Waste Management
Safely disposing normal solid or semisolid materials, resulting from human and animal activities, that are useless, unwanted, or hazardious is a big problem today. Solid wastes typically may be classified as follows:
Garbage: decomposable wastes from food.
Rubbish: nondecomposable wastes, either combustible (such as paper, wood, and cloth) or noncombustible (such as metal, glass and ceramics).
Ashes: residues of the combustion of solid fuels.
Large wastes: demolition and construction debris and trees.
Dead Animals
Sewage-treatment solids: material retained on sawage-treatment screens, settled solids, and biomass sludge.
Industrial wastes: such materials as chemicals, paints and sand.
Mining wastes: slag heaps and coal refuse piles.
Agricultural wastes: farm animal manure and crop residues.
eWastes: computer, its parts and chemicals.
Hazardous Wastes: Hazardous wastes have been difined as wastes that pose a potential hazard to humans or living organisms for one or more of the folowing reasons:
(i) Such wastes are nondegradable or persistent in nature;
(ii) Their effects can be modified by organisms in the environment;
(iii) They may cause detrimental cumulative effects. General categories of hazardious wastes include toxic chemicals and flammable, radioactive, or solid.
(vi) They can cause detrimental cumulative effects.
Radioactive substances are hazardous because prolonged exposure to ionizing radiation often results in damage to living organisms, and the substances may persist over long periods of time. Management of radioactive and other hazardious wastes is subject to federal and state regulations, but no method has yet proven satisfactory for disposing of radioactive wastes.
Disposal Methods Disposal of solid wastes on land is by far the most common method and probably accounts for more than 90% of the nation's municipal refuse. Incineration accounts for the most of the remainder, whereas composting of solid wastes accounts for only an insignificant amount. Selecting a disposal method depends almost on costs, which in turn are likely to reflect local circumstances.
(a) Landfill: Sanitary landfill is the cheapest satisfactory means of disposal, but only of suitable land is within economic range of the source of the wastes; typically, collection and transportation account for 75% of the total cost of solid waste management. In a modern landfill, refuse if spread in thin layer, each of which is compacted by a bulldozer before the next is spread. When about 3mt of refuse is been laid down, it is coversd by a thin layer of clean earth, which also is compacted. Pollution of surface and groundwater os minimised by lining and contouring the fill, compacting and planing the cover, selecting proper soil, diverting upland drainage, and placing wastes in sites not subject to flooding or high groundwater levels.
Gases are generated in landfills throgh anaerobic secomposition of organic solid waste. If a significant amount of methane is present, it may be explosive; proper venting eliminates this problem.
(b) Incinerators: In incinerators of conventional design, refuse in burned on moving grates in refractory-lined chambers; combustible gases and solids they carry and burned in secondary chambers. Combustible is 85 to 90% complete for the combustible materials. Emmisions of fly ash and other particles are often controlled by wet scrubbers, electrostatic precilitators, and bag filters.
(c) Compositing: Compositing operations of solid wastes include preparing refuse and degradading organic matter by aerobic microorganisms. Refuse is presorted, to remove materials that might have salvage value or cannot be composted, and is ground up to improve the efficient of the decompostion process. The refuse is placed in long piles on the ground or deposited in mechanical systems, where it is degraded biologically to a humus with a total nitrogen, phosphorous, and potassium content of 1 to 3%, depending on the material being composted. After about three weeks, the product is ready for curing, blending with addictive, bagging, and marketing.
Resource Recovery Numeous thermall process, now in various stages of developmant, recover energy in one form or another form solid wastes. These systems fall into two groups: combustion process. A number of companies burn in-plant wastes in conventional incinerators to produce steam. A few municipalities produce steam in incinerators in which the walls of the combustion chamber are linked with boiler tubes; the water circulted through the tubes absorbs heat generated in the combustion chamber and produces stream.
Pyrolysis, also called destructive distillation, is the process f chemically decomposition solid wastes by heat in an oxygen-reduced atmosphere. This results in a gas stream containing priparily hydrogen, methane, carbon monoxide, carbon dioxide, and various other gases and inert ash, depending on the material being pyrolysed.
Recycling: The practice of reycling solid waste is an ancient one. Metal implements were melted down and recast in prehistoric times. Today, recyclable materials are recovered from municipal refuse by a number of methods, including shredding, magnetic seperation of metals, air classification that seperates light and heavy frictions, screening, and washing. Another method of recoveriny is mixed with with water and ground into refuse is mixed with in the wet pulping process: Incoming refuse is mixed with water and ground into a slurry in the wet pulper, with resembles a large kitchen disposal unit. Large pieces of metal and other nonpulpable materials are pulled out by a magnetic device before the slurry from the pulper is loaded into a centrifuge called a liquid cyclone. Here the heavier noncombustibles, such as glass, metals, and ceramics are seperated and sent on other, lighter metarials go to a paperfebre-recovery system.
The final residue is either incrinerarted or used as landfill. Municipalities private refuse-collection organisations require those who generate solid waste to keep bottles, cans, newspapers, cardboard, and other recyclable items seperate from other wastes.
