Fick's law states that local differences in solute concentration will result in a net flux of solute molecules moving from high concentration regions to low concentration regions.
The Waterloo Emitter emits amendment materials (gas or liquid) via a diffusion mechanism in accordance with Fick's first law. The Waterloo Emitter may be described as a Fickian system whereby a polymeric membrane separates a zone of higher internal concentration (gas or liquid) from a zone of lower external concentration of same species in the groundwater. In mathematical terms, the net amount of material diffusing across a unit cross-section (J, flux) perpendicular to a membrane of known thickness (x) is proportional to the change in concentration (C, higher concentration less lower concentration) divided by the thickness of the membrane. At steady state, Fickian diffusion can be approximated by:
J = D (CWaterlooEmitter - groundwater) / membrane wall thickness
where D is the diffusion coefficient for the membrane material and is expressed in L2 / t.
Note: In gas release applications, mass is released from the tubing on a molecular basis and immediately dissolves in the groundwater thus there are significantly reduced mass transfer limitations compared to commonly used gas sparging (bubbling) techniques
Practical implications for use of the Waterloo Emitter: