⚫Management of hazardous wastes
Hazardous wastes may remain dangerous for thousands of years.Tye hazardous waste include radioactive refuse, metallic compounds, organic solvents, acid asbestos, organic cyanide’s, hospital wastes, disposable medical equipments and tools.
The hazardous methods are adopted for the disposal of hazardous wastes.
⭐Landfills:There are permanent storage facilities for military related liquid and radioactive waste materials in secured lands.High level radio active wastes are stored in deep underground storage.
⭐Deep well injection:It involves drilling a well into dry,porous material below ground water.Hazardous waste liquids are pumped into the well.They are soaked into the porous material and made to remain isolated indefinitely.However fractures in the impermeable layer may permit the injected wastes to escape and contaminate ground water.
⭐ Surface impoundments:This method is used to dispose large amounts of water carrying relatively small amounts of chemical wastes.Surface impoundments are simple excavated depressions(ponds)into which liquid wastes are drained.Solid wastes settle and accumulate which water evaporates.If the pond bottom is well sealed and if evaporation equals input,wastes may be stored in the impoundment indefinitely.
⭐Incineration:The hazardous biomedical wastes are usually disposed off by means of Incineration.Human anatomical wastes,discarded medicines,toxic drugs,blood,pus, animal wastes,microbiological and biotechnological wastes etc are called Bio medical wastes.
⭐ Bioremediation:This is another rapidly developing clean up technology.Cleaning environment with biological options such as microbes and plants is called Bioremediation.Some naturally occurring bacteria and other microorganisms have the capability to degrade or absorb or detoxify the wastes such as heavy metals.
⚫ Management of non hazardous wastes
⭐ Sanitary land fills:The refuse is spread in a hollow land or in a trench and compacted with a layer of clear sand fill.The sanitary land fills are far more desirable than open dumps but the ground water contaminated is always a potential problem.Once a land fill operation has been completed the site must be inspected periodically.This land fill is suitable for recreational activities such as parks and play ground.
⭐Incineration:Municipal incinerators burn combustible solid waste and melt certain non combustible materials.Since the high temperature destroys pathogens and their vectors,it is a good method of disposal from health point of view.
⭐Reuse and recycling techniques: Resource recovery is a broad term that is used for the retrieval of valuable materials or energy from a waste.The separating out of materials such as rubber,glass,paper and scrap metal from refuse and reprocessing them for reuse is named as reclamation of waste or recycling.
Paper(54% recovery) can be repulped and reprocessed into recycled paper, cardboard,and other paper products.
Glass(20% recovery)can be crushed, remelted and made into new containers or crushes used as a substitute for gravel or sand in construction materials such as concrete and asphalt.
Some forms of plastics(2.2% recovery) can be remelted and fabricated into carpet fibre,fill for insulated apparel, irrigation drainage,tiles and sheet plastics.
Metals can be melted and fabricated (39% recovery).
Food wastes and yard wastes(leaves,grass etc.) can be composted to produce humus soil conditioner.
Textiles can be shredded and used to strengthen recycled paper products.
