Virus elimination in wastewater treatment systems - determining rates and developing mathematical models
Zusammenfassung der Projektergebnisse
In this study a mathematical model describing virus elimination in biological systems - virus tool - was developed and integrated in the activated sludge model No. 3 (ASM3) on the basis of a mass balance approach and several batch tests. The mass balance was done within a municipal wastewater treatment plant and describes the fate of somatic coliphages in the WWTP in summer and winter season 2011. In the winter season, the concentration of coliphages entering the WWTP was about one log lower than in summer. The mass balance in winter revealed a virus inactivation of 85.12 ± 13.97 %. In summer, virus inactivation was significantly higher (95.25 ± 3.69 %, p-value < 0.05), most likely due to additional virus removal in the secondary clarifier by insolation. Thus, a removal of coliphages of about 2.78 log was obtained in summer compared to 1.95 log in winter. Rainfall events did not statistically correlate with the concentration of coliphages entering the WWTP in summer. Comparing the results for somatic coliphages with measurements of adenoviruses (performed by Dr. Selinka) showed that the behavior in the plant is comparable. This is another argument for somatic coliphages to be considered as good indicators for human pathogenic viruses. The batch tests mainly showed that the main process of virus removal in the WWTP is adsorption and that inactivation is a very slow process. Between DS-concentrations of 2-5 g/L and also high COD concentrations have no influence onto the adsorption of somatic coliphages in activated sludge. These results were used for the development of the virus-tool of ASM3. The virus tool contemplates 6 kinetic processes describing the adsorption and desorption of viruses to activated sludge flocs as well as the inactivation and reactivation of free and adsorbed viruses. The extended model was used to simulate the fate of viruses both in batch tests as well as in the biological treatment of a full-scale WWTP. Currently, the virus tool provides the three crucial factors that influence the elimination of viruses. These are the concentration of viruses, the hydraulic retention time and the sludge age in the activated sludge tank. The extended model should be a useful tool to estimate the number of viruses entering surface water after passing through the wastewater treatment plant. Further investigations of the influence of the temperature and the contribution of free and adsorbed viruses on the elimination kinetics need to be done to optimize the model. And with the aim of avoiding deterioration in water quality, the vulnerability of WWTPs to extreme climate events needs to be assessed more ac-curately to ensure better protection of the water bodies receiving wastewater effluents.
Projektbezogene Publikationen (Auswahl)
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(2011): Virus elimination in the munici-pal wastewater treatment plant of Herrenhausen in Hannover, Jahrestagung der Vereinigung für Allgemeine und Angewandte Mikrobiologie (VAAM) 03.-06.04.2011, Karlsruhe, Biospektrum
Ulbricht, K., Wolter, S. und Rosenwinkel, K.-H.
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(2012): Virus adsorption and elimination in the activated sludge of the municipal wastewater treatment plant of Hannover-Herrenhausen”, Jahrestagung der Vereinigung für Allgemeine und Angewandte Mikrobiologie (VAAM) 18.-21.3.2012, Tübingen, Biospektrum
Ulbricht, K., Wolter, S. und Rosenwinkel, K.-H.
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(2013): „Virenelimination in Kläranlagen - Bilanzierung und Modellentwicklung“, 46. Essener Tagung 13.-15.3.2013, GWA 232, Aachen
Ulbricht, K., Haun, E., Rosenwinkel, K.H. und Nogueira, R.
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(2014): A mass balance approach to the fate of viruses in a municipal wastewater treatment plant during summer and winter seasons, Water Science & Technology, 69.2, pp. 364-370
Ulbricht, K., Selinka, H.-C., Wolter, S., Rosenwinkel, K.-H., Nogueira, R.
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(2014): „Bilanzierung der Virenelimination in kommunalen Kläranlagen“, Wiener Mitteilungen (2014) Band 230, S. 185-196, Wien
Schneider, K., Nogueira, R., Rosenwinkel, K.-H.
