Operational monitoring of Glomma – discharges from Borregaard

Summary

In autumn 2008, Borregaard had to close its aerobic treatment plant due to the risk of Legionella infection. As a result there has been an increase in the discharges of readily available organic matter into the River Glomma. Previous studies have shown that the discharges of readily available organic material from Borregaard have caused a proliferation of the filamentous bacterium, Sphaerotilus natans in the river. The bacterium covers bottom sediments, and as a result, the exchange of oxygen between the open water and sediments decreases. Former reports have revealed declined densities of fish in key spawning and nursery areas and benthic composition indicating organic load in the recipient. Studies that have been conducted in the area indicate that good ecological conditions will not be achieved at present. In 2013, Borregaard installed an anaerobic treatment plant to reduce discharges of readily available organic material to the River Glomma, and in June 2013 the plant was fully operative. Borregaard was imposed by the Norwegian Environment Agency to design a monitoring programme for the River Glomma. Based on the discharges and the installation of a new treatment plant. NIVA designed an operational monitoring programme according to the Water Framework Directive.