CASE STUDY
Micropollutant Concerns
Water Cycle & Ozone Treatment Solutions.
Micropollutants
The term micropollutant comprises synthetic substances that originate from anthropogenic activities and appear in small concentrations below several micrograms per liter in natural waters (e.g. industrial chemicals, pesticides, pharmaceuticals, hormones).
Emerging contaminants or CECs
Emerging contaminants or Contaminants of emerging concern (CECs) refers to any chemical discovered in water or in the environment that had not previously been detected, or were only present at insignificant levels. CECs can range from pharmaceuticals and personal care products to persistent organic pollutants used in many industrial processes.
CECs is the general term covering a wide class of different types of chemical compounds, including:
Disinfection by-products, Endocrine Disruptors, Industrial Chemicals, Natural Toxin Analysis, Persistent Organic Pollutants (POPs), Pesticide Analysis, Pharmaceuticals and Personal Care Products (PPCP).
These chemicals make it into lakes and rivers and have a detrimental effect on fish and other aquatic species. That have also been shown to bioaccumulate up the food web – putting even non-aquatic species at risk when they eat contaminated fish.
Micropollutants & CEC in the water cycle – A matter of positioning
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Micropollutants are detected in the environment at trace concentrations ranging from ng/L to μg/L
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Emerging Contaminants from more common ng/L – dilution effect usually occurs when they are discharged into the receiving environment
Context – Since 20 years
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Pristine WW Sipibel (hospital WW),
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Micropolis-Procédés (2012-2016) => Design / Sizing / Industrialisation
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Regard – Bordeaux Métropole (sources characterization)
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From which families of compounds?
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>110 000 registered substances in Europe…
Why micropollutants?
Emergence and democratization of new laboratory measurement techniques.
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Organic or mineral substances
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Proven negative effects for environment and human health
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> 200 to 1000 new every year
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Contamination sources – Mostly from human activity…
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> 90% of the European households and industries are connected to a WWTP
Examples of micropollutants – Huge family of organic compounds
WWTP Toxicity? Treated water from secondary clarifier
Which Toxicity?
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Bioaccumulation
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Biomagnification
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Endocrine disruptors
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Antibiotic resistance
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Cocktail effect
Micropollutant treatment in Switzerland – well engaged
Context:
Concept 2006 – Sensitive waterbodies
Responsibility with respect to surrounding countries
Regulation:
Entry into force of the law since 01/01/2016 (only country) treatment in WWTP before discharge removal of 80% of a list of 12 indicators
Main technologies selected:
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Ozone
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Activated carbon (AC)
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Combination of both ozone & AC
Today:
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10 plants with treatment in operation ozone 50% (3 plants with Ozonia generators)
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20 plants in planning
Goal:
120 to 130 WWTPs equipped by 2040 (approx. 50% of WW)
Background
K figures:
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Ozone dosage 0,3 to 0,6 g O3/ g DOC (< 10 mg/l)
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Hydraulic Retention time (HRT) 15 to 20 min
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Transfer efficiency > 95%
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Usual Generator size Ozonia M 1 to 20 kg O3/h
Quaternary treatment (Ozone followed by biofilter):
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Ozone + sand filter
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Ozone + GAC
Micropollutants treatment by ozone
Ozonia Scope
FOCUS on Delta UV – Differentiating ozone dosage control
ARA Neugut – Case study
At glance:
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150 000 PE
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15 000 to 55 000 m3 / d
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Treatment of micropollutants - Implemented 2014
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2 x Ozonia CFV05 (11 kg O3/h)
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Max. Ozone dose = 7 g/m3
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Design dose: 0,7 g O3 / g DOC
Conclusions
Key considerations for implementation:
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Assess bromate risk (Bromide > 100 microg / l) – presence of industrial WW
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Ozone followed by a biofiltration step (Ozone + BAC)
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Split the dose – global optimization and bromate mitigation
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Ensure micropollutant removal rate & dose optimization by on-line delta UV control
Ozone solution:
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Proven solution
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Robust, reliable & easy to operate
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Wide removal spectrum & Cost effective
References