Microbially enhanced dissolution and reductive dechlorination of PCE by a mixed culture: Model validation and sensitivity analysis

Abstract

Reductive dechlorination catalyzed by organohalide-respiring bacteria is often considered for remediation of non-aqueous phase liquid (NAPL) source zones due to cost savings, ease of implementation, regulatory acceptance, and sustainability. Despite knowledge of the key dechlorinators, an understanding of the processes and factors that control NAPL dissolution rates and detoxification (i.e., ethene formation) is lacking. A recent column study demonstrated a 5-fold cumulative enhancement in tetrachloroethene (PCE) dissolution and ethene formation to ethene, as well as column length and flow rate (i.e., column residence time). If cis-DCE 3 inhibition was neglected, the model over-predicted ethene production nine fold, while reductions in residence time (i.e., a two-fold decrease in column length or two-fold increase in flow rate) resulted in a more than 70% decline in ethene production. These results demonstrate that spatial and temporal microbial community dynamics and activity must be understood to model, predict, and manage bioenhanced NAPL dissolution.

Relative contribution of set cathode potential and external mass transport on TCE dechlorination in a continuous-flow bioelectrochemical reactor

“…On the other hand, it cannot be excluded that at 0.9 mL min À1 , due to the substantially higher TCE load applied to the reactor, cis-DCE dechlorination to VC was slightly inhibited by TCE, since this latter compound was only partially removed. Indeed, the inhibitory effect of higher chlorinated ethenes on the dechlorination of lesser chlorinated ethenes has been commonly reported in the literature (Yu and Semprini, 2004;Chen et al, 2013).…”

Natural attenuation model and biodegradation for 1,1,1-trichloroethane contaminant in shallow groundwater

“…The experimental columns( Chen et al, 2013 ), which were sterilized before usage, were designed to simulate the contaminated groundwater and assess the effectiveness of natural attenuation of TCA. The influent solution was continuously pumped from the influent reservoir, a modified 6 L borosilicate glass vessel with an N 2 pocket, to the bottom of the column via a peristaltic pump.…”

Numerical modeling analysis of hydrodynamic and microbial controls on DNAPL pool dissolution and detoxification: Dehalorespirers in co-culture

“…When biodegradation reduces contaminant concentrations at the DNAPL-water interface, the driving force for contaminant dissolution from NAPL source zones is increased, relative to abiotic dissolution processes. Modeling studies [14][15][16][17][18][19][20][21] have demonstrated the potential for biodegradation-enhanced NAPL dissolution to decrease the longevity of NAPL source zones.…”

“…Importantly, because of significant differences in the dehalorespiration kinetics exhibited by different dehalorespiring strains, the extent to which bioenhanced dissolution was observed depended largely on the dehalorespiring population that was dominant at the DNAPL-water interface. Chen et al [16] used the column data of Amos et al [29] to develop and test a one-dimensional model incorporating two dechlorinating populations, one of which reductively dechlorinates PCE to DCE (Geobacter lovleyi strain SZ) and a second population of Dehalococcoides mccartyi strains that dechlorinates DCE to ethene.…”