Laserfiche WebLink
l� 1996 10:3HAM—"6103666661 N0, 9364 F, 40 <br /> tbl32 • • <br /> Page 1 of 1 <br /> 1 e <br /> J �= l :� yt�' r's �: � . :.1 . � r. LttJJJt� J , Jr.o <br /> eve s <br /> Moderate pH levels are mz.intained 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 biofouhng <br /> and they do not migrate downgradient. The following field data from the North Carolina site <br /> suggests that such migratic;n is minimal or very slow. <br /> Norte Carolina Site Oxygen Barrier pH Measurements <br /> a <br /> T J. ' <br /> o <br /> �. <br /> Note:The pH of ORC is on the 3rder of 9.0 and the hvdmxide reaction products approach pH 10_In this experiment the <br /> O 7 was d6vered in a concrete matrix which provides a higher pH as observed in the ORC well•even at these levels <br /> there was virtually no migrationt UG=Upgradient;DG-Downgradient <br /> l <br /> r ORC (as MgOi) and CaOz are both feasible as chemical oxygen sources,however, ORC has a pH <br /> which stays more highly]ccalized 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 /> CaO;reaction products cart approach 13 while those of ORC stay below 10. Furthermore, since the <br /> r solubility product of Ca02;is much higher(K,p = 5.5 X 10.6)than MS02 as ORC (K.y = 1.8 X 10.1 t), <br /> a the pH will not remain as localized. <br /> J hese differences would bia even more pronounced in systems more highly buffered than aquifer <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. CaOz, however, is difficult to use above .25%wt.iwt. and <br /> generates a pH of close to 11 by the time it is present at 1% wt./wt. <br /> I <br /> Technical Bulletin IndexilRegenesis Home Page <br /> 1 <br /> 4'23198 ! 10:23:01 AM <br />