More stringent effluent criteria will be required in the near future for the so-called priority substances listed in the Annex of the European Water Framework Directive (WFD) 2000/60/EC. This includes heavy metals, volatile and semi-volatile organic substances, pesticides and polychlorinated biphenyls. The Fraunhofer Institute suggested FHI values for these substances in water. National Dutch legislation, the Vierde Nota WaterHuishouding (NWH) introduced in 1998 ‘maximum tolerable risk concentrations’ (MTR). These include requirements for nutrients: Ptot<0.15 mg/l and Ntot<2.2 mg/l. The MTR values are being used until the FHI values become effective. Investigation into possible effluent polishing techniques is required in order to reach these objectives. During pilot research with tertiary denitrifying multi-media and biological activated carbon filtration at the WWTP Utrecht in the Netherlands, simultaneous nutrient removal to MTR quality was observed. Furthermore, simultaneous removal of heavy metals, 17β-estradiol, bisphenol A and nonylphenols to extreme low concentrations by denitrifying activated carbon filtrated is achieved.

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