Polyacrylamide (PAM) zur Prozesswasserbehandlung am Beispiel holzhaltiger Druckpapiere

Measures for fiber recovery and lowest load of circulating water and clear filtrates have major impact on productivity and paper quality. Well known technologies (Dissolved Air Flotation, Disk Screens) are supported by tailor-made chemical additives. At this flocculants are used on the basis of polyacrylamides (PAM) possibly in combination with coagulants such as polyamines or poly-DADMAC. Chemistry and market situation of this flocculants will be introduced in this paper. Process Water Treatment will be discussed considering the production of mechanical printing papers as example. After an explanation of the water circuitry feeding points and dosages will be described. Finely it will be shown, that more then 99 % of the flocculants are carried out with the rejects. Ca. 0,5 % only will be discharged to the biological treatment plant (which belongs to the municipality in this case). In this plant significant higher amounts ofsimilar polyacrylamides are added for sludge dewatering according best technical practice.