Pulp and paper technical guidance: criteria and guidance for pronounced eutrophication, chapter 1

Historical Overview

Historically, in Canada, mill effluents contained many substances able to cause deleterious effects in receiving waters. While the effects at individual sites varied according to the quantity of discharges and the dilution capacity of the receiving waters, problems seen at some sites included large areas of rotting fibre mats combined with large reaches of water with little or no dissolved oxygen, and concentrations of effluent constituents toxic to fish, even after dilution.

The Pulp and Paper Effluent Regulations (PPER), which were passed in 1992, set strict limits for BOD (biochemical oxygen demand) and TSS (total suspended solids), based on the performance of Canadian mills using secondary treatment and prohibited the discharge of acutely lethal effluent. The PPER are effluent quality based regulations and thus the performance expectation was that each mill would achieve the minimum national standards for effluent quality. However, it was recognised that the level of protection needed could vary depending on the type of ecosystem into which the regulated facility discharged its effluent. As a result, the EEM program was introduced, which assesses the impacts of the effluent on the receiving environment and helps to assess if these effluent quality based regulations are achieving adequate protection.

Over the past three decades, vast improvements in pulp and paper effluent quality have occurred as a result of mills installing pollution prevention measures and, in most cases, secondary treatment, to meet federal and provincial requirements. The pulp and paper industry has taken action and made major capital and human resource investments to achieve these improvements. Between 1970 and 2003, BOD deposits per tonne of output fell by 98%, TSS deposits by 92% and effluent discharges per tonne of output by 59%. The toxicity of effluents also changed from being acutely lethal to fish at low concentrations to being essentially non acutely lethal in whole effluents. In 2003, over 96% of effluent samples tested passed the non acutely lethal requirements.