A new dual biocide concept for fine papermaking

Electrochemical generation of oxidants was studied to find new solutions to control microbial contamination at paper mills. Laboratory and semi-pilot trials using a Wet End Simulator indicated that the combination of an electrochemically produced halogen-containing oxidant and percarbonate was an efficient new biocide concept, especially in fine papermaking. Addition of percarbonate considerably reduced the need of halogen containing biocides, thus lessening risk of corrosion. The trials with samples from fine paper machines indicated that the new concept required halogenated biocides to be dosed first, and the time delay between additions of biocide needed to be sufficient to ensure that no residual halogen left when percarbonate was added. Electrochemical generation enables on-site biocide production which decreases transportation cost, risk associated with storage of hazardous chemicals and biocide lost due to degradation. Thus, on-site generation of biocides together with potential reduction in amount of halogen containing oxidants make this dual concept economically attractive and environmentally positive.