Microbiological water quality in rivers of the Microbiological water - - PowerPoint PPT Presentation

Microbiological water quality in rivers of the Microbiological water quality in rivers of the

Scheldt Scheldt drainage network (Belgium): impact

drainage network (Belgium): impact

• f urban wastewater release
• f urban wastewater release

8th World Wide Workshop for Young Environmental Scientists WWW 8th World Wide Workshop for Young Environmental Scientists WWW-

• YES 2009

YES 2009: Urban waters: resource or risks? (2 : Urban waters: resource or risks? (2-

• 5 June 2009)

5 June 2009)

ECOLOGIE DES SYSTEMES AQUATIQUES

Nouho Koffi Ouattara Nouho Koffi Ouattara, Julien Passerat and Pierre Servais , Julien Passerat and Pierre Servais

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Vibrio cholerae Giardia Rotavirus

INTRODUCTION

PROTOZOA BACTERIA VIRUS

Polluted surface waters can contain a large variety of pathogenic micro-organisms The main origin : The faeces of human and other warm-blooded animals

Human origin Animal origin

wastewater effluents surface runoff and soil leaching

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The recent guidelines for assessing the water quality required f The recent guidelines for assessing the water quality required for different

• r different

water uses are based on their abundance water uses are based on their abundance (2006/7/CE) . .

The detection and enumeration of all Pathogens in aquatic sytems are very difficult

For routine monitoring Indicators of Faecal For routine monitoring Indicators of Faecal Contamination (IFC) are usually enumerated to evaluate Contamination (IFC) are usually enumerated to evaluate the level of microbial water contamination. the level of microbial water contamination.

The sanitary risk for man linked to the presence of these pathogens

The use of water The pathogens concentration in water Escherichia coli (E. coli) and intestinal enterococci(IE)

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• A monitoring survey to characterize the level of contamination

A monitoring survey to characterize the level of contamination

• f the main rivers of the watershed
• f the main rivers of the watershed
• Quantification of faecal bacteria sources in the rivers of the

Quantification of faecal bacteria sources in the rivers of the watershed watershed

• Laboratory experiments: study the fate of faecal indicators

Laboratory experiments: study the fate of faecal indicators after their release into rivers water after their release into rivers water

Objective Objective: Evaluate the water quality and : Evaluate the water quality and understand the dynamic of the microbiological understand the dynamic of the microbiological contaminants in the rivers of the Scheldt basin contaminants in the rivers of the Scheldt basin

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Description of Description of Scheldt Scheldt Watershed Watershed

Area : 21 863 km² Population : 11 millions of inhabitants High population density (around 500 inhabitants per km²), Intense industrial activities and intensive agriculture and animal farming Anthropogenic pressures High faecal contamination risk

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Results Results and Discussion and Discussion

Monitoring results of the level of faecal contamination in the rivers of the Scheldt basin

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A 1 2 3 4 5 6 7 Ly De Ne Dy1 Dy2 Se1 Se2 Se3 Ru Sc1 Sc2 Sc3 Log (E.coli/100ml)

The main rivers: poor microbiological water quality Maximum admissible for bathing water quality (EU, 2006) The Zenne river : most contaminated

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Brussels South WWTP Brussels North WWTP Km 0 Km 60 Km 20 Km 54 Km 50 Km 42 Km 31 Km 44

Longitudinal profile Zenne river

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Profiles comparison (1998 and 2008): E. coli abundance downstream from Brussels: 2 orders of magnitude higher ten years before The implementation of the WWTPs of Brussel South (2000) and Brussels North (2007)

3 4 5 6 7 8 10 20 30 40 50 60 km log (E. coli / 100 m L)

BXL South BXL North

3 4 5 6 7 8 10 20 30 40 50 60 km log (E. coli / 100 m L) 2008 1998

Longitudinal profile of Zenne river

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Sources of faecal contamination of the rivers (point and non Sources of faecal contamination of the rivers (point and non-

• point sources)

point sources)

Point sources (effluent releases ) Raw water Treated water removal rate ranged between 90% and 99% Despite this efficient removal, the WWTPs effluents still contain a high abundance of indicator bacteria

1 2 3 4 5 6 7 8 Brussel s-North Brussel s-South Wavre Grez Doiceau Wavre Nord Log (E.coli /100mL)

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Respective contribution of point and non Respective contribution of point and non-

• point sources

point sources

Point sources of faecal bacteria: largely predominant compared to non-point sources Non-point sources (surface runoff and soil leaching)

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Forests Cultivated areas Pastured areas

Log (Ecoli and IE/100 mL)

The level of faecal contamination dependent on the land use Streams from pastured areas more contaminated

• E. coli

IE

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Laboratory Experience : Decay rate of E.coli and Intestinal enterococci in Zenne water

IE decay rate in iver water

2 4 6 8 10 12 50 100 150 200 Time (h) Ln (IE)

• E. coli : T90 = 54h

IE : T90 = 72h (20 °C, In dark) THE FATE OF FAECAL INDICATORS IN AQUATICS SYSTEMS: The IE are more resistant than IE are more resistant than E. coli

• E. coli in rivers

in rivers water

water

E coli decay rate in river water

2 4 6 8 10 12 14 50 100 150 200 Time (h) Ln (E.coli)

Slope = first order kinetic (exponential decrease)

T90 T90

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CONCLUSION CONCLUSION

• The rivers of the Scheldt basin have a poor microbiological wate

The rivers of the Scheldt basin have a poor microbiological water r quality quality

• The Zenne river is particularly contaminated downstream from

The Zenne river is particularly contaminated downstream from Brussels Brussels

• At the scale of the basin, the point sources of faecal bacteria

At the scale of the basin, the point sources of faecal bacteria were were largely predominant largely predominant

• Batch experiments showed that decay rate of IE in rivers was low

Batch experiments showed that decay rate of IE in rivers was lower er than that of than that of E. Coli

• E. Coli
• The final objective of this work is to develop a mathematical mo

The final objective of this work is to develop a mathematical model del describing the dynamic of describing the dynamic of E. coli

• E. coli and IE in the rivers

and IE in the rivers

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Thanks for your attention