Biocorrosion Monitoring System - BIOX -

Witold Michalowski

Dirk

Steinmann

Contents

(1)Biocorrosion fundamentals

(2)Monitoring devices

(3)Electrochemical monitoring system “BIOX”

(4)Areas of application

Biocorrosion fundamentals

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).

Definition of corrosion:

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 fundamentalsParameters 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 fundamentalsMicroorganisms 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)

…

Biocorrosion fundamentals

BIOX system 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 systemThe 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.

BIOX Probe

Stainless Steel - Cathode

Zinc - Anode

water flow outwater flow in

ohmic drop measurement

The Industrial BIOX system

MonitoringThe 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

1) Technique:

2) Main purpose:

3) Application:

4) Environment:

5) Resolution:

6) Interferences:

7) Limits:

8) Advantages:

9) Comments:

High resistance - galvanic coupling

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 qualificationPlant: Biocide treatments optimizationOthers: 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) 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

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.

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.

Have a nice Day!!!

Thank you for paying attention!!!