Laboratory simulator for splash zone biofouling and corrosion in paper machine environment

A novel laboratory simulator developed for pitting studies in chlorine dioxide bleaching was modified to investigate the effects of microbe containing environments in the splash zones of paper and board machines. Layers of dried chemical pulp were used to simulate deposits in splash zones. Artificial white water was prepared using as main components stone groundwood (sgw) and chemical pulp transferred from a paper machine. A consortium of aerobic as well as anaerobic bacteria typical for paper and board machine environments was used. Biofilm formation and the electrochemical behavior of stainless steel were studied. Open circuit potentials were recorded and polarization measurements were performed. The biofilms formed were analyzed by microbial cultivation and by epifluorescence microscopy. Sulfur compounds as well as the chloride and oxalate contents of the artificial white water in the course of the experiments were analyzed using capillary electrophoresis. Also some of the layers of chemical pulp closest to the metal surface were analyzed after the test. The results showed that the developed laboratory simulator was a valuable and versatile tool for studying the microbiological and chemical effects on pitting corrosion of stainless steel in conditions simulating the splash zone areas of paper and board machines.