ABSTRACT
With increasingly stringent wastewater discharge regulations in the United States, particularly for the organic chemicals industry, and a new emphasis on control of effluent toxicity, many industries are faced with upgrading and retrofitting activated sludge plants. These upgrades may involve increased removals of specific organics (i.e., phenol), improved winter performance, and reduced effluent aquatic toxicity. This paper presents methods available to upgrade such systems, rationale for process selection, and several case histories demonstrating these methods.
