David L. Sedlak

Examples of a few research talks and related activities:

Talk on Water Self Sufficiency at Caltech, September 21, 2015.

The Next Generation of Superfund Contaminants, February 25, 2014.

Keynote talk at Clark Prize Conference, November 15, 2014.

Seminar on Perfluorinated Compounds in the Aquatic Environment, Stockholm University, June 24, 2013.

Talk by Doctoral Student Anh Pham on Remediation of Contaminated Groundwater

Ongoing Research

The Fate of Trace Organic Compounds in Treatment Wetlands

Over the past decade, our research group has developed analytical methods for quantifying the extremely low concentrations of organic compounds in municipal wastewater effluent and surface waters.  As an alternative to using advanced treatment methods to remove these compounds, we have been studying the potential for using sunlight and microbes in wetlands to remove the compounds.

We recently developed a new treatment approach that we refer to as an open water unit process wetland.  This system employs a geotextile liner to prevent the growth of rooted plants (i.e, macrophytes) in wetlands.  The open water allows for photochemical transformation of compounds while a layer of microbes that accumulates above the liner causes the breakdown of the compounds.  The open water wetland removes trace organic contaminants more efficiently than many of the existing vegetated wetlands and has proven to be an effective tool for protection of aquatic habitats and potable water reuse projects.   

Read more about the open water unit process wetland.

In Situ Chemical Oxidation of Persistent Organic Contaminants

See Video Contaminant oxidation by activation of persulfate and hydrogen peroxide

See Video Hydrogen peroxide activation by iron minerals for groundwater treatment

Over the past decade, the use of hydrogen peroxide (H2O2) for in situ remediation of contaminated groundwater and soil has become increasingly popular. In this remedial practice, concentrated solutions of hydrogen peroxide sodium persulfate are injected into groundwater or are added to soil.  Upon contact with iron- and manganese-containing minerals, the oxidants are converted into hydroxyl radical and sulfate radical.  The technology is simple, easy to deploy, and effective against many contaminants normally encountered at hazardous waste sites (e.g., benzene, trichloroethylene, or polycyclic aromatic hydrocarbons). The disadvantage of using hydrogen peroxide has a very short lifetime in the subsurface, meaning that it may be consumed before it reaches contaminated zones. Persulfate offers an attractive alternative, but its reactions with minerals and organic contaminants are not well understood.  In this project, we are unraveling the complex chemistry of oxidants under conditions encountered in remediation systems.

Read more about this project here.