Jack is an environmental engineer committed to the challenge of cleaning up China's hazardous waste sites. After working as a consultant in the US and China he decided to pursue a PhD at Tufts University. (He will hopefully be ready to reenter the consulting industry sometime next year.) For his dissertation he is researching best practices for fitting microbial reductive dechlorination (MRD) models to laboratory microcosm experiments as well as how the MRD process can be inhibited by perfluoroalkyl and polyfluoroalkyl substances (PFASs). His website is www.jackelsey.com.
Quantifying Impacts of Microcosm Mass Loss on Kinetic Constant Estimation
Microcosm experiments to assess microbial reductive dechlorination of chlorinated aliphatic hydrocarbons (CAHs) typically experience 5-50% CAH mass loss during the experiment, due to sampling events and reactor component sorption. A literature review, however, reveals that models used to fit experiments generally failed to account for experimental mass loss. To investigate possible resultant bias in best-fit parameters, a series of numerical experiments was conducted by fitting models that did/did not account for mass loss to more than 1300 synthetic datasets, generated using published microcosm data. Models that failed to consider mass loss resulted in significant fitted parameter bias, ranging from 5-45% or 20-120% of the parameter magnitude for experiments with low (10%) or high (40%) mass loss, respectively. These results suggest that failure to properly account for mass loss may lead to inaccurate estimation of kinetic constants and may explain some of the literature-reported variability in these parameters.