Dear Islam,

I think people are not so willing to use the ozone water because its very expensive when compared to chlorine as disinfectant.

Sara;

 Although the production of chemical byproducts are fewer with ozone than chlorine, there are some disadvantages to ozone disinfection. Ozone has been shown to produce small amounts of bromate which is a suspected carcinogen. More importantly, like ultraviolet water purification, ozone disinfection provides no residuals in the distribution system to suppress regrowth. Thus, if any harmful microorganisms survive the initial O3 disinfection, there is a risk that there might be regrowth in post disinfected water supplies. To guarantee public safety Ozone disinfection should be augmented with some level of disinfectants, like chloramines, that can provide a persistent residual.  Generation of ozone using an air feed can also lead to the formation of NOx and NO2 / NO3 residuals in the disinfected waters. (This can be avoided if pure oxygen is used as the ozone generator feed gas.)

One of the best arguments for utilizing ozone to disinfect water is that the process creates oxygen as an unreacted residue. Ozone oxidation also occurs during a lightning storm and when O2 reacts with ultraviolet sunlight in the atmosphere. By using O3 to purify water, we are basically imitating and harnessing a natural process. With a redox potential of ~2.07 ozone can effectively oxidize and kill harmful bacteria, viruses and other pathogens thereby effectively sterilizing the media; while avoiding, for the most part, the creation of toxic disinfection by-products. 

Regards

Dear Steve,

Thank you very much for your comment and good information about ozone as disinfectant.

Dear Sara Sayed and Steve A. Carr

Thank you so much for the reply. 

I got to know a new thing that ozone can produce a small amount of Bromate, a possible carcinogen. But, the producer is saying it is completely safe. However, from my understanding, I could learn that it could be a better disinfectant than chlorine if it can be available within our budget.  

One of its drawbacks compared to chlorine gas that it remains in the water network for a shorter time. Chlorine gas lasts for 24 hours which is not the case for ozone. Best regards. 

dear

i agree with Dr. Nabeel