Chlorinated aliphatic hydrocarbons (CAHs), such as trichloroethylene (TCE), are a persistent groundwater pollutant widely distributed in urban areas as a legacy of industrial and dry-cleaner solvent use and are present in approximately 60% of National Priority List sites. Bioremediation can be an effective, low-cost treatments for CAH treatment, however, a significant challenge for these processes involves pH control and high concentrations of CAHs can be toxic to microorganisms carrying out biodegradation. During biological reductive dechlorination of CAHs, build-up of metabolic end products or inadequate system buffering can result in extreme local pH shifts resulting in incomplete contaminant degradation (termed “stuck”) potentially leaving the system in a more hazardous state. Current strategies for regulating pH include additions of chemical buffers or alkaline-generating nutrient substrates, but these may need to be added in commensurate quantities to the contaminant level over extended periods, significantly increasing costs for areas with heavy contamination, natively low pH, or poorly buffered groundwater.<br/>Biofilms and flocs are means by which microorganisms have adapted to hostile environments and extreme pH, thus artificial biofilms or use of encapsulating media to alter the range of conditions for which microbes can function hold substantial promise to address some of these challenge and can be more readily tuned to system requirements. Encapsulation of microorganisms using multiple different polymer matrices have been used in many different applications including degradation of various organic solvents, cometabolic or reductive degradation of TCE, and hybrid biobeads using microorganisms and zero-valent iron and activated carbon for reductive dechlorination of CAHs; however, fundamental CAH mass transfer information is lacking toward developing these engineered materials. To address this knowledge gap, we present effective diffusive permeability measurements using the diaphragm cell method for trichloroethylene (TCE), cis-1,2-dichloroethylene (DCE), vinyl chloride (VC), and protons in poly(vinyl)alcohol/alginate blended hydrogels.

Characterizing effective diffusion of protons, trichloroethylenes and breakdown products in cationic hydrogels

256th National Meeting (2018)

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