aneja and Deepanshu Rana
The Hindu (2011) “About 70 per cent Indians live in rural areas: Census report.” http://www.thehindu.com/news/national/about70percentindiansliveinruralareascensusreport/article2230211.ece. Accessed 24 Jul 2015
Werner U, Stöhr U, Hees N (1989) Biogas plants in animal husbandry. Deutsches Zentrum für Entwicklungstechnologien-GATE
Randhawa GK, Kullar JS (2011) Bioremediation of pharmaceuticals, pesticides, and petrochemicals with gomeya/cow dung. ISRN Pharmacol. doi:10.5402/2011/362459
Rupnar, A.K., Sudhir Jain and Panwar, N.L. 2018. Biogas in India: Potential and Integration into Present Energy Systems. Int.J.Curr.Microbiol.App.Sci. 7(07): 2175-2186. doi: https://doi.org/10.20546/ijcmas.2018.707.257
Kalia A, Singh S (2004) Development of a biogas plant. Energy Sources 26:707–714
Sharma CK (2011). Biogas—a boon for India. Biofuels 2–3
Li J, Jha AK, Bajracharya TR (2014) Dry anaerobic co-digestion of cow dung with pig manure for methane production. Appl Biochem Biotechnol 173:1537–1552
Sanaei-Moghadam A, Abbaspour-Fard MH, Aghel H, Aghkhani MH, AbediniTorghabeh J (2014) Enhancement of biogas production by co-digestion of potato pulp with cow manure in a CSTR system. Appl Biochem Biotechnol 173:1858–1869
