Bacteriological Water Quality of Pulp and Paper Mill Effluents: The Problem of Klebsiella Pneumoniae, 1992 Environmental Conference Proceedings

It has long been recognised that pulp and paper mill effluents can contain very high concentrations of Klebsiella pneumoniae. Many strains are thermotolerant and can be detected as both total and faecal coliforms in enumeration tests. This can represent a problem where the mill effluent is discharged to receiving waters which are classified with a bacteriological water quality standard, with maximum concentrations for total or faecal colifoims. Some pulp mills have been required to reduce the bacterial concentrations in their effluents in order to comply with these numerical standards. This paper reviews the significance of K. pneumoniae in pulp mill effluents, in terms of its public health significance, implications for compliance with water quality standards, and the effects of effluent treatment systems on bacterial numbers. The approach to this issue by different countries with significant pulp and paper industries is also reviewed. The results of a detailed bacteriological evaluation of a New Zealand thermomechanical pulp mill effluent are described, and alternative indicator organisms are suggested, having regard to recent changes in bacteriological water quality guidelines promulgated by the US Environmental Protection Agency.