Novel method for creating biocides from process waters

Electrochemical generation of oxidants was studied to find new solutions to control microbial contamination in process waters. The approach was to generate the biocides directly from the process without any chemical additions. Laboratory trials indicated that the direct electrolysis of process waters was an efficient new concept to control microbial contamination at paper mills. Electrolysis considerably reduced the need of halogen containing biocides, thus lessening risk of corrosion. Instead of increasing halogen concentration like with the conventional stabilized halogen biocide systems, the electrolysis concept was able to decrease the concentration of halogen in the process waters. At the same time the conductivity of the process waters decreased indicating process purifying effect. The trials with samples from paper machines indicated that the new concept can be applied into several process stages. In addition to killing effect the electrolysis was able to produce excess amount of oxidants which turned contaminated process water into biocide. This technology enables on-site biocide production which eliminates all transportation costs, risk associated with storage of hazardous chemicals and biocide lost due to degradation. Biocidal effects together with reduction in amount of halogen containing oxidants and reduction in process conductivity make this concept economically attractive and environmentally positive.