SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

Ak r 7 Ion Exchange For Unsaturated Soil: The ion exchange process is a proven method of ■ Extraction removing metals from water. The ground water is Vacuum-Induced Venting pumped through a bed of ion exchange resin,in which the selected ions are exchanged for nonhazardous ions In this process,a vacuum is applied to one or more wells that are chemically attached to the resin. Periodically, in the unsaturated soil,causing air to flow through the the ion exchange resin bed must be regenerated by affected soil and up to the surface to be remediated. FHCs passing a concentrated solution of a nonhazardous and VOCs are removed from the soil by the moving air. salt through the columns. The waste solution may The vapors are drawn to the surface for treatment by a require further treatment or disposal. process such as catalytic oxidation. Ultraviolet Light/Hydrogen Peroxidation ■ Treatment (with air stripping) Catalytic Oxidation This process uses a strong oxidizing agent(usually This process involves "burning" the vapors that are hydrogen peroxide or ozone)and ultraviolet(UV)light released from the contaminated soil. Air that contains to destroy VOCs and FHCs. Ground water is first contaminants is heated,causing the contaminants to be oxi- mixed with the oxidizing agent,then passed through a dized (Figure 5). Oxidation is achieved at much lower tem- chamber in which the treated water is exposed to high peratures than other burning processes by adding a special intensity LtV light(Figure 4). As a result,the toxic material (a catalyst) to the process. This also reduces the compounds are broken down into nontoxic compo- amount of supplemental fuel needed for heating,as well nents such as water and carbon dioxide,and very low as the costs. concentrations of hydrogen chloride. � > � ; Pre-Melo ;GYI eeWIS.Y' TntlM elr P.e '. Hrc ClwnaM GAC eI,XXer MOM ucnenpW' 1 tf r �+ DernleMr r Blovnr Welef epeyere r •. .e C..denuta trap Intuletw C��Xe ContamintleE //////Alr tldrginp wnuoYr .WNbn ground".r in �unX :;M�°n Pump De JMW "...den pump. bnE pSYM.a Ex1YCYE wo ry.Ym 1 vapor tnnnnm wN.r pump Xydroa.nw .iM Air.�pply Chen WeteroN� W.II In uneetur "I Ni.cdon Figure4. UVLight/Oxidation Any remaining contaminants are removed by air Figure 5. Catalytic Oxidation stripping. Because the remaining concentrations are When FHCs are burned,the by-products are water and quite low,the water can be treated by injecting air into carbon dioxide. When chlorinated solvents(such as TICE) the bottom of a tank. The VOCs and FHCs pass into are oxidized,the same byproducts are produced,along the air stream that is then filtered by GAC filters. With extremely low concentrations of hydrogen chloride. If the concentrations of these byproducts are above levels considered safe by the regulatory agencies,a secondary treatment process can be added to further ensure that the treated air is safe. However,because catalytic oxidation is a relatively new technology,it is possible that,based on fur- ther testing,LLNL may substitute another approved tech- nology for it in the future,with regulatory approval.