title: Investigating dominant processes in ZVI permeable reactive barriers using reactive transport modeling.
abstract: The reactive and hydraulic efficacy of zero valent iron permeable reactive barriers (ZVI PRBs) is strongly affected by geochemical composition of the groundwater treated. An enhanced version of the geochemical simulation code MIN3P was applied to simulate dominating processes in chlorinated hydrocarbons (CHCs) treating ZVI PRBs including geochemical dependency of ZVI reactivity, gas phase formation and a basic formulation of degassing. Results of target oriented column experiments with distinct chemical conditions (carbonate, calcium, sulfate, CHCs) were simulated to parameterize the model. The simulations demonstrate the initial enhancement of anaerobic iron corrosion due to carbonate and long term inhibition by precipitates (chukanovite, siderite, iron sulfide). Calcium was shown to enhance long term corrosion due to competition for carbonate between siderite, chukanovite, and aragonite, with less inhibition of iron corrosion by the needle like aragonite crystals. Application of the parameterized model to a field site (Bernau, Germany) demonstrated that temporarily enhanced groundwater carbonate concentrations caused an increase in gas phase formation due to the acceleration of anaerobic iron corrosion.
authors.affiliation: DGFZ e. V., Meraner Str. 10, 01217 Dresden, Germany. aweber@dgfz.de
authors.forename: Anne
authors.initials: A
authors.lastname: Weber
authors.forename: Aki S
authors.initials: AS
authors.lastname: Ruhl
authors.forename: Richard T
authors.initials: RT
authors.lastname: Amos
mesh_terms: D002118:Calcium / Q000737:chemistry; D002119:Calcium Carbonate / Q000737:chemistry; D002254:Carbonates / Q000737:chemistry; D060587:Groundwater; D006843:Hydrocarbons, Chlorinated / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008962:Models, Theoretical; D013440:Sulfides / Q000737:chemistry; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D002254:Carbonates; D006843:Hydrocarbons, Chlorinated; D013440:Sulfides; D014874:Water Pollutants, Chemical; D007501:Iron; D002119:Calcium Carbonate; D002118:Calcium
keywords: Carbonate mineral precipitation; Gas clogging; Permeable reactive barriers; Reactive transport; TCE; Zero valent iron