Chemical oxidation process, site remediation

Introduce the chemical oxidation process, its applicability, limitations, and performance for site remediation involving both soil cleaning and groundwater decontamination. 

When a leaking tank has contaminated a site or an aquifer, or an accidental spill occurs, the only option is remediation, that is, cleaning-up the site or any other environmental space that has been polluted. This remediation will often be performed by applying chemical processes to transform those undesirable substances either on- or off-site (e.g., by normal extraction and treatment techniques) using biochemical reactions with microorganisms, chemical oxidation, stabilization, or other advanced technologies. 

This section introduces the chemical reduction/oxidation process (Redox), its applica-hihty, limitations, and performance for site remediation involving both soil cleaning and groundwater decontamination. Chemical reduction/oxidation (Redox process) chemically converts hazardous contaminants to nonhazardous or less-toxic compounds that are more stable, less mobile, and/or inert. The oxidizing agents most commonly used are ozone, hydrogen peroxide, hypochlorites, chlorine, and chlorine dioxide (50-59). 

Fig. 4. Chemical reduction/oxidation (Redox) process for site remediation (US EPA).

Chemistry. Chemical processes are used to treat water and wastewater, to control air pollution, and for site remediation. These chemical treatments include chlorination for disinfection of both water and wastewater, chemical oxidation for iron and manganese removal in water-treatment plants, chemical oxidation for odor control, chemical precipitation for removal of metals or phosphorus from wastewater, water softening by the lime-soda process, and chemical neutralization for pH (acidity) control and for scaling control. 

In further reference to our previous example, a chemical process for the remediation of perchloroethylene- and trichloroethylene-contaminated sites is the oxidation of these pollutants with potassium permanganate, hydrogen peroxide, or ozone. The final products will be CO2, Cl-, CI2, and H20, which upon reaction will give HCIO and HC1, plus Mn2+ and Mn02 (as byproducts of the permanganate oxidation). Such products represent a much smaller risk (or no risk at all) than the original pollutants. 

---