Recent Changes in the Prevalence and Causes of Bulking Filamentous Bacteria in Pulp and Papermill Activated Sludge Systems, 1997 Environmental Conference Proceedings

The prevalence of filamentous bacteria types as a cause of ulking in pulp and papermill activated sludge systems has hown a significant change in the past several years, as ompared to findings of 10 years previous. A survey of ilamentous bulking problems at 80 U.S. and Canadian pulp and apermills conducted in 1996 showed the five most prevalent ilaments to be Thiothrix I and II, Nostocoida limicola II, type 914, and Haliscomenobacter hydrossis, each accounting for 0% or more of bulking episodes. Causes for filamentous ulking and their percent contribution to bulking episodes xamined were high organic acid concentration (septicity)-68%; ower F/M operation-lo%; low nitrogen and/or hosphorus-13%; and low oxygen concentration-9%. This ontrasts to the findings for 10 years previous where the major auses of filamentous bulking were low F/M operation-49%; ow oxygen concentration-22%; septicity-21%; and low utrients-8%.

These changes in filament prevalence and causes are a result of ignificant changes in pulp and papermill processes in recent yars that have altered wastewater characteristics. The two most significant changes have been the widespread processing of recycle fiber and reduced chlorine use as a bleaching agent.