Safely disposing normal solid or semisolid materials, resulting from human and animal activities, that are useless, unwanted, or hazardious is a big problem today. Solid wastes typically may be classified as follows:
Garbage: decomposable wastes from food.
Rubbish: nondecomposable wastes, either combustible (such as paper, wood, and cloth) or noncombustible (such as metal, glass and ceramics).
Ashes: residues of the combustion of solid fuels.
Large wastes: demolition and construction debris and trees.
Dead Animals
Sewage-treatment solids: material retained on sawage-treatment screens, settled solids, and biomass sludge.
Industrial wastes: such materials as chemicals, paints and sand.
Mining wastes: slag heaps and coal refuse piles.
Agricultural wastes: farm animal manure and crop residues.
eWastes: computer, its parts and chemicals.
Hazardous Wastes: Hazardous wastes have been difined as wastes that pose a potential hazard to humans or living organisms for one or more of the folowing reasons:
(i) Such wastes are nondegradable or persistent in nature;
(ii) Their effects can be modified by organisms in the environment;
(iii) They may cause detrimental cumulative effects. General categories of hazardious wastes include toxic chemicals and flammable, radioactive, or solid.
(vi) They can cause detrimental cumulative effects.
Radioactive substances are hazardous because prolonged exposure to ionizing radiation often results in damage to living organisms, and the substances may persist over long periods of time. Management of radioactive and other hazardious wastes is subject to federal and state regulations, but no method has yet proven satisfactory for disposing of radioactive wastes.
Disposal Methods Disposal of solid wastes on land is by far the most common method and probably accounts for more than 90% of the nation's municipal refuse. Incineration accounts for the most of the remainder, whereas composting of solid wastes accounts for only an insignificant amount. Selecting a disposal method depends almost on costs, which in turn are likely to reflect local circumstances.
(a) Landfill: Sanitary landfill is the cheapest satisfactory means of disposal, but only of suitable land is within economic range of the source of the wastes; typically, collection and transportation account for 75% of the total cost of solid waste management. In a modern landfill, refuse if spread in thin layer, each of which is compacted by a bulldozer before the next is spread. When about 3mt of refuse is been laid down, it is coversd by a thin layer of clean earth, which also is compacted. Pollution of surface and groundwater os minimised by lining and contouring the fill, compacting and planing the cover, selecting proper soil, diverting upland drainage, and placing wastes in sites not subject to flooding or high groundwater levels.
Gases are generated in landfills throgh anaerobic secomposition of organic solid waste. If a significant amount of methane is present, it may be explosive; proper venting eliminates this problem.
(b) Incinerators: In incinerators of conventional design, refuse in burned on moving grates in refractory-lined chambers; combustible gases and solids they carry and burned in secondary chambers. Combustible is 85 to 90% complete for the combustible materials. Emmisions of fly ash and other particles are often controlled by wet scrubbers, electrostatic precilitators, and bag filters.
(c) Compositing: Compositing operations of solid wastes include preparing refuse and degradading organic matter by aerobic microorganisms. Refuse is presorted, to remove materials that might have salvage value or cannot be composted, and is ground up to improve the efficient of the decompostion process. The refuse is placed in long piles on the ground or deposited in mechanical systems, where it is degraded biologically to a humus with a total nitrogen, phosphorous, and potassium content of 1 to 3%, depending on the material being composted. After about three weeks, the product is ready for curing, blending with addictive, bagging, and marketing.
Resource Recovery Numeous thermall process, now in various stages of developmant, recover energy in one form or another form solid wastes. These systems fall into two groups: combustion process. A number of companies burn in-plant wastes in conventional incinerators to produce steam. A few municipalities produce steam in incinerators in which the walls of the combustion chamber are linked with boiler tubes; the water circulted through the tubes absorbs heat generated in the combustion chamber and produces stream.
Pyrolysis, also called destructive distillation, is the process f chemically decomposition solid wastes by heat in an oxygen-reduced atmosphere. This results in a gas stream containing priparily hydrogen, methane, carbon monoxide, carbon dioxide, and various other gases and inert ash, depending on the material being pyrolysed.
Recycling: The practice of reycling solid waste is an ancient one. Metal implements were melted down and recast in prehistoric times. Today, recyclable materials are recovered from municipal refuse by a number of methods, including shredding, magnetic seperation of metals, air classification that seperates light and heavy frictions, screening, and washing. Another method of recoveriny is mixed with with water and ground into refuse is mixed with in the wet pulping process: Incoming refuse is mixed with water and ground into a slurry in the wet pulper, with resembles a large kitchen disposal unit. Large pieces of metal and other nonpulpable materials are pulled out by a magnetic device before the slurry from the pulper is loaded into a centrifuge called a liquid cyclone. Here the heavier noncombustibles, such as glass, metals, and ceramics are seperated and sent on other, lighter metarials go to a paperfebre-recovery system.
The final residue is either incrinerarted or used as landfill. Municipalities private refuse-collection organisations require those who generate solid waste to keep bottles, cans, newspapers, cardboard, and other recyclable items seperate from other wastes.
This is really true, i agree with you Moses. You did great job. All of us need to be more responsible for the wonderful world God has given us, and we are the one create the world that is desirable to live. Lets protect God's creation for the next generations.
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