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Thursday, January 6, 2011

Handling and Management of Hazardous Waste

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Hazardous wastes cause pollutions in various ways. Pollutions of our resources through these wastes cause wide spread and often long term effects. A large number of diseases occur due to hazardous wastes. Thus these wastes make miserable the life of a common man and alter the normal environmental conditions. This is why proper handling and management of these wastes is most essential.

Reducing the strength of pollutants so as to make them neutral or less harmful together with their transport and safe disposal is called as handling and management of Hazardous Wastes. Certain principles, guidelines and control devices are necessary to be followed and adopted for handling and management of hazardous wastes. These principles and guidelines together with control measures are being given below.

There are various concepts of Handling and Management of Hazardous Wastes. The usage of those concepts varies from country to country and from region to region. The experts in the field of the management of hazardous wastes have gone ahead to four ‘RS’ against the earlier THREE ‘Rs’ Hierarchy. Now the expanded forms of these four ‘Rs’ as considered by environmentalists are: - 

Reduce- Reuse- Recycle – Re-think. The Hierarchy of four ‘Rs’ points towards some fundamental flaws and hence a thorough and effective system of handling and management of hazardous wastes must be applied in the current situations. The popularly applied practices of handling and management of hazardous waste during current age are briefly mentioned below-

A.     Reduction at Source: The word source means the place of origin – of the hazardous Waste. The ‘reduction at source’ means, decreasing or reducing the mass of waste by reducing its production, at the source of its origin. In fact, the best way of elimination of hazardous waste is not to generate it in the first place. In other words-

Reducing the volume of waste at the site of its production is called as Source Reduction. The reduction of Hazardous Waste at source may be done either by minimizing its production at first place or by replacing it by less toxic to non- toxic materials. Examples: Improved integrated circuits, replacement of toxic chlorinated hydrocarbons (1970s) by less toxic glycol ethers (1980s) and replacement of glycol ethers by low toxicity ethers (1990s).

B.     Recycling: The process of recovery or reuse of usable materials out of discarded wastes is called as recycling. For example about 15 per cent of Sulphuric acid is recycled in chemical manufacturing. During early days, all the sulphur needed for the production of sulphuric acid was taken out of mines directly. But, now with the prevailing tendencies of recycling, sulphuric acid manufacturing industries are using sulphur from smelters, refineries etc.Recycling is the process of recovery of used matter for further use through different methods like shredding, Magnetic Separation of metals, air classification, Screening, washing etc. Bottles, cans, news papers, card boards, and other items are recycled today to minimise waste. This process lessens the load at incinerators and landfills.

C.     Treatment: Various physical, chemical, and biological processes are employed for neutralising the hazardous effects of chemicals. These processes are called as treatment. Let us discuss these processes of handling and management of hazardous wastes one by one.

(i). Physical Treatment: The physical treatment of a hazardous waste means to alter  physical states of wastes so as to minimise, or neutralise their hazardous effects. This type of treatment incorporates activities both on micro and mega levels. At micro level the processes involved basically relate to separation of different types of wastes like liquid wastes and solid wastes. Some of these processes may be floatation, filtration, evaporation, stripping, screening, sedimentation and even, centrifugation. At mega level some of the popularly known processes are prolonged storage of the hazardous waste (so as to neutralise its toxicity or hazardousness); lagooning, and sludge drying. The prolonged storage of some nuclear or radiological wastes is done in view of making them harmless on the basis of the knowledge of their half life. The process of lagooning is the process and activity of constructing a shallow and protected body of wastes created by or near an industrial or waste site. 
Another method of handling and disposal of hazardous waste is solidification. It involves melting solid hazardous waste and mixing it with a binder. The binder is a substance that eventually hardens the mixture of wastes into an impenetrable mass. An important method treatment of radioactive wastes is turning it into a glass through a process known as vitrification.

 (ii).Chemical Treatment: Treatment of a hazardous waste by some specific chemical to neutralise its hazardous effects before releasing it into the environment, is called as chemical treatment For example, the application of sodium hydroxide to treat acid wastes at integrated circuit plants is a case which follows this rule. Now a day hydrochloric acid wastes are treated with lime which produces harmless calcium chloride. The sulphuric acid wastes can be treated with ammonia wastes forming ammonium sulphate which is a fertilizer.

(iii). Biological Treatment: The treatment of hazardous wastes involving biological agents for the neutralisation, decomposition, disintegration, and digestion of hazardous wastes is called as biological treatment of hazardous wastes. Composting, vermi-composting, manuring and sanitary land filling are some of the biological processes of hazardous waste treatment.

Key  words : Handling and Management, Hazardous Waste, biological treatment.

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