Waste Desposal

WASTE MANAGEMENT Waste management is the collection ,transport, processing ,recycling or disposal of waste materials.
The term usually relates to materials produced by humanactivity, and is generally undertaken to reduce their effect onhealth, theenvironmentor aesthetics. Waste management is also carried out to recover resourcesfrom it. Waste management can involvesolid,liquid,gaseousor radioactivesubstances, with different methods and fields of expertise for each.Waste management practices differ for developed and developing nations, for urban and rural areas, and for residential and industrial, producers. Management for non-hazardous residential and institutional waste in metropolitan areas isusually the responsibility of local government authorities, while management for non-hazardous commercial and industrial waste is usually the responsibility of the generator .Solid Waste Disposal, disposal of normally solid or semisolid materials, resulting from human and animal activities, that are useless, unwanted, or hazardous. Solid wastes typically may be classified as follows:
Garbage:
Decomposable wastes from food Rubbish:
Non decomposable wastes, either combustible (such as paper, wood, andcloth) or noncombustible (such as metal, glass, and ceramics) Ashes: residues of the combustion of solid fuels Large wastes: demolition and construction debris and trees
Sewage-treatment solids: material retained on sewage-treatment screens, settledsolids, 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.
WASTE MANAGEMENT METHODS
Waste management methods vary widely between areas for many reasons,including type of waste material, nearby land uses, and the area available

DISPOSAL METHODS1. LANDFILL
Disposing of waste in a landfill involves burying waste to dispose it off, and this remains a common practice in most countries. Landfills were often established in abandoned or unused quarries mining voids or borrow pits. A properly-designed and well-managed landfill can be a hygienic and relatively inexpensive method of disposing of waste materials. Older, poorly-designed or poorly-managed landfillscan create a number of adverse environmental impacts such as wind-blownlitter ,attraction of vermin, and generation of liquidleachate. Another common byproductof landfills is gas (mostly composed of methaneandcarbon dioxide), which is produced as organic waste breaks downanaerobically. This gas can create odor problems, kill surface vegetation, and is agreenhouse gas. Sanitary landfill is the cheapest satisfactory means of disposal, but only if suitableland is within economic range of the source of the wastes; typically, collection andtransportation account for 75 percent of the total cost of solid waste management.In a modern landfill, refuse is spread in thin layers, each of which is compacted bya bulldozer before the next is spread. When about 3 m (about 10 ft) of refuse has been laid down, it is covered by a thin layer of clean earth, which also iscompacted. Pollution of surface and groundwater is minimized by lining andcontouring the fill, compacting and planting 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 through anaerobicdecomposition of organic solid waste. If a significant amount of methane is present, it may be explosive; proper venting eliminates this problem

2.
INCINERATION
Incineration is a disposal method that involvescombustionof waste material.Incineration and other high temperature waste treatment systems are sometimesdescribed as "thermal treatment". Incinerators convert waste materials intoheat,gas,steam, andash.Incineration is carried out both on a small scale by individuals and on a large scale by industry. It is used to dispose of solid, liquid and gaseous waste. It is recognizedas a practical method of disposing of certainhazardous wastematerials (such as biologicalmedical waste). Incineration is a controversial method of waste disposal,due to issues such as emission of gaseous pollutants.Incineration is common in countries such asJapanwhere land is more scarce, asthese facilities generally do not require as much area as landfills.waste-to-energy (WtE) or energy-from-waste (EfW) are broad terms for facilities that burn waste ina furnace or boiler to generate heat, steam and/or electricity. Combustion in anincinerator is not always perfect and there have been concerns about micro- pollutants in gaseous emissions from incinerator stacks. Particular concern hasfocused on some very persistent organics such asdioxinswhich may be createdwithin the incinerator and which may have serious environmental consequences inthe area immediately around the incinerator. On the other hand this method produces heat that can be used as energy.

RECYCLING METHODS
The process of extracting resources or value from waste is generally referred to asrecycling, meaning to recover or reuse the material. There are a number of differentmethods by which waste material is recycled: the raw materials may be extractedand reprocessed, or the calorific content of the waste may be converted toelectricity. New methods of recycling are being developed continuously, and aredescribed briefly below.

