Modeling Trichloroethene Reduction, Methanogenesis, and Homoacetogenesis in a H 2 -Based Biofilm

Homoacetogenesis and methanogenesis, which usually occur during anaerobic trichloroethene (TCE) dechlorination, affect the removal of TCE and its daughter products. This study develops a one-dimensional, multispecies H2-based biofilm model to simulate the interactions among six solid biomass species [Dehalococcoides, Geobacter, methanogens, homoacetogens, inert biomass (IB), and extracellular polymeric substances (EPS)] and 10 dissolved chemical species [TCE, dichloroethene (DCE), vinyl chloride (VC), ethene, hydrogen (H2), methane, acetate, bicarbonate, utilization associated products (UAP), and biomass associated products (BAP)]. To evaluate and parameterize the model, parameter values from the literature were input into the model to simulate conditions reported for an experiment. The biomass species distribution in the biofilm and the chemical species concentrations in the reactor effluent at a steady state were generally consistent between the experiments and the model. The predicted 15-μm biofilm consisted of three layers, each dominated by a different active biomass type: homoacetogens in the layer next to the membrane, Geobacter in the biofilm surface layer (next to the water), and Dehalococcoides in-between.