Perspectives on Biofilms for the Removal of Organic Micropollutants in Wastewater

Abstract: The use of biofilms to improve the removal of organic micropollutants in waste¬water treatment plants (WWTPs) has been investigated. The work is divided into two parts. In the first part, the use of biofilms for the biological degradation of micro¬pollutants was investigated. In the second part, micropollutant removal was investigated with biofilm processes in combination with ozonation or activated carbon. The results of the first part showed that additional biological treatment in an innovative process design utilizing a moving bed biofilm reactor (MBBR) increased the degradation rate of several micropollutants. However, further process development is needed to achieve efficient removal of a wide range of micropollutants in full-scale applications at WWTPs. The results of the second part showed that micropollutants were primarily removed by ozonation when combined with post-treatment in an MBBR. A group of N-oxide transformation products was formed during ozonation and remained stable throughout the MBBR post-treatment. Furthermore, when adding powered activated carbon (PAC) in a nitrifying MBBR, the micropollutants were removed by adsorption onto the PAC, and the biological nitrification was uninhibited by the addition of PAC. Finally, adsorption profiles of micropollutants in a granular activated carbon (GAC) filter were obtained and the biofilm that developed in the filter was able to degrade certain micropollutants such as naproxen, sulfamethoxazole, and diclofenac.