Estimating Reaction Rate Coefficients Within a Travel-Time Modeling Framework

Journal Article · Tue Mar 01 04:00:00 EST 2011 · Ground Water

DOI:https://doi.org/10.1111/j.1745-6584.2010.00683.x· OSTI ID:1015088

Gong, R ^[1]; Lu, C ^[1]; Luo, Jian ^[1]; Wu, Wei-min ^[2]; Cheng, H ^[2]; Criddle, Craig ^[2]; Kitanidis, Peter K ^[2]; Gu, Baohua ^[3]; Watson, David B ^[3]; Jardine, Philip M ^[3]; Brooks, Scott C ^[3]

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1. Georgia Institute of Technology
2. Stanford University
3. ORNL

A generalized, efficient, and practical approach based on the travel-time modeling framework is developed to estimate in situ reaction rate coefficients for groundwater remediation in heterogeneous aquifers. The required information for this approach can be obtained by conducting tracer tests with injection of a mixture of conservative and reactive tracers and measurements of both breakthrough curves (BTCs). The conservative BTC is used to infer the travel-time distribution from the injection point to the observation point. For advection-dominant reactive transport with well-mixed reactive species and a constant travel-time distribution, the reactive BTC is obtained by integrating the solutions to advective-reactive transport over the entire travel-time distribution, and then is used in optimization to determine the in situ reaction rate coefficients. By directly working on the conservative and reactive BTCs, this approach avoids costly aquifer characterization and improves the estimation for transport in heterogeneous aquifers which may not be sufficiently described by traditional mechanistic transport models with constant transport parameters. Simplified schemes are proposed for reactive transport with zero-, first-, nth-order, and Michaelis-Menten reactions. The proposed approach is validated by a reactive transport case in a two-dimensional synthetic heterogeneous aquifer and a field-scale bioremediation experiment conducted at Oak Ridge, Tennessee. The field application indicates that ethanol degradation for U(VI)-bioremediation is better approximated by zero-order reaction kinetics than first-order reaction kinetics.

• Research Organization: Oak Ridge National Laboratory (ORNL); Oak Ridge National Environmental Research Park
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1015088
• Journal Information: Ground Water, Journal Name: Ground Water Journal Issue: 2 Vol. 49; ISSN 0017-467X
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AQUIFERS
BIOREMEDIATION
DISTRIBUTION
ETHANOL
MIXTURES
OPTIMIZATION
REACTION KINETICS
SIMULATION
TRANSPORT