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  • Mar 5th, 2005
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Landhi Cattle Colony, Bin Qasim Town, Karachi, Pakistan is a gargantuan cattle colony, a blessing of the Almighty God that harbours a black-gold-mine which can emanate million of dollars. It is one of the largest cattle colony in the world where more than 250,000 high breed buffaloes (Nili-Ravi, Kundi``) and cows (Red Sindhi, Sahiwal, Bhagnari, Dhanni) are being nurtured, nourished and reared. An average animal excretes more than 15 Kgs of dung daily that amounts to the tune of approximately 37.5 tonnes per day, are being embezzled and frittered away into the Arabian sea consistently.

Cattle are such animals even a hair of them is pricey. All products of the cow, including dung (or "gobar" in Urdu) are considered purifying agents by Hindus.

In the classical Indian epic, the Mahabharata, "gobar is described as the living place of Lakshmi, the goddess of wealth." Traditionally both in Pakistan and India, dung is collected in villages and fashioned into dung-cakes, to be burned directly as fuel or composted for fertiliser.

Dung accounts for over 21 percent of total rural energy use in India, and as much as 40 percent in certain states.

Usually, dung used for one purpose is lost to the other, but biogas which consists of 60 to 80% methane, 20 to 40% carbon dioxide and several trace compounds such as hydrogen sulfide and ammonia. provides a means to both ends.

It exploits the caloric content of the waste, while retaining the nutrients as fertiliser - and on both counts, it is more efficient than traditional methods. Direct burning only captures about 11 percent of the dung's energy value, but biogas generation has a 45 to 60 percent efficiency.

In other words, biogas captures approximately 5 times as much energy as does direct burning. And the by-product 'slurry' has twice the nitrogen content of composted dung because open-air composting allows much of the nitrogen to escape in the form of volatile compounds.

The slurry also releases its nutrients more readily than composted dung. And unlike decomposing dung, it is odourless and does not attract flies or mosquitoes. It actually repels termites, and restrains weed growth.

Biogas, as its name suggests, is produced by extracting chemical energy from organic materials. This process takes place in a sealed container known as a 'biogas digester'. The digester is usually a squat, cement cylinder two to four meters in diameter, with a duct in the side that allows the dung or other organic wastes to be fed in, along with water.

In ambient temperatures of 25 to 35 degrees centigrade, the material soon begins to ferment. This produces a mixture of gases, primarily methane and carbon dioxide, and a nutrient-rich slurry. The gas is drawn out through a valve at the top of the digester, and the slurry is drained off into settling troughs at its base.

Methane is the combustible component of biogas. It is piped into homes to be used as a cooking fuel, or used to fire a diesel engine to generate electricity. The slurry is such an excellent fertiliser that it's often more highly valued than the gas - biogas plants are often called "biofertilizer plants."

In addition to the slurry's nutrient recycling function, the gas itself has important environmental benefits.

It offers an ecologically sustainable alternative to fuel wood.

Biogas can help check deforestation. And since the conversion process in the digester is anaerobic (it occurs in the absence of oxygen), it destroys most of the pathogens present in dung and waste, thereby reducing the potential for infections like dysentery and enteritis.

The burning of traditional fuels like dung cakes or wood releases high levels of carbon monoxide, suspended particulates, hydrocarbons, and often, contaminants like sulfur oxides. (Dung contains traces of hydrogen sulfide, which is converted to sulfur oxides on combustion.) Exposure to these fumes in unvented cooking spaces increases the risk of respiratory disease.

According to a study sponsored by the World Health Organisation, women cooking over firewood inhale as much of the carcinogen benzopyrene - a combustion by-product of wood - as they would by smoking 20 packs of cigarettes a day. Because it is a gas, biogas burns much more efficiently than these solid fuels. It leaves very few contaminants, although it is true that biogas releases small quantities of sulfur oxides.

Biogas offers perhaps the most environmentally benign method for tapping the solar energy stored in bio-mass. It's a renewable and decentralised alternative to the other methane-based fuel, natural gas, which is commonly used in cities.

The gas is useful as a fuel substitute for firewood, dung, agricultural residues, petrol, diesel, and electricity, depending on the nature of the task, and local supply conditions and constraints, thus supplying energy for cooking and lighting. Biogas systems also provide a residue organic waste, after anaerobic digestion, that has superior nutrient qualities over the usual organic fertiliser, cattle dung, as it is in the form of ammonia.

Anaerobic digesters also function as a waste disposal system, particularly for human waste, and can, therefore, prevent potential sources of environmental contamination and the spread of pathogens. Small-scale industries are also made possible, from the sale of surplus gas to the provision of power for a rural-based industry, therefore, biogas may also provide the user with income generating opportunities.

The gas can also be used to power engines, in a dual fuel mix with petrol and diesel, and can aid in pumped irrigation systems.

The "biogas" plant has dramatically changed the lives of hundreds of families in Maira Khurd and other villages, some 65 kilometers south-west of the capital city Islamabad.

Women and young girls in the village, who earlier spent the better part of the day hunting for scarce fuel wood, now have time to go to school or tend newly planted kitchen gardens, which help feed the family.

"That a simple intervention of installing biogas plants in the rural households would make such a tremendous difference in people's life, was something nobody had conceived of.

More than 50 biogas machines have been installed in Maira Khurd, which are shared by the 400 families in the village. These biogas plants have helped many women in the village to take up work like embroidery and dyeing, which fetches some hard cash.

A typical rural family of six people uses 40 kilograms of wood per day to meet their fuel needs. Since a biogas unit needs only animal dung and water as raw materials, one can well imagine how many trees one biogas digester in a household could save.

This is not the last but the least. The biogas plants have also improved the health of women in Maira Khurd, as they no longer have to sit before smoke-belching kitchen stoves. Respiratory tract diseases, eye infections and coughs are on the decline in homes where biogas is in use. The biogas machines have helped improve environmental sanitation because the livestock excreta is no longer littered on the ground.

The health hazards of animal dung lying in the open have also been minimised as it is immediately fed into the biodigester.

China possesses biogas utilisation experience, with over 6 million household and around 700 industrial biogas digesters operating all across the country. Livestock husbandry in China is growing rapidly and contributing 30% to the total national agricultural output now. The fast-growing livestock farms have been discharging billions of tonnes of solid and liquid wastes.

In 1999, the Global Environment Fund (GEF) of United Nations Development Planning (UNDP), in co-operation with the State Economy and Trade Commission as well as the State Environment Protection Bureau of China, initiated a programme to accelerate the capacity establishment of China's commercialisation of RES and to explore great market potential in China. The industrialised biogas and water treatment demonstration project was one part of this programme, aiming at finding out the market feasibility of the corresponding technologies when applied into the organic waste water treatment process in China.

One demonstration project has been implemented in the Hangzhou Dengta Livestock Farm, which is a large-scale livestock farm with 120 000 pigs. Before the project was carried out, COD and BOD of the discharged waste from the farm were 17000mg/L and 8500mg/L respectively, far higher than the value regulated by the National Waste Water Discharge Standard of China.

After the project was put into operation, the pollutant discharge indexes have met the Standard. With this project, 4.94 million kWh electricity is generated from biogas annually. And with calculation of its financial status, this project has good commercialisation feasibility.

The success of this demonstration project has provided a good example for medium and large livestock farms in China to follow. With experience achieved hereby, solutions will be worked out in line with different resource and economic conditions of different regions, to better utilise local biogas resources and improve environmental situation.

In India more than 2 million biogas plants have been built so far. Almost 200,000 permanent jobs have been created for the male bread-winners of Indian families. With a potential market for 30 plants attached to households with 3 cattle or more, the social and environmental advantages of biogas are only just beginning to be explored.

Beef cattle feedlots in the Texas Panhandle produce more than 6 million beef cattle annually, and the manure from these feedlots represents a tremendous biogas energy potential. This project utilised laboratory and field experiments to evaluate biogas production from beef cattle manure scraped from open lots. The field project evaluated using landfill-type cells for producing biogas from beef cattle manure.

It is lucid, there is no denying and nobody can repudiate the fact that inspite of having superfluity and plethora of potential, the dairy sector has fallen victim to dereliction and perdition which is really vituperative.

My desideration is to titillate curiosities of those benefactors/entrepreneurs who are ebullient, harbour propensity and predilection, hallucinate to fall in with and bolster my view. We have to call forth all our energies in achieving success. I do not fancy to bludgeon anybody and to believe credulously but soliciting to be pragmatic.

My discernment and acumen do conjecture that the upshot of the investment as well as the prospect of being able to market the product look deucedly lucrative. This will bring not only good fortune for the indigent, impecunious dairy farmers but also alleviate unemployment problems of a burgeoning population in a strenuous manner.

Those who have volition and penchant, can imbibe the tenet to embark upon the project of "biogas excavation" in an inclusive way are supplicated to commune with "Dairy Farmers' Association, 90/4, Landhi Cattle Colony, Bin-Qasim town, Karachi, Phone: 5083018, Email: [email protected]" in a jiffy, without demur.

(The writer is a microbiologist, Dairy Farmers' Association Landhi Cattle Colony).

Copyright Business Recorder, 2005


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