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ORC TECHNICAL BULLETIN # IV.2 <br /> Oxygen Release Compound, ORC® <br /> Theoretical Treatment of <br /> Oxygen Distribution in an Aquifer <br /> The movement of oxygen from an ORC particle, to the environment where remediation <br /> takes place, is governed by the laws of mass transport These include Darcy's Law <br /> (Advective Flow) and Fick's Law (Diffusion) In addition, some of the kinetic energy <br /> released when ORC reacts with water can facilitate dispersion <br /> In most cases involving the distribution of oxygen in groundwater, advective flow is <br /> dominant and the distribution of oxygen by this mechanism can be approximated using <br /> flow models. Diffusion is usually a small part of these models, but can become more <br /> important in the result as advection is diminished A pure diffusion model will predict <br /> the distribution of oxygen in a static system. <br /> If contamination is present, as in the case with hydrocarbons, then the distribution of <br /> oxygen in the aquifer is altered for several reasons Not only is oxygen consumed by <br /> microorganisms in the remediation of hydrocarbons, but certain physical phenomenon <br /> effect the movement of oxygen and hydrocarbons differently <br /> To be specific, oxygen distribution patterns are derived through models as a function <br /> of several physical phenomenon including advection, dispersion, retardation and <br /> utilization. Advection is essentially groundwater velocity. Dispersion is a multi- <br /> component phenomenon that involves several forces including groundwater velocity, <br /> dispersivity and diffusion Retardation is a sorbtion phenomenon and utilization relates <br /> to the oxygen consumption by physical and chemical means <br /> Advection essentially effects dissolved phase hydrocarbons and oxygen equally, but its <br /> influence is masked in minimal groundwater velocity systems. Dispersion is partly <br /> composed of diffusion and that can vary with different compounds The diffusion of <br /> oxygen is significantly greater than the diffusion of hydrocarbons in water and an <br /> oxygen front can "catch-up" to a contaminant front Conversely, Retardation can have <br /> a greater effect on contaminants than on oxygen, which essentially has no retardation <br /> coefficient -since it does not stick to surfaces in anon-reactive status _Ujilizalt-on is <br /> 10 what we want It describes the reduction of oxygen as a function of use in remediating <br /> hydrocarbons <br />