A mobile mini-plant for the simulation and detection of MIC and biofouling on metals in water circulation systems was developed and tested in laboratory and field experiments. Different metal samples (mild and
stainless steel rings and coupons), arranged in ring columms, were tested for their susceptibility against microbiologically influenced corrosion attack (MIC) and biofouling. Sulfur/-compound utilizing bacteria created aggressive conditions for mild, but not for stainless steel (AISI 304). On mild steel, the electrochemical corrosion process is enforced by the continuous availability of biogenic sulfur/-compounds. Miniaturized sensors for pH and redoxpotential, measuring at the interface metal/biofilm, demonstrated changes in the biofilm due to the
physiological activity of different members in the biofilm consortia. By testing the mini-plant in a field experiment with industrial process water, a biofilm on mild and stainless steel, consisting of sulfate reducing
bacteria (SRB), sulfuric and nitric acid producing bacteria, and manganese oxidizing bacteria developed. In combination with a non-destructive microcalorimetric activity test, the complete equipment can also be used to evaluate biocide efficacy and dosage. Experiments with a commercial biocide demonstrated that microbial activity was inhibited by a dosage of 400 and 600 ppm, but bacteria in the biofilm still survived the biocide attack.