Chemical Volatilization from Shallow Liquid Waste Impoundments
and Water Bodies
Research Team: Yoram Cohen (PI), Francesc Giralt (co-PI), Xavier Grau (co-PI), Ildefonso
Cuesta (Research Scholar).
The volatilization of contaminants from liquid waste impoundments under natural conditions
is being investigated using a three-dimensional turbulent fluid flow/mass transfer model. The
three-dimensional Navier-Stokes equations coupled with the energy and species mass conservation
equations are solved (for both laminar and turbulent conditions) to yield the fluid flow and
concentration fields resulting from chemical volatilization under the action of wind shear and due to
free-convection. Initial simulations in ponds of depth:length ratio of 1:4 and 1:10 revealed that
recirculating regions that are confined to the down-wind end of the liquid ponds can exist. Thus, the
concentration field can be highly non-uniform. This has significant implications to the design of
sampling protocols for liquid waste impoundments as well as shallow natural water bodies. Initial
simulation revealed that, at low wind speeds, the mass transfer coefficients can be significantly lower
than estimates derived from standard correlations which are based on experiments in well-mixed
water bodies. Current work focuses on evaluating the effect of pond geometry, wind speed, solar
radiation, and chemical mass diffusivities. While the initial simulations focused on low wind speeds
and laminar flow in the ponds future work will be expanded to include the use of a -î type
turbulent model and also a large-eddy simulation. This research project will result in an improved
ability to estimate VOC emissions from liquid waste impoundments and chemical exchange rates at
the atmosphere/water interface for shallow natural water bodies.