The chemical modification of polymer plastic wastes into useful products, such as polyelectrolytes, could be a step toward their management. For these products to be obtained, the synthesis of amino derivatives of phenol-formaldehyde resin (NS-novolak) production waste by means of known methods was performed. Products that contained different contents of amino groups in the polymer chains and that were soluble in dilute KOH and NaOH solutions were obtained. The flocculation properties of these products were tested. Studies were conducted of mine water from the Kleofas coal mine and for water from the Czesto-chowa metallurgical plant blast-furnace circulation system. The amino derivatives of the phenol-formaldehyde resin waste were found to have good flocculation properties. The application of these products caused a decrease in the turbidity and concentration of the dissolved contamination and improved the quality parameters of the purified sewage. These polyelectrolytes could also be used in industrial water treatment. (C) 2003 Wiley Periodicals, Inc.