Technical Bulletin No. 0168: Effect of Fiber on the Dewatering of Paper Mill Sludges by Vacuum Filtration

Variable results are frequently obtained when sludges produced on clarifying paper mill effluents are dewatered by vacuum filtration. This variability has frequently been attributed to changes in concentration of long fiber in the slurry being dewatered, but little specific information regarding the actual effects was found in the literature. Because of this, the investigation first reported in 1963 in the attached technical bulletin was made by the Central-Lake States Regional Center of the National Council. Results of this study indicated that drainage time is reduced significantly by small additions of fiber, but that loading rates were not greatly affected. Solids retention, as well as cake removal, also improved on addition of fiber to the sludges tested. Freeness of the added fiber appeared to have little influence on the overall operation.