GESZ project – Towards the good ecological status of Zenne River: Re-evaluating Brussels wastewater management

GESZ2The Zenne River crosses the city of Brussels and receives there the sewage treated by 2 WWTPs: the Brussels South WWTP (since 2000) and the Brussels North WWTP (since 2007). However, despite the considerable amounts of money invested in the construction and operation of both WWTPs, no detailed study yet existed on the consequences of wastewater purification for the receiving Zenne River.

The general objective of the GESZ project is the evaluation of the effects of Brussels’ wastewater management on the ecological functioning of the Zenne River, with the intention to provide expert advice on the optimization of future sewage management actions in Brussels.

GESZ1In this project, scientists from Brussels Universities with complementary expertise in the field of aquatic pollution have created an informal expert consortium for consultancy on aquatic environmental problems. Sampling campaigns were performed to investigate the impact of sewage release on the Zenne River at different time and space scales. Additionally, several models have been developed whose validation and application should allow us to explore various scenarios representing possible future wastewater management options in Brussels in order to support water management decision making.

In the GESZ project, ESA is in charge of the studies conducted on microbial processes associated with the carbon cycle (biodegradation), on the bacterial community structure and on the level of microbiological contamination evaluated by fecal indicator bacteria.


GESZ partners:

ANCH-VUB (Brion, N. and Elskens, M.), ESA-ULB (Servais, P.), WPC-ULB (Verbanck, M.), HYDR-VUB (Bauwens, W., van Griensven, A., Chen, M.)

Period of the study:

May 2009- April 2014.

Financial support:

INNOVIRIS – Brussels Institute for Research and Innovation (

Project web site:

ESA members participating to GESZ:

Servais, P., Inceoglu, O., Garcia-Armisen, T., Ouattara, K., Anzil, A.

Master thesis performed in the scope of GESZ :

Bois d’Enghien, X. 2010. Etude de l’activité et la diversité des bactéries hétérotrophes et de la qualité microbiologique en Senne.


Brion, N., Verbanck, M., Bauwens, W., Elskens, M, Chen, M. & Servais, P.  2015. Assessing the impacts of wastewater treatment implementation on the water quality of a small urban river over the past 40 years. Environmental Science and Pollution Research. DOI 10.1007/s11356-015-4493-8.

Ouattara, N.K., Garcia-Armisen, T., Anzil, A., Brion, N. & Servais, P. 2014. Impact of wastewater release on the faecal contamination of a small urban river: the Zenne River in Brussels (Belgium). Water, Air, Soil pollution. 225 (8) : 2043

Inceoglu, O., Garcia-Armisen, T., Ouattara, K., Anzil, A., Verbanck, M. Brion, N. & Servais, P. 2014. Seasonal variations and resilience of bacterial communities in a sewage polluted urban river. PlosOne. 9 (3): e92579.

Brion N., Servais P., Bauwens W. and Verbanck M. 2012. Past and present chemical and microbiological quality of the Zenne River. Impact of the Brussels’ sewage management. Bridges over Troubled Waters, Fifth Crosstalk publication, ISBN 978 90 7028 928 7. pp: 251-264

Shrestha, N.K., Leta, O.T., De Fraine, B., Garcia-Armisen, T., Ouattara, N.K., Servais, P., van Griensven, A. & Bauwens, W. 2013. Modelling Escherichia coli dynamics in the river Zenne (Belgium) using an OpenMI based integrated model. Journal of Hydroinformatics. doi:10.2166/hydro.2013.171

Ouattara, N. K., de Brauwere, A., Billen, G. & Servais, P. 2013. Modelling faecal contamination in the Scheldt drainage network. Journal of Marine Systems. 128: 77-88.

Garcia-Armisen, T., Vercammen, K, Passerat, J., Triest, D., Servais, P. & Cornelis, P. 2011. Antimicrobial resistance of heterotrophic bacteria in sewage-contaminated rivers. Water Research. 45 : 788-796.