Monitoring of biofouling in papermill process waters

Slime or biofilm formation on paper machine equipment requires costly count ermeasures. To provide early detection and efficacy control of countermeasu res, deposit formation should be monitored. In this study, a monitoring met hod was developed based on differential turbidity measurement (DTM). Measur ement was performed continuously, on-line, non-destructively and in real ti me. As reference techniques, automatic pressure drop (PD) measurement and a ccumulation 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 str eam of a paper machine whitewater circuit. With these methods, the efficacy of chemical cleaning procedures and bacteriostatic compounds could be demo nstrated, whereas enzymes and nontoxic dispersants turned out to be less ef fective. The effect of toxic substances confirms the role of vital microbia l cells in the formation of the deposits. The use of such substances, which represent a potential hazard to the environment, can be optimized by autom ated monitoring systems as presented in this study. (C) 2000 Elsevier Scien ce Ltd. All rights reserved.