Water-soil systems, hazardous waste

The EPA Hazardous Ranking System computes a numerical score for hazardous waste. If the score exceeds a predetermined value, the waste site is placed on the National Priority List (NPL) for Superfund cleanup. Discuss the pros and cons of such a ranking system. Describe a possible situation in which an air contaminant is controlled but the control system used transfers the contaminant problem to another medium, such as water or soil. 

Adsorption — An important physico-chemical phenomenon used in treatment of hazardous wastes or in predicting the behavior of hazardous materials in natural systems is adsorption. Adsorption is the concentration or accumulation of substances at a surface or interface between media. Hazardous materials are often removed from water or air by adsorption onto activated carbon. Adsorption of organic hazardous materials onto soils or sediments is an important factor affecting their mobility in the environment. Adsorption may be predicted by use of a number of equations most commonly relating the concentration of a chemical at the surface or interface to the concentration in air or in solution, at equilibrium. These equations may be solved graphically using laboratory data to plot "isotherms." The most common application of adsorption is for the removal of organic compounds from water by activated carbon. 

Alternative final cover systems, such as the innovative evapotranspiration (ET) cover systems, are increasingly being considered for use at waste disposal sites, including municipal solid waste (MSW) and hazardous waste landfills when equivalent performance to conventional final cover systems can be demonstrated. Unlike conventional cover system designs that use materials with low hydraulic permeability (barrier layers) to minimize the downward migration of water from the cover to the waste (percolation), ET cover systems use water balance components to minimize percolation. These cover systems rely on the properties of soil to store water until it is either transpired through vegetation or evaporated from the soil surface. 

Sagar, P.M., Meagher, A., Sobczak, S. Wolff, B.G (1996) Chemical composition and potential hazards of electrocautery smoke. Br. J. Surg., 83, 1792 Sato, A. Nakajima, T. (1979) Partition coefficients of some aromatic hydrocarbons and ketones in water, blood and oil. Br. J. ind. Med., 36, 231-234 Sauer, PA. Tyler, E.J. (1995) Heavy metal and volatile organic chemical removal and treatment in on-site waste water infiltration systems. 1. Catch basirrs and septic tanks. Water Air Soil Pollut., 89, 221-232... 

As discussed in Chapter 3, at least trace amounts of arsenic commonly occur in rocks, soils, sediments, sludges and spent sorbents from water treatment systems, coal ashes, industrial wastes, and many other natural and artificial solids. Depending upon whether they are considered regulatory hazards (Appendix E), solid materials may require treatment before disposal (waste management) or remediation if they are located at a contaminated site. For solids, arsenic treatment may involve reducing the arsenic concentrations in the materials so that they are no longer hazardous (for example, soil washing). However, because arsenic cannot be destroyed, eventually the element will require permanent disposal in a manner that does not... 

Environmental Toxicology Hazardous Waste Incineration Pollution, Air Pollution Control Pollution, Environmental Radioactive Waste Disposal Soil and Groundwater Pollution Transport and Fate of Chemicals in the Environment Waste-to-Energy Systems Waste-water Treatment and Water Reclamation Water Pollution... 

Sampling analysis during this project identified more than 1000 tons/year of soil entering the refinery s underground drainage system. Once there, the solid tends to become oil coated, deposit as sludge in the oil/water separator, and must be handled as listed hazardous waste. At Yorktown, most hazardous waste sludges are recycled to the refinery s coker where hydrocarbons are converted into usable liquid and solid products. A small amount of soil components remains in the coke product. 

Chemical redox is a full-scale, well-established technology used for disinfection of drinking water and wastewater, and it is a common treatment for cyanide (oxidation) and chromium [reduction of Cr(VI) to Cr(III) prior to precipitation] wastes. Enhanced systems are now being used more frequently to treat hazardous wastes in soils. Figure 4 shows a typical site remediation project involving the use of chemical redox (chemical reduction/oxidation) for removal of chromium from the environment (22). 

Incompatible wastes and materials must not be placed in the same pile unless separated or protected by means of a dike, wall, berm, or other device. A hazardous waste may be subjected to land disposal in compliance with RCRA regulations. The landfill must have a liner system to the adjacent subsurface soil or groundwater or surface water. 

Cardiovascular Effects. In humans, oral exposure of intermediate duration to zinc has decreased serum HDL cholesterol levels (Chandra 1984 Hooper et al. 1980). Although this is not a direct effect on the cardiovascular system, the decrease in HDL levels may be associated with an increased risk of coronary artery disease. However, another study showed no effect on HDL levels and a decrease in LDL levels (Samman and Roberts 1988), which would be associated with a decreased risk of coronary artery disease. More information on this effect is presented later in this section under Other Systemic Effects. It is not known if exposure to zinc in air, water, or soil would result in cardiovascular effects in people living near hazardous waste sites. 

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