Waste Disposal 2

Waste Disposal

WHAT IS WASTE?

• Waste is an unwanted or undesired material or substance. It was commonly referred as rubbish , trash, garbage or junk depending upon the type of material and the regional terminology.

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Waste is directly linked to the human development, both technologically and socially. With industrial development and innovation being directly linked to waste materials, examples are plastics and nuclear technology.

Types of Wastes

• Waste can be divided into different types. There are many different kinds of waste, including solid, liquid, gaseous, hazardous, radioactive, and medical.

SOLID WASTES

• Solid wastes are waste materials that contain less than 70% water

“Solid” wastes include: • forest and wood processing residues;

• agricultural crop residues;

• municipal solid wastes (MSW), which is domestic refuse, commercial wastes and industrial wastes, such as pallets, paper, cardboard and plastics.

Methods of disposing Solid Wastes

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LANDFILL - a waste disposal site in which each day’s accumulation of debris is covered by a blanket of sediment. - trucks bring in days waste, place it in active area where it is compacted and at the end of the day covered by layer of sediment - Each day’s accumulation unit is called a cell. Fill is capped with impervious clay to prevent infiltration and percolation of water through the fill. Fill bottom is lined and provided with a drainage system to contain and remove any leakage or leachate that occurs. Monitoring wells provide a final check.

Problems of Landfills • Leachate generation and groundwater contamination • Methane production • Incomplete decomposition • Settling

INCINERATION • A disposal method that involves combustion of waste material. It is sometimes described as "thermal treatment" and usually convert waste materials into heat, gas, steam, and ash.

Incineration Hazards • There are arising economic problems because trash is not an ideal fuel. • The incineration of certain waste products produces acidic gases that corrode the furnace walls. Polyvinyl chloride (PVC) is notorious, a plastic used in the manufacture of rainwear, toys, containers, garden hoses, and records. Hydrogen chloride gas were produce when PVC are burned. This gas reacts with water to produce hydrochloric acid, a strongly corrosive liquid. • What’s threatening is the fact that some of the PVC decomposes before it burns completely. Decomposition products such as vinyl chloride, or suspected ones such as, dioxin are known carcinogens. Most of these can be removed from the exhaust stream if proper air pollution controls are installed, but these measures are never 100 percent effective and so expensive.

RECYCLING • Reclaiming ( waste materials, as newsprint, bottles, etc.) by using in the manufacture of new products. • Environmentally favorable way of reducing waste for it conserves material resources.

You buy something in a plastic bottle. The new plastic items are sold in shops. The plastic flakes are melted down and can be made into new items. The sorted plastic is washed and shredded into small flakes.

you wash and squash your empty bottle and take it to a plastic bottle recycling bank, or you may be able to put it in your recycling box/bin at home. The plastic bottles are taken to a factory for recycling. The bottles are sorted into different types of plastic to be recycled separately.

Various Recycling Routes for Some Common Wastes Waste Paper Glass Tire

Food scraps

Recycling Possibilities Repulp to reclaim fiber Compost Crush and remelt for glass manufacture Shred and use for manufacture of new tires Grind and use as additive in road construction Sterilize and use as a hog food Compost

LIQUID WASTES

“Liquid” wastes include: • • • •

sewage sludge and effluent; animal wastes; food processing residues; and industrial effluents.

Methods of disposing Liquid Wastes

Deep-Well Injection THEORY

Practice

A well is drilled in a dry porous layer and wastes are pumped in. Contamination of groundwater is prevented by the casing and seal around the portion of the well that penetrates groundwater.

1. Wastes spill or leak at surface. 2. Corrosion of casing allows waste to escape. 3. Inadequate seal permits waste to back-flow 4. Fractures existing or caused by earthquakes or the introduction of fluids, allow wastes to escape into groundwater.

Surface Impoundments THEORY

PRACTICE

Wastes in large volumes of water are put into impoundments (ponds), where water evaporates and wastes accumulate.

1.Leaks in transport pipe 2.Exceptional rainfall causes overflow. 3.Bottom of impoundmet may be inadequately sealed or lack plastic liner and/or sufficient clay. 4.Plastic liner is ruptured by freezing or deteriorates. 5.Many hazardous wastes are volatile. Hence this method allows them to evaporate and become dispersed in the environment

Landfills Theory

PRACTICE

Wastes are carefully contained to prevent cross-mixing of reactive substances. Fill is capped with impervious clay to prevent infiltration and percolation of water through the fill. Fill bottom is lined and provided with a drainage system to contain and remove any leakage or leachate that occurs. Monitoring wells provide a final check.

1.Burrowing animals make holes in clay cap. 2.Freezing temperatures shrink and tear liner. 3.Error in storage allows reactive chemicals to mix, triggering an explosion. 4.Chemicals corrode collection pipes, preventing effective withdrawal. 5.Plume of leaking wastes bypasses monitoring well.

RADIOACTIVE WASTE

• Radioactive waste (or nuclear waste) is a material deemed no longer useful that has been contaminated by or contains radionuclides. • Radioactive wastes are waste types containing radioactive chemical elements that do not have a practical purpose. • Radioactive waste can contain radionuclides of very light elements, such as radioactive hydrogen (tritium), or of very heavy elements, such as uranium. • Radioactive waste is classified as high, intermediate, or low level. Depending on the radionuclides contained in it,

Disposal of Radioactive Wastes •

*Short term containment (a few years) to allow the radioactive decay of short lived isotopes. Wastes can be handled much more easily and safely after this occurs. *Ultimate long-term containment ( tens of thousands of years) to provide protection from the long lived isotopes.

MEDICAL WASTES

• Medical waste, are known as clinical waste, normally refers to waste products that cannot be considered general waste, produced from healthcare premises, such as hospitals. • Medical waste is generated by medical research and by the medical treatment of human beings and animals.

Medical waste “includes” • • • •

soiled bandages culture dishes surgical gloves instruments (including needles) • and as well as human tissue.

Treatment of Medical Wastes

INCINERATION • Incineration is the burning of waste in temperatures ranging from 1,800ºF to 2,000ºF (982ºC to 1093ºC).

Advantages of using incineration • The process of incineration provides the advantage of volume reduction as well as the ability to dispose of recognizable waste and sharps. • On site incinerators provide a quick and easy way of disposing medical waste. The ash that results from combustion can be sent to a sanitary landfill.

Disadvantages of using incineration • The disadvantage lies in the incinerator emissions. These emissions may contain gases that are toxic.

• We have to be our own leaders in the battle versus waste disposal, because we are the only ones who care about our future on this earth………