Integration der Spurenstoffentfernung in Technologieansätze der 4. Reinigungsstufe bei Klärwerken

The research project IST4R aimed at investigating different process combinations of activated carbon adsorption and ozonation with tertiary filtration for the removal of organic micro-pollutants (OMP) from wastewater treatment plant effluents. Its main focus was the integration of OMP elimination into treatment options for phosphorus removal for future implementation in Berlin. The investigations were carried out both in laboratory and pilot-scale. The results demonstrate that both activated carbon adsorption and ozonation can be well combined with flocculation and subsequent rapid filtration. All investigated process combinations are capable of significantly eliminating OMP with a concomitant removal of suspended solids and total phosphorus. Additionally, both dissolved organic carbon and chemical oxygen demand are reduced. The elimination of OMP is specific for different substances and processes. The concentration of background organic matter has a strong influence on OMP removal for both activated carbon adsorption and ozonation. The UV light absorption at a wavelength of 254 nm (UV254) is a useful surrogate parameter to control and monitor OMP removal with substance specific correlations. Process control using UV254 was successfully tested in pilot-scale. A monitoring using established human- and eco-toxicological methods was conducted for the different process combinations but no indications for toxic effects towards aquatic organisms or humans were observed. Besides operational parameters, investment and operating costs as well as environmental impacts were estimated using life-cycle assessment (LCA). Both costs and environmental impacts of advanced wastewater treatment are significantly increased compared to conventional wastewater treatment.