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ORC TECHNICAL BULLETIN # IVA <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 blofouling 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 10' DG 25' DG 50' DG 85' DG <br /> 7 6 113 59 61 6 62 <br /> 21 59 105 61 65 6I 62 <br /> 49 6 101 61 6 6 63 <br /> 709 59 88 57 59 - 6 <br /> 137 59 111 61 59 - 6 <br /> Note The pH of ORC is on the order of 8 5 and the hydroxide reaction products approach pH 14 In this experiment the <br /> ORC was delivered m 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 (K5p = 5 5 X 10-6) thanM902 as ORC (KSP = 1 8 X 10-"), 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 /> REGENESIS -_.._......________________..___.._________________..___........_......_____________..______ <br /> Bioremediation Products 27130A Paseo Espada, Ste 1407, San Joan Capistrano, CA 92675 <br /> Phone 714-443-3136 Fax 714-443-3140 <br />