Monitoring of biofouling in papermill process waters

Slime or biofilm formation on paper machine equipment requires costly countermeasures. To provide early detection and efficacy control of countermeasures, deposit formation should be monitored. In this study, a monitoring method was developed based on differential turbidity measurement (DTM). Measurement was performed continuously, on-line, non-destructively and in real time. As reference techniques, automatic pressure drop (PD) measurement and accumulation of biomass on slime boards were used. Both DTM and PD proved to be useful for the measurement of deposit formation on line in the side stream of a paper machine whitewater circuit. With these methods, the efficacy of chemical cleaning procedures and bacteriostatic compounds could be demonstrated, whereas enzymes and nontoxic dispersants turned out to be less effective. The effect of toxic substances confirms the role of vital microbial cells in the formation of the deposits. The use of such substances, which represent a potential hazard to the environment, can be optimized by automated monitoring systems as presented in this study. (C) 2000 Elsevier Science Ltd. All rights reserved.