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11 <br />I <br />I <br />1 <br />I <br />1 <br />Cl <br />1 <br />tb132 • • <br />J%%g%IJ Pi � l +.��+ .r..+JIII ;J JIJJ, Jr. .r. <br />Page 1 of 1 <br />Moderate pH levels are maintained when ORC is used in bioremediation. In relation to the insoluble <br />nature of ORC, the pH increase remains highly localized. The elevated pH levels control biofouling <br />and they do not migrate downgradient. The following field data from the North Carolina site <br />suggests that such migration is minimal or very slow. <br />North Carolina Site Oxygen Barrier pH Measurements <br />Note: The pH of ORC is on the order of 9.0 and the hydroxide reaction products approach pH 10. In this experiment the <br />ORC was delivered in a concrete matrix which provides <br />es higher <br />gH as observed in the ORC well - even at these levels <br />there was virtually no migration. UG = Upg roti <br />ORC (as M902) and CaO2 are both feasible as chemical oxygen sources, however, ORC has a pH <br />which stays more highly localized at the source. Both oxides are converted to the respective <br />hydroxides over time (as oxygen is released) and even larger pH differences are observed. The pH of <br />le those of ORC stay below 10. FurthermoreX 10, since e <br />Ca02 reaction products can approach 13 whi), <br />solubility product of Ca02 is much higher (K p = 5.5 X 10.6) than M902 as ORC (Ksp = <br />the pH will not remain as localized. <br />nounced in systems more highly buffered than aquifer <br />These differences would be even more pro <br />water. In buffered soil systems the pH is quite benign with ORC which stays below 8 at <br />concentrations of more than 1% wt./wt. Ca02, however, is difficult to use above .25% wt./wt. and <br />generates a pH of close to 11 by the time it is present at 1% wt— <br />/wt- <br />Technical Bulletin hidexIlRegenesis Home Page <br />10:23:01 AM <br />4/23/98 <br />