ENVIRONMENTAL IMPACTS OF COMPLEXING AGENTS IN THE PULP AND PAPER-INDUSTRY

The pulp and paper industry uses complexing agents (principally EDTA a nd DTPA) to remove heavy metals from the production processes of chemi cal and mechanical pulps. The potential impact of these compounds when discharged to receiving water stems partly from their nitrogen conten ts and their assumed stability in aquatic systems. The paper describes the occurrence, migration and accumulation in receiving waters of com plexing agents originating from pulp and paper mill effluents. Degrada bility and the effect of metal ion on complexing agent stability are c ompared using results from several different studies. The distribution of complexing agents in different types of recipient at different tim es of the year is studied with the help of some examples. The suitabil ity and reliability of analytical methods for use with complexing agen ts are evaluated for different types of sample. The indirect effect of complexing agents in receiving waters is possibly to promote algal gr owth (eutrophication) through the liberation of nitrogen resulting fro m their degradation. The role played in eutrophication by nitrogen ori ginating from complexing agents is assessed in the light of the latest studies.