Rainwater harvesting: What are the Rainwater harvesting: What are - - PowerPoint PPT Presentation

Rainwater harvesting: What are the Rainwater harvesting: What are the potential effects of roof maintenance on potential effects of roof maintenance on runoff quality? France as an example runoff quality? France as an example

9th WWW-YES, Belo Horizonte MG, Brazil, 26-30 October 2009

Antoine Van de Voorde

LEESU (ex Cereve)

Action financée par la région Ile-de-France

WWW-YES, Rainwater harvesting, Van de Voorde

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Plan Plan

• Introduction
• Methodology
• Results / Discussion
• Conclusion

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Introduction Introduction

• Currently in France:

▫ Success of rainwater harvesting & re-use ▫ Governmental promotion harvesting & re-use (tax reduction) for soil cleaning, toilets,…

• BUT…

▫ No reflexion about rainwater quality & risks associated rainwater are « pure » ▫ Contaminations by trace metals (Robert-Sainte, 2009) &

• rganic micro pollutants (Burkhardt et al., 2007)

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Introduction (2) Introduction (2)

• Practices are source of micro pollutants

▫ Cleaning the roof for embellishment ▫ Use of biocide

• During rain possible leaching of these biocides

Necessary to evaluate level of contamination & risks

• f roof runoff re-use !

WWW-YES, Rainwater harvesting, Van de Voorde

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Methodology Methodology

• Listing roof treatment products / Survey of

professionals

▫ Determination of practices ▫ Knowledge of roof treatment undertaken

• Compositions (SDS)

▫ Isolation of biocide molecule(s) & toxicity

• Bibliography

▫ Types of contamination in countries where rainwater is drunk (developing countries, …)

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Results & Discussion: Listing / S urvey Results & Discussion: Listing / S urvey

• Fungicide is the most

popular treatment product

• Result confirmed by

survey:

Product type Number of products Utilisation Primary cleaning 3 Primary elimination of plants Fungicide 18 Destruction of fungi and incrusted lichens Waterproofing 7 Increase of resistance to water for porous material Paint 4 Embellishment / Waterproofing

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Results & Discussion: Biocide used Results & Discussion: Biocide used

• Quaternary Ammonium Compounds

(QACs):

• Toxicity:

▫ Highly toxic for aquatic environment (EC50 < 1 mg/L) ▫ Irritant and allergen to skin contact, possible asthmatic reactions

• For 100m²

roof: 400g 1000g of QACs Risks exist for users and environment by mobilisation of QACs

R3 N

+

R4 R2 R1 Cl

• N

+

CH3 C H3 CnH2n+1

Alkylbenzyldimethylammonium (n° CAS : 8001-54-5)

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Results & Discussion: Drinking water Results & Discussion: Drinking water

• Rainwater = Source of drinking water for countries

without good or enough water ressources

• Not a novel concept in Africa

▫ South Africa: Rainwater major source of drinking water during rainy season ▫ Development in rural areas

WWW-YES, Rainwater harvesting, Van de Voorde

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Results & Discussion: Drinking water (2) Results & Discussion: Drinking water (2)

• For drinking water Quality has to be good enough !
• Studies in New Zealand and India:

▫ Bacteriological factor limits the consumption of rainwater (for 30 to 90% of cases) ▫ Small proportion of chemical contamination but more difficult to eliminate

Risk by bacteriological & chemical pollution

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Conclusion Conclusion

• Rainwater harvesting contemporary issue
• Contaminations exist for countries with good source of

drinking water (a) and countries which need rainwater for drunk (b)

• Sources of pollution different
• Different approachs:

▫ (a): guide maintenance of roof and storage tank ▫ (b): increase knowledge of rainwater contamination & harvesting technics and guide population if possible health risks

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Thank Thank you you for for your your attention attention