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Water Usage

Water is an essential element in the production of paper. It is used in large quantities throughout the pulping and papermaking process, inevitably picking up effluents along the way.

Papermakers have been successfully tackling this issue: since 1994, the paper industry has reduced annual water consumption by over 14% per year. To further reduce the environmental impact of the papermaking process, state-of-the-art wastewater treatment installations collect and remove effluents before the water is returned to surface waters or estuaries. The volume of effluents is also reduced by the reuse of processed water and additives.

Interestingly, the net result can often be positive for the environmental quality of the water serving the paper mill. Water taken from rivers or lakes often has to be purified before it can be used and as a result of enhanced treatment techniques, it will be returned in a cleaner state than when it was taken.

Waste water effluents from pulp and paper mills contain mainly solids, nutrients (nitrogen and phosphorus) and organic substances. The concentration of organic substances in effluent water is expressed as the amount of oxygen it takes to degrade these substances through either biological processes (biological oxygen demand - BOD) or chemical reactions (chemical oxygen demand - COD).

Effluents from chemical pulp mills also contain organic chlorine compounds (AOX). This is due to the substances which naturally occur in wood and the paper bleaching process. In the past, chlorine gas was the primary bleaching agent, but chlorine bleaching has now been replaced with more environmentally sound bleaching techniques. These are chlorine dioxide and ozone, resulting in a massive reduction of AOX in the effluents - discharges of AOX have been reduced by more than 90% since 1990.

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