title: Monitoring of microbially mediated corrosion and scaling processes using redox potential measurements.
abstract: The use of redox potential measurements for corrosion and scaling monitoring, including microbially mediated processes, is demonstrated. As a case study, monitoring data from 10years of operation of an aquifer thermal energy storage (ATES) site located in Berlin, Germany, were examined. (Fe(2+))-activities as well as [Fe(3+)]-build up rates were calculated from redox potential, pH, conductivity, temperature and dissolved oxygen measurements. Calculations are based on assuming (Fe(3+))-activity being controlled by Fe(OH)3-solubility, the primary iron(III)-precipitate. This approach was tested using a simple log-linear model including dissolved oxygen besides major Fe(2+)-ligands. Measured redox potential values in groundwater used for thermal storage are met within ±8mV. In other systems comprising natural groundwater and in heating and cooling systems in buildings, quantitatively interpretable values are obtained also. It was possible to calculate particulate [Fe(3+)]-loads in the storage fluids in the order of 2μM and correlate a decrease in filter lifetimes to [Fe(3+)]-build up rates, although observations show clear signs of microbially mediated scaling processes involving iron and sulphur cycling.
authors.affiliation: Leuphana University of Lueneburg, Institute for Sustainable and Environmental Chemistry, Scharnhorststrasse 1/13, 21335 Lueneburg, Germany. Electronic address: opel@uni.leuphana.de.
authors.forename: Oliver
authors.initials: O
authors.lastname: Opel
authors.affiliation: Leuphana University of Lueneburg, Institute for Sustainable and Environmental Chemistry, Scharnhorststrasse 1/13, 21335 Lueneburg, Germany.
authors.forename: Tanja
authors.initials: T
authors.lastname: Eggerichs
authors.affiliation: Leuphana University of Lueneburg, Institute for Sustainable and Environmental Chemistry, Scharnhorststrasse 1/13, 21335 Lueneburg, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Otte
authors.affiliation: Leuphana University of Lueneburg, Institute for Sustainable and Environmental Chemistry, Scharnhorststrasse 1/13, 21335 Lueneburg, Germany.
authors.forename: Wolfgang K L
authors.initials: WK
authors.lastname: Ruck
mesh_terms: D003343:Corrosion; D005290:Ferric Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D012995:Solubility; D013696:Temperature; D014871:Water Microbiology
chemical_list: D005290:Ferric Compounds; D010100:Oxygen
keywords: Aquifer; Corrosion; Redox potential; Scaling; Thermal systems