Examining Removal of Toxic Chemicals in Wastewater Stabilization Ponds
Helen Sanchez
Mentor: Stanley Grant
A wastewater stabilization pond is a relatively shallow body of wastewater contained in an earthen basin, which is designed to treat wastewater. Advantages of this type of treatment system include its low cost, low energy usage, and long-term sustainability. Relative to treating urban runoff, wastewater stabilization ponds can eliminate toxic pollutants through a variety of physicochemical processes, including sedimentation, filtration, solar ultraviolet disinfection, denitrification, plant uptake, and volatilization. In this study, we will measure the size distribution and sedimentation rate of particles as dry weather runoff flows through a wastewater stabilization pond operated by the Irvine Ranch Water District (IRWD). These measurements will be carried out with a low-angle light scattering instrument (Sequoia LISST-100ST) that can measure particle size and sedimentation velocity over 32 size bins, ranging from 2.5 to 500 microns. Water samples will be collected from the influent and effluent to the wetland, placed on ice in the dark, and transported back to Dr. Grant’s lab within a 6-hour period to analyze them with the LISST-100ST. The data obtained from the LISST-100ST will be coupled with simple residence time modeling of the wetland to determine the extent to which toxic chemicals associated with particles in urban runoff are removed as they flow through IRWD’s wastewater stabilization pond.