PHYSICAL REPROCESSING
The popular meaning of ‘recycling’ in most developed countries refers to thewidespread collection and reuse of everyday waste materials such as empty beverage containers. These are collected and sorted into common types so that theraw materials from which the items are made can be reprocessed into new products. Material for recycling may be collected separately from general wasteusing dedicated bins and collection vehicles, or sorted directly from mixed waste

The most common consumer products recycled includealuminumbeverage cans,steelfood and aerosol cans,HDPEandPETbottles,glassbottles and jars, paperboard cartons,newspapers, magazines, andcardboard. Other types of plastic(PVC,LDPE,PP, andPS: seeresin identification code) are also recyclable,although these are not as commonly collected. These items are usually composedof a single type of material, making them relatively easy to recycle into new products. The recycling of complex products (such as computers and electronicequipment) is more difficult, due to the additional dismantling and separationrequired.

BIOLOGICAL REPROCESSING
Waste materials that are organic in nature, such as plant material, food scraps, and paper products, can be recycled using biological composting and digestion processes todecomposethe organic matter. The resulting organic material is thenrecycled asmulchor compostfor agricultural or landscaping purposes. In addition,waste gas from the process (such as methane) can be captured and used for generating electricity. The intention of biological processing in waste managementis to control and accelerate the natural process of decomposition of organic matter.There are a large variety of composting and digestion methods and technologiesvarying in complexity from simple home compost heaps, to industrial-scaleenclosed-vessel digestion of mixed domestic waste (seeMechanical biological treatment). Methods of biological decomposition are differentiated as beingaerobic or anaerobicmethods, though hybrids of the two methods also exist
An example of waste management through composting is theGreen Bin Program inToronto, Canada, where household organic waste (such as kitchen scraps and plant cuttings) are collected in a dedicated container and then composted.

ENERGY RECOVERY
The energy content of waste products can be harnessed directly by using them as adirect combustion fuel, or indirectly by processing them into another type of fuel.Recycling through thermal treatment ranges from using waste as a fuel source for cooking or heating, to fuel for boilersto generate steam and electricity in aturbine.Pyrolysisandgasificationare two related forms of thermal treatment where wastematerials are heated to high temperatures with limitedoxygenavailability. The process typically occurs in a sealed vessel under high pressure. Pyrolysis of solidwaste converts the material into solid, liquid and gas products. The liquid and gascan be burnt to produce energy or refined into other products. The solid residue(char) can be further refined into products such asactivated carbon. Gasificationand advancedPlasma arc gasificationare used to convert organic materials directlyinto a synthetic gas (syngas) composed of carbon monoxideandhydrogen. The gasis then burnt to produce electricity andsteam.

4 COMPOSTING
Composting operations of solid wastes include preparing refuse and degradingorganic matter by aerobic microorganisms. Refuse is presorted, to removematerials that might have salvage value or cannot be composted, and is ground upto improve the efficiency of the decomposition process. The refuse is placed inlong piles on the ground or deposited in mechanical systems, where it is degraded biologically to a humus with a total nitrogen, phosphorus, and potassium content of 1 to 3 percent, depending on the material being composted. After about threeweeks, the product is ready for curing, blending with additives, bagging, andmarketing.

WASTE MANAGEMENT * Waste management is the collection ,transport, processing, recycling or disposal of waste materials.
The term usually relates to materials produced by human activity, and is generally undertaken to reduce their effect on health, the environment or aesthetics.

Waste management can involve solid, liquid, gaseous or Radioactive substances, with different methods and fields of expertise for each.
Waste management is also carried out to recover resources from it

Solid Waste Disposal, disposal of normally solid or semisolid materials, resulting from human and animal activities, that are useless, unwanted, or hazardous. Solid wastes typically may be classified as follows:

Garbage:
Decomposable wastes from food Rubbish:
Non decomposable 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
Sewage-treatment solids:
Material retained on sewage-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.

DISPOSAL METHODS
1. LANDFILL
Disposing of waste in a landfill involves burying waste to dispose it off, and this remains a common practice in most countries.

2.
INCINERATION
Incineration is a disposal method that involves combustion of waste material. incineration and other high temperature waste treatment systems are sometimes described as "thermal treatment". Incinerators convert waste materials into heat, gas, steam, and ash. Incineration is carried out both on a small scale by individuals and on a large scale by industry.

RECYCLING METHODS
The process of extracting resources or value from waste is generally referred to as recycling, meaning to recover or reuse the material.

PHYSICAL REPROCESSING
The popular meaning of ‘recycling’ in most developed countries refers to the widespread collection and reuse of everyday waste materials such as empty beverage containers. These are collected and sorted into common types so that the raw materials from which the items are made can be reprocessed into new products

BIOLOGICAL REPROCESSING
Waste materials that are organic in nature, such as plant material, food scraps, and paper products, can be recycled using biological composting and digestion processes to decompose the organic matter

4 COMPOSTING
Composting operations of solid wastes include preparing refuse and Degrading organic matter by aerobic microorganisms.