Hazardous waste disposal refers to the safe and controlled management of wastes that possess characteristics such as toxicity, flammability, corrosivity, reactivity, or infectiousness. Improper disposal of hazardous waste can contaminate soil, water and air and may cause serious risks to human health and the environment. Therefore, hazardous waste must be treated and disposed of according to its physical and chemical characteristics. One important method is landfill disposal. Hazardous wastes that cannot be reused or recovered may be placed in specially designed hazardous waste landfills. These landfills have engineered liners, leachate collection systems, monitoring wells and protective covers to prevent harmful substances from entering soil and groundwater. Waste is usually treated or stabilized before being placed in the landfill. Ordinary municipal dumping grounds should not be used for hazardous waste because they do not provide adequate containment. Incineration is another widely used disposal method. In this process, hazardous waste is burned at very high temperatures in specially designed incinerators. It is particularly suitable for combustible organic wastes, certain chemical wastes and infectious