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Biocorrosion Monitoring System - BIOX -. Dirk Steinmann. Witold Michalowski. Contents. Biocorrosion fundamentals Monitoring devices Electrochemical monitoring system “ BIOX ” Areas of application. Biocorrosion fundamentals. Definition of corrosion:.
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Biocorrosion Monitoring System- BIOX - Dirk Steinmann Witold Michalowski
Contents • Biocorrosion fundamentals • Monitoring devices • Electrochemical monitoring system “BIOX” • Areas of application
Biocorrosion fundamentals Definition of corrosion: Corrosion is the reaction of a material with substances in the environment, which causes a detrimental alteration of the material. It describes the electrochemical, chemical and metallophysical alteration of metals (translated from DIN50900).
Biocorrosion fundamentals Kinds of corrosion processes: Anodic process: Me ⇄ Me2+ + 2 e- Cathodic process: • ½ O2 + H2O + 2 e-⇄ 2 OH- (Oxygen corrosion) • 2 H3O+ + 2 e-⇄ H2 + 2 H2O (Acid corrosion) • H2S + 2 e-⇄ S2- + H2 (H2S corrosion) S2- + Fe2+⇄ FeS
Biocorrosion fundamentals Parameters influencing corrosion: • pH-value • redox-potential • oxygen concentration • water activity All of these corrosion relevant parameters can be influenced by microorganisms leading to the so called biocorrosion. Biocorrosion does not represent a new form of corrosion processes, instead it describes the influence of microorganisms on the kinetics of these processes.
Biocorrosion fundamentals Microorganisms involved: • Acid-producing MO • Inorganic acids: H2SO4(sulfuroxidisers), HNO3(nitrifyers), H2CO3 (heterotrophic organisms) • Organic acids: Acetic acid, formic acid, oxalic acid, citric acid, lichen acids • Sulphate reducing bacteria (SRB) • Most important!! Accounting for 95% of all biocorrosion cases. • Formation of H2S • Metal-depositing bacteria • Formation of Fe2O3 (Iron oxidisers), MnO2 (Manganese oxidisers) • …
BIOXsystem BIOX system is an innovative on-line monitoring tool designed to optimise the antifouling and sanitising water treatments against biofilm growing in industrial cooling circuits, tube networks, pipelines and equipment.
BIOX system • The system “core” consists of a special tubular electrochemical sensor, inserted in suitable ways in plant circuits, which output (electric signal,1 Volt) is correlated both to aerobic biofilm growth and to the presence of oxidant species in the water: • the biofilm growing on metal surface of the sensor • the oxidant species in the water bulk crossing the tubular probe.
ohmic drop measurement water flow in water flow out Stainless Steel - Cathode Zinc - Anode BIOX Probe
Monitoring • The optimal monitoring method should indicate: • Location -Composition • Extend -Kinetics • This information should be acquired: • -on-line -in situ -non destructively • -in real time -accurately -representatively • -reproducibly -automatically • In addition the devices should be easy to handle, robust and cheap. Deposit
BIOX application details High resistance - galvanic coupling • Technique: • Main purpose: • Application: • Environment: • Resolution: • Interferences: • Limits: • Advantages: • Comments: On-line measurements of the microbial fouling growth in the presence of oxidizing species, in particular chlorine and bromine. Laboratory, Pilot: Preliminary test for: Biocide qualification, Water quality qualification, Process water qualification Plant: Biocide treatments optimization Others: Possible application for risk assessment of biofilm and MIC in drinking water and process water Seawater, Fresh water, Industrial water = 0-106 bacteria/cm2 ; = 0-1 mg/l (chlorine) Real time estimation of the biofouling growth, Real time estimation of oxidant presence in the water, Real time (indirect) estimation of chlorine or other oxidant demand of water. Optimization of the consumption of oxidants, with respect to concentration and time. weakly sensitive to Fe++/Fe+++ couple that is present during anticorrosion treatments with ferrous salts. not sensitive to oxidant in the water if biofilm covers the probe; not sensitive to biofilm if high concentration of oxidant in the water; the probe doesn’t work if the flow is absent It does not require skilled personnel in the biological or chemical field, and is easy to handle. The probe must be mechanically cleaned only once a year.
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