- Animal farm residues such as dung, droppings, urine, etc., have to be gainfully utilized.
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It is required to also use slaughterhouse waste such as ruminal contents, blood, urine, meat and fat trimmings to derive maximum advantage.
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It is necessary to devise ways and means for thorough and innovative utilization of all the inedible parts of the animal.
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By utilizing the slaughterhouse waste the pollution problems and the light and heating source to the slaughterhouse itself can be alleviated.
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Buffalo and cattle dung is converted into dried cakes and used as a cooking fuel in almost all the Indian villages and sub urban areas.
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The dung compost, when applied to soil, retains its humus content and maintains its fertility.
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Of the total quantity of dung produced from buffaloes and cattle, almost 2/3 is used as fuel and 1/3 as manure.
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Dung and urine are rich source of organic matter and nitrogen. Cattle dung is also used to give a thin covering to the floor of the huts for ages.
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This cover serves as a temporary plaster and is repeatedly applied after a week or so.
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It is a practice in many parts of India that the sheep flock owners are paid for grazing their stock on the fields after harvest for the value of manure.
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By grazing sheep faeces and urine deposited on the land will contribute to the soil fertility and crop yield.
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The organic waste available through animal industry can be utilised in several different ways.
Production of biogas for light and heat
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It involves the anaerobic fermentation of faeces, urine and slaughterhouse waste to produce biogas (largely methane).
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This process also yields high quality manure as a byproduct.
A biogas producing plant comprises of three components
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Digester:
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Gasometer:
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Pipes:
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A digester is made up of bricks as a circular cylinder.
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In small plants, gasometer is an inverted iron movable cover of digester itself, which rises or descends according to the gas it contains.
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The entire assembly has to be water and gas proof.
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The receptacle or inlet feeds the digester with animal blood, urine, dung, ruminal contents, effluents, etc., at regular intervals.
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These organic and nitrogenous animal wastes undergo anaerobic fermentation.
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As a result, biogas consisting of nearly 60% methane, 30% carbon dioxide and traces of hydrogen, carbon monoxide, etc., are produced.
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Methane burns with a blue alongwith traces of orange flame and does not form any smoke.
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Impure methane as produced in this plant burns in a mixture of 93% air and 7% gas.
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During filling of digester with waste material, water is so added that it remains almost 0.5 m above the waste.
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Some old sludge is also added for rapid fermentation.
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Gas production will start after a week.
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A discharge hole is provided near the bottom of the digester for periodic removal of the digested or spent slurry, which is an excellent compost fertilizer.
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Biogas plants have a great potential in augmenting the development of rural industries.
Production of compost manure
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In places where no better utilization of organic matter of animal origin is feasible, it can be composted to yield manure of reasonably good quality.
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This manure contains nitrogen, phosphorus, potassium and trace minerals essential for plant growth and improved soil structure.
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Compost making units at some distance from the slaughterhouses will utilize the blood, ruminal and intestinal contents, bedding waste from lairages, meat and fat trimmings, floor washings, hair, feather, etc.
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Even condemned meat and offal, if reduced to chunks and spread out in the middle of the heap, can be used in compost making.
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Compost pit or bunkers can be made up of bricks leaving enough open spaces in the walls.
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Coarse materials such as maize or millet stalks or small twigs are laid at the bottom for proper ventilation.
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Then alternate layers of ruminal and intestinal contents or vegetable matter and slaughterhouse waste are laid upto 2 metres.
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The outer side and top of the heap is protected clean soil or grass.
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In tropical climate, the temperature inside the heap will go up to 75oC killing the larvae and checking the entry of undesirable pests.
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In dry weather, it has to be wet periodically to allow aerobic bacterial decomposition.
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That is why proper ventilation of the heap is also essential.
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Some people use rejected pieces of corrugated sheets to ensure it.
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To achieve uniform decomposition, the material has to be turned atleast three times after 20, 40 and 60 days.
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In about 90 days, the material is fully decomposed into compost manure.
Production of animal glue
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Hide trimmings and fleshing, pig skin, sinews, tendons scattered and weathered bones and their pieces can be used for the production of glue.
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Horns and hoofs, ears, lips, snouts, tails, etc., can also be utilized for the same purpose.
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It requires simple equipment and people with very little education can be trained to produce this good value material.
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Glue is extensively used in match, paper and rug industries, plywood making, carpet sizing and production of imitation leather.
Production of pig feed from paunch and intestinal contents
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The average weight of the paunch contents of cattle, sheep and lambs are 27, 2.7 and 1.7 kg, respectively.
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The liquid fraction of the material can be separated from the fibrous residue by using a press.
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The fibrous fraction can be used as a fuel whereas the protein in the paunch contents can be concentrated for utilization as pig feed.
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It has been suggested that this use will reduce the cost of disposal of paunch contents by about 50%.
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Slaughterhouse waste posed a big disposal problem for a long time but it has now been realized that with the advancement of technology, this waste can be recycled to several different uses to derive financial and sanitary benefits.
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In this context, simple equipment should be designed and available manpower within the country should be engaged.
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It will create new employment an dskill as well.
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