Incorporation of aqueous reaction kinetics and biodegradation intoTOUGHREACT: Application of a multi-region model to hydrobiogeoChemicaltransport of denitrification and sulfate reduction

Journal Article · Thu Jul 13 04:00:00 EDT 2006 · Vadose Zone Journal

OSTI ID:932471

Xu, Tianfu

The need to consider aqueous and sorption kinetics andmicrobiological processes arises in many subsurface problems. Ageneral-rate expression has been implemented into the TOUGHREACTsimulator, which considers multiple mechanisms (pathways) and includesmultiple product, Monod, and inhibition terms. This paper presents aformulation for incorporating kinetic rates among primary species intomass-balance equations. The space discretization used is based on aflexible integral finite difference approach that uses irregular griddingto model bio-geologic structures. A general multi-region model forhydrological transport interacted with microbiological and geochemicalprocesses is proposed. A 1-D reactive transport problem with kineticbiodegradation and sorption was used to test the enhanced simulator,which involves the processes that occur when a pulse of water containingNTA (nitrylotriacetate) and cobalt is injected into a column. The currentsimulation results agree very well with those obtained with othersimulators. The applicability of this general multi-region model wasvalidated by results from a published column experiment ofdenitrification and sulfate reduction. The matches with measured nitrateand sulfate concentrations were adjusted with the interficial areabetween mobile hydrological and immobile biological regions. Resultssuggest that TOUGHREACT can not only be a useful interpretative tool forbiogeochemical experiments, but also can produce insight into processesand parameters of microscopic diffusion and their interplay withbiogeochemical reactions. The geometric- and process-based multi-regionmodel may provide a framework for understanding field-scalehydrobiogeochemical heterogeneities and upscaling parameters.

• Research Organization: Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
• Sponsoring Organization: USDOE Director, Office of Science
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 932471
• Report Number(s): LBNL--61086; BnR: YN0100000
• Journal Information: Vadose Zone Journal, Journal Name: Vadose Zone Journal Vol. 7
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
Aqueous reaction kinetics Bacterial growth TOUGHREACTMulti-region model Reactive Transport Denitrification SulfateReduction
BIODEGRADATION
COBALT
DENITRIFICATION
DIFFUSION
KINETICS
MASS BALANCE
NITRATES
REACTION KINETICS
SIMULATION
SIMULATORS
SORPTION
SULFATES
TRANSPORT
WATER