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ORG 1-tGHNIGAL BULLETIN # IVA I - <br /> Oxygen Release Compound,ORC® <br /> pH Levels <br /> Moderate pH levels are maintained when ORC is used in bioremediation. In relation <br /> to the insoluble nature of ORC, the pH increase remains highly localized. The elevated <br /> pH levels are valuable in the control of biofouling as long as they do not migrate <br /> downgradient. The following field data from the North Carolina site suggests that such <br /> migration is minimal or very slow. <br /> North Carolina Site Oxygen Barrier pH Measurements <br /> Day 50'UG ORC l0'DG 25'DG 50'DG 85'DG <br /> 7 6 11.3 5.9 6.1 6 6.2 <br /> 21 5.9 10.5 6.1 6.5 6.1 6.2 <br /> 49 6 10.1 6.1 6 6 6.3 <br /> 709 5.9 8.8 5.7 5.9 - 6 <br /> 137 5.9 11.1 6.1 5.9 - 6 <br /> Note: The pH of ORC is on the order of 8.5 and the hydroxide reaction products approach pH 10. In this experiment the <br /> ORC was delivered in a concrete matrix which provides a higher pH as observed in the ORC well-even at these levels there <br /> was virtually no migration.UG=Upgradient; DG=Downgradient <br /> ORC (as M902) and Ca02 are both feasible as chemical oxygen sources, however, ORC <br /> has a pH which stays more highly localized at the source. Both oxides are converted to <br /> the respective hydroxides over time (as oxygen is released) and even larger pH <br /> differences are observed. The pH of Ca02 reaction products can approach 13 while <br /> those of ORC stay below 10. Furthermore, since the solubility product of Ca02 is much <br /> higher(Ksp= 5.5 X 10') thanMg02 as ORC (Ksp = 1.8 X 10-11), the pH will not remain <br /> as localized. <br /> These differences would be even more pronounced in systems more highly buffered <br /> than aquifer water. In buffered soil systems the pH is quite benign with ORC which <br /> stays below 8 at concentrations of more than 1% wt./wt. Ca02 is difficult to use above <br /> .25% wt./wt. and generates a pH of close to 11 by the time it is present at 1% wt./wt. <br /> RE G E N ES I S ----------------------------------------------------------------------------- <br /> Bioremediation Products 27130A Paseo Espada, Ste 1407, San Juan Capistrano, CA 92675 <br /> Phone: 714-443-3136 Fax: 714-443-3140 <br />