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Oxygen Release Compound,ORC® pH Levels Moderate pH levels are maintained when ORC is used in bioremediation. In relation to the insoluble nature of ORC, the pH increase remains highly localized. The elevated pH levels are valuable in the control of biofouling as long as they do not migrate downgradient The following field data from the North Carolina site suggests that such migration is minimal or very slow North Carolina Site Oxygen Barrier pH Measurements Day 50'UG ORC t0'DG 25'DG 50'DG 85'DG 7 6 Ili 59 61 6 62 21 59 105 61 65 61 62 49 6 101 6 1 6 6 6.3 709 59 88 57 S9 - 6 137 59 111 61 59 - 6 ote The pH of ORC is on the order of 8 5 and the hydroxide reaction products approach pH 10 In this experiment the y ORC was delivered in a concrete matrix which provides a higher pH as observed in the ORC well-even at these levels there was virtually no migration UG=Upgradient; DG=Downgradient ORC (as Mg02) and CaO2 are both feasible as chemical oxygen sources, however, ORC has a pH which stays more highly localized at the source. Both oxides are converted to the respective hydroxides over time (as oxygen is released) and even larger pH differences are observed The pH of CaO, reaction products can approach 13 while those of ORC stay below 10. Furthermore, since the solubility product of Ca02 is much higher(K.= 5.5 X 10-6) than MgO, as ORC (Ksp = 1.8 X 10-11), the pH will not remain as localized. These differences would be even more pronounced in systems more highly buffered than aquifer water. In buffered soil systems the pH is quite benign with ORC which stays below 8 at concentrations of more than 1% wt./wt Ca02 is difficult to use above .25% wt./wt. and generates a pH of close to I l by the time it is present at 1% wt./wt. REG EN ES IS ---------------------------------------------------------------------------- Sioremediation ParodUcts 27130A Paseo Espada, Ste 1407, San Juan Capistrano, CA 92675 Phone 714-443-3136 Fax 714-443-3140