Modelling reactive CAH transport using batch experiment degradation kinetics

Haest, Pieter Jan; Springael, Dirk; Smolders, Erik

doi:10.1016/j.watres.2010.02.031

Cited by 15 publications

(20 citation statements)

References 30 publications

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“…See for example the problems that were encountered by Schaefer et al (2009) (see previous discussion). The spatial and temporal CAH concentrations measured in this experiment were well predicted in a modelling study using batch degradation kinetics (Haest et al, 2010c), i.e. assuming an equal reactivity of the dechlorinators in column as in batch experiments.…”

Section: Column Experimentssupporting

confidence: 56%

The reactive transport of trichloroethene is influenced by residence time and microbial numbers

Haest

Philips

Springael

et al. 2011

Journal of Contaminant Hydrology

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The dechlorination rate in a flow-through porous matrix can be described by the species specific dechlorination rate observed in a liquid batch unless mass transport limitations prevail. This hypothesis was examined by comparing dechlorination rates in liquid batch with that in column experiments at various flow rates (3 -9 -12 cm d -1 ). Columns were loaded with an inoculated sand and eluted with a medium containing 1 mM trichloroethene (TCE) for 247 days. Dechlorination in the column treatments increased with decreasing flow rate, illustrating the effect of the longer residence time. Zero th order TCE or cis-DCE degradation rates were 4-7 fold larger in columns than in corresponding batch systems which could be explained by the higher measured Geobacter and Dehalococcoides numbers per unit pore volume in the columns. The microbial numbers also explained the variability in dechlorination rate among flow rate treatments marked by a large elution of the dechlorinating species' yield as flow increased. Stop flow events did not reveal mass transport limitations for dechlorination. We conclude that flow rate effects on reactive transport of TCE in this coarse sand are explained by residence time and by microbial transport and that mass transport limitations in this porous matrix are limited.

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Section: Column Experimentssupporting

confidence: 56%

The reactive transport of trichloroethene is influenced by residence time and microbial numbers

Haest

Philips

Springael

et al. 2011

Journal of Contaminant Hydrology

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“…This sensitivity analysis shows that the random motility coefficient of Geobacter has an intermediate effect on the model outcome, while the model was most sensitive to the growth parameters Y GEO and c GEO,max and to the kinetic parameters k cell,max and EC 50 . The parameters b i , K s,TCE and k d had a low impact on the model, which is in agreement with our previous findings (Haest et al, 2010b;Philips et al, 2013a). Visualization of the sensitivity of the model towards some of its parameters shows that a factor 4 change in D GEO,0 has a low effect on the modeled TCE concentrations, but has a clear impact on the modeled Geobacter cell densities ( Figure S4A).…”

Section: Modeling Resultssupporting

confidence: 93%

“…. Similarly,Haest et al (2010b) incorporated a reduced dechlorination rate at elevated dechlorinator cell densities in order to describe dechlorination in flow-through columns.…”

mentioning

confidence: 99%

Motile Geobacter dechlorinators migrate into a model source zone of trichloroethene dense non-aqueous phase liquid: Experimental evaluation and modeling

Philips

Miroshnikov

Haest

et al. 2014

Journal of Contaminant Hydrology

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Microbial migration towards a trichloroethene (TCE) dense non-aqueous phase liquid (DNAPL) could facilitate the bioaugmentation of TCE DNAPL source zones. This study characterized the motility of the Geobacter dechlorinators in a TCE to cisdichloroethene dechlorinating KB-1 TM subculture. No chemotaxis towards or away from TCE was found using an agarose in-plug bridge method. A second experiment placed an inoculated aqueous layer on top of a sterile sand layer and showed thatGeobacter migrated several centimeters in the sand layer in just 7 days. A random motility coefficient for Geobacter in water of 0.24 ± 0.02 cm 2 day -1 was fitted. A third experiment used a diffusion-cell setup with a 5.5 cm central sand layer separating a DNAPL from an aqueous top layer as a model source zone to examine the effect of random motility on TCE DNAPL dissolution. With top layer inoculation, Geobacter quickly colonized the sand layer, thereby enhancing the initial TCE DNAPL dissolution flux. After 19 days, the DNAPL dissolution enhancement was only 24% lower than with an homogenous inoculation of the sand layer. A diffusion-motility model was developed to describe dechlorination and migration in the diffusion-cells. This model suggested that the fast colonization of the sand layer by Geobacter was due to the combination of random motility and growth on TCE.

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“…However, recent experimental data provide conflicting evidence as to the relative importance of mobile (pelagic or planktonic) bacteria in biodegradation of chlorinated ethenes (cf. Schaefer et al 2009Schaefer et al , 2010Haest et al 2010). If it becomes clear in the future that mobile bacteria play a significant role in biodegradation of chlorinated ethenes, then the model presented here will need to be amended to account for both stationary and mobile bacteria, perhaps using a method similar to that employed by Clement et al (1998).…”

Section: Transport and Reaction Equationsmentioning

confidence: 99%

Efficient Algorithms for Modeling the Transport and Biodegradation of Chlorinated Ethenes in Groundwater

Mendoza‐Sanchez

Cunningham

2011

Transp Porous Med

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Predicting the fate of chlorinated ethenes in groundwater requires the solution of equations that describe both the transport and the biodegradation of the contaminants. Here, we present a model that accounts for (1) transport of chlorinated ethenes in flowing groundwater, (2) mass transfer of contaminants between mobile groundwater and stationary biofilms, and (3) diffusion and biodegradation within the biofilms. Equations for biodegradation kinetics account for biomass growth within the biofilms, the effect of hydrogen on dechlorination, and competitive inhibition between vinyl chloride and cis-dichloroethene. The overall model consists of coupled, non-linear, partial differential equations; solution of such a model is challenging and requires innovative numerical algorithms. We developed and tested two new numerical algorithms to solve the equations in the model; these are called system splitting with operator splitting (SSOS) and system splitting with Picard iteration (SSPI). We discuss the conditions under which one of these algorithms is superior to the other. The contributions of this paper are as follows: first, we believe that the mathematical model presented here is the first transport model that also accounts for diffusion and nonlinear biodegradation of chlorinated ethenes in biofilms; second, the SSOS and SSPI are new computational algorithms developed specifically for problems of transport, mass transfer, and non-linear reaction; third, we have identified which of the two new algorithms is computationally more efficient for the case of chlorinated ethenes; and finally, we applied the model to compare the biodegradation behavior under diffusion-limited, metabolism-limited, and hydrogen-limited (donor-limited) conditions.

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Modelling reactive CAH transport using batch experiment degradation kinetics

Cited by 15 publications

References 30 publications

The reactive transport of trichloroethene is influenced by residence time and microbial numbers

The reactive transport of trichloroethene is influenced by residence time and microbial numbers

Motile Geobacter dechlorinators migrate into a model source zone of trichloroethene dense non-aqueous phase liquid: Experimental evaluation and modeling

Efficient Algorithms for Modeling the Transport and Biodegradation of Chlorinated Ethenes in Groundwater

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