A community-wide outbreak of Legionnaire's disease occurred in Warstein, Germany, in August 2013. The epidemic strain, Legionella pneumophila Serogruppe 1, was isolated from an industrial wastewater stream entering the municipal wastewater treatment plant (WWTP) in Wartein, the WWTP itself, the river Wäster and air/water samples from an industrial cooling system 3 km downstream of the WWTP. The present study investigated the effect of physical–chemical disinfection methods on the reduction of the concentration of Legionella in the biological treatment and in the treated effluent entering the river Wäster. Additionally, to gain insight into the factors that promote the growth of Legionella in biological systems, growth experiments were made with different substrates and temperatures. The dosage rates of silver micro-particles, hydrogen peroxide, chlorine dioxide and ozone and pH stress to the activated sludge were not able to decrease the number of culturable Legionella spp. in the effluent. Nevertheless, the UV treatment of secondary treated effluent reduced Legionella spp. on average by 1.6–3.4 log units. Laboratory-scale experiments and full-scale measurements suggested that the aerobic treatment of warm wastewater (30–35 °C) rich in organic nitrogen (protein) is a possible source of Legionella infection.
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Research Article|
June 02 2016
Strategies for the reduction of Legionella in biological treatment systems
R. Nogueira;
1Leibniz University Hannover, Institute for Sanitary Engineering and Waste Management, Welfengarten 1, Hannover 30167, Germany
E-mail: nogueira@isah.uni-hannover.de
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M. Exner;
M. Exner
3University of Bonn, Institute for Hygiene and Public Health, Bonn, Germany
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W. Verstraete;
W. Verstraete
4Ghent University, LabMET, Ghent, Belgium
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K.-H. Rosenwinkel
K.-H. Rosenwinkel
1Leibniz University Hannover, Institute for Sanitary Engineering and Waste Management, Welfengarten 1, Hannover 30167, Germany
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Water Sci Technol (2016) 74 (4): 816–823.
Article history
Received:
February 16 2016
Accepted:
May 18 2016
Citation
R. Nogueira, K.-U. Utecht, M. Exner, W. Verstraete, K.-H. Rosenwinkel; Strategies for the reduction of Legionella in biological treatment systems. Water Sci Technol 17 August 2016; 74 (4): 816–823. doi: https://doi.org/10.2166/wst.2016.258
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