Risk assessment for the hazardous waste management

Risk assessment is done to make the characterization of the potential adverse effects of human exposure, to environmental hazards. It is a tool for understanding the health and environmental hazards associated with hazardous waste and can improve the basis upon which to make such waste management decisions.

Risk may be defined as the probability of suffering harm or loss when the resulting harm is measurable. The hazard posed by a waste is a function of it' s toxicity, mobility ,it's persistence and also how it is contained. The human health risk assessment includes carcinogenic and non-carcinogenic risks to all receptors exposed to hazardous chemicals of the environment.

The introduction of chemicals into an ecosystem can provide a direct hazard to individual organisms, or may affect their ability to reproduce. It can affect the overall structure and function of an ecosystem or it's components.

Potentially exposed population should be considered in management of waste-:

Present and future population in vicinity of the site .
Sub-population of special concern e.g.young children in the case of lead contamination.
Potential on-site workers during any redemption.
What sort of sensitive public facilities are located near the site e.g. schools, hospitals, day care centre, nursing homes etc.
What outdoor activities occur e.g. parks, play ground etc.
What fraction of time do various sub-population spend in potentially contaminated area e.g. children in grade school.
What secondary exposures are possible e.g. contamination of crops at nearby farm.

Treatment methods for hazardous wastes include biological treatment, neutralization, oxidation-reduction, precipitation, carbon absorption, ion exchange, reverse osmosis, fixation/stabilization, and incineration.

After various treatment method ,there will always remain some residue to be disposed off. Land disposal techniques include landfills , surface impoundment's underground injection wells, and waste piles. Wastes should not be mixed.The location of each cell of different wastes should be clearly identified in a locator map or similar means. Surface impounments are excavated to store liquid hazard waste. Injection wells are used as a cheap method of disposing hazardous waste; They should be located well below drinking water aquifers.Unless these wastes are innocuous before disposal, they are like time bombs waiting to explode at the right moment.

Waste piles are non-containerized accumulation of solid wastes used for temporary storage. Research must be made to find economical ways that will render hazardous waste harmless before being put in their final resting place.