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Ozone Technology in Drinking Water Applications

Curio can provide tailored ozone systems.

Why Curio?

We offer not only technology, but a complete ozone solution adapted to client specific needs from audit to development of the tailored solution.


We have access to our own ozone laboratory that facilitate:

  • R&D AND Application Research

  • Onsite Pilot Planting

Water Flowing Out Pipe

Systems can be sized to your process requirements, and for any market that requires the use of Ozone.






Fixed or mobile solution



Curio’s Engineering Team will support you at every stage of the process

  • Tailor made solutions

  • Plug & Play

  • Fully-assembled and tested

  • Modular systems

  • Fixed and containerized systems

  • Remote control


Principles of Ozone

  • 50% stronger than chlorine

  • Converts back to harmless oxygen

  • Greater water solubility than oxygen

  • Generated and used directly onsite

  • Most powerful commercial oxidizing agent

  • Tri-atomic form of oxygen


Design of Contact Chambers and Ozone Diffusion Systems

In a conventional fine bubble column reactor, mainly used because it is operated without the further addition of energy in addition to that of initial carrier gas compression, 3 cases can be considered:


When ozone reacts very fast with compounds to be oxidized (oxidation first order rate constant about 104 s-1), the reactions take place only at the bubble surface and no ozone is transferred into the bulk of the liquid phase. In this case, it is necessary to enlarge the specific exchange surface of the bubbles to transfer ozone from the bubbles into the liquid film around the bubbles as fast as possible. The contact time of the liquid bulk inside the contactor is not the main concern.



When the velocity of the reaction is fast (oxidation first order rate constant about 102 s-1), the oxidation rate is often limited by the ozone transfer velocity from the gas phase to the liquid phase. In this case, for a given specific exchange surface, it is necessary to increase the driving force (ozone concentration in the gas phase –dissolved ozone in the liquid phase).



When the velocity of the reaction is low (oxidation first order rate constant about 1 s-1 or less), dissolved ozone residual appears in the bulk of the liquid before oxidation reactions take place, and a high ozone driving force is not as essential compared with the necessity of having a homogeneous dissolved ozone concentration in the bulk of the liquid.


In general, the oxidation reactions of ozone with easily oxidizable compounds occur in a much shorter time frame than does disinfection. It means that when disinfection is concerned, the case 3 is applicable

Typical Ozone Introduction Points


Advantages of Using O3 In Pre-oxidation

Taste and odour removal

Treatment technolgies


Colour removal

Treatment technolgies

  • Colour in water may result from the presence of natural metalic ions (iron and manganese), humic/fulvic substances, colloidal particles, plankton, weeds, and industrial wastes.

  • Natural organic materials (nom) are probably one of the most common components that cause the colour in water

  • Colour is removed to make a water suitable for general and industrial applications


Drinking Water before and after Ozone

Ozone dosage: 1.0 – 3.0 g/m³

Improve coagulation

Coagulation is improved by Ozone


Ozone assists in the process of coagulation by destabilising particles ('micro-flocculation').

Oxidation of the particle surface changes the coagulation behaviour of the particles by e.g.:

  • introducing carboxyl groups

  • compression of the steric active layer

  • reduction of molecule size

  • release and oxidation of metal ions etc.

Up to 30-50% improvement of filtration efficiency

Ozone Disinfection Mechanism  


Bacterium structure

DNA Nucleic acid

Cell Wall

Ozone energy is strong enough to directly destroy the cell wall and to inactivate the organism.


Chlorine must first diffuse through the cell wall and then will inactivate the organism.


C*t parameter is used for disinfection

C: Disinfectant concentration

t: Contact time


C*t value

C*t = concentration (mg/l) x contact time (min)

Typical CT value for disinfection is 1,6 min*mg/l

e.g. 4 min x 0.4 mg/l residual ozone concentration 8 min x 0.2 mg/l residual ozone concentration

'CT' (minutes*mg/L) in the context of water treatment is defined as the product of:


  • C, for 'residual disinfectant concentration' in mg/l (determined before or at the first customer)

  • and T, for the corresponding 'disinfectant contact time' in minutes.


CT is a measure of the disinfection process reaction time.


CT is one of variables that control the effectiveness of the disinfection process.

Disinfection Perfomance Rate 


CT – Contact x Time

The lower the CT, the higher disinfection power

Comparison of CT values in mg-min/L for various oxidants to achieve 2-log (99%) inactivation of the given organism at 5°C, as noted by Hoff, USEPA, 1986 ; Rakness 2005 ; USEPA 1999


Log Reduction E-coli


Main Oxidisation 

Advantages of using O3 in Main Oxidation

Design Advises

  • Disinfection should always be after pre-treatment reducing the amount of suspended solids and followed by GAC

  • Typical ozone dosage: 1.0-3.0 g/m3 (up to 5 g/m3 for virus contamination)

  • Typical contact time: overall 10-20 minutes

  • A residual ozone concentration to be maintained in any case to reach disinfection

  • Take care on contact tank design (avoid short circuit)

Biological Purification

Removal of organic matter

  • In main ozonation some mineralization to CO2 takes place

  • Ozone 'cracks' COD and produces biodegradable fragments
  • Further reductionod COD in biological activated GAC / BAC filter following the ozonation
  • If BAC filters are used the active biofilm remains in the inner structure of the carbon particles (no continuous removal during filter backwashing)

Main advantages of using O3 over chlorine

  • Rather short retention times required

  • Very significant reduction of CL2 needed for network protection or no  CL2 needed

  • TOC reduction in combination with a biologically active filter
  • Immediate disinfection efficiency (Cryptosporidia, Giardia,...)

“We’re visionaries, big thinkers who see the world differently, dreaming up the solutions no one else can. Striving for perfection, we embrace the boldest ideas and welcome every challenge.


For us, every problem is a starting point, an opportunity to come up with an idea that might change the world.


With our passion and ambition, the possibilities are limitless.”

Brave thinking.

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