Overview of Improvements in Effluent Quality as a Result of Changes to the Federal and Provincial Pulp and Paper Mill Effluent Control Regimes

摘要

In May 1992, the Canadian federal government introduced a comprehensive regulatory framework to address pulp and paper mill discharges. The r992 federal regulatory framework replaced an earlier set of pulp and paper regulations that had been passed under the Fisheries Act in 1971. The new framework consisted of two regulations under Canadian Environmental Protection Act (CEPA) and one under the Fisheries Act.Under CEPA, the Pulp and Paper Mill Defoamer and Wood Chips Regulations set quantitative limits on the amounts of unchlorinated dioxin and furan molecules allowed in defoamers. As well, they banned the use of wood chips derived from chlorophenolic treated lumber in pulp mills. The Pulp and Paper Mill Chlorinated Dioxins and Furans Regulations prohibited the release of measurable concentrations of 2,3,7,8 chlorinated dioxin and furan in effluent from mills that use chlorine or chlorine dioxide to bleach pulp. These regulations minimized the entry of dioxin-furan precursors into the pulping process and induced major reductions in the amounts of gaseous chlorine that could be used in the bleaching processes.Under the Fisheries Act, the Pulp and Paper Effluent Regulations (PPER) set discharge limits for BOD matter and total suspended solids (TSS). As well, the PPER prohibited the discharge of effluents that are acutely lethal to rainbow trout at 100% effluent. These limits were more stringent than those included in the 1971 regulations. In addition, the PPER included a requirement for all mills to conduct Environmental Effects Monitoring studies to determine the impact of their effluents in the receiving waters.In parallel with the federal government, the provinces of British Columbia, Ontario and Quebec updated their regulations and Alberta updated their permits to address effluent quality from pulp and paper mills. All the provincial limits were equal or more stringent than the federal limits.Compliance with the federal and provincial requirements entailed major changes in the way effluents were treated by the industry, requiring in most cases the installation of secondary (biological) treatment plants. The new regulations and permitting have led to vast improvements in effluent quality at all pulp and paper mills. Releases of BOD, TSS, adsorbable organic halides, and chlorinated dioxins and furans have been significantly reduced compared to preregulatory levels. These improvements have arisen as a result of the pollution prevention measures taken to address the bleach plant areas as well as the introduction of secondary biological treatment at most mills. This paper outlines that nature and effect of these changes on effluent quality over time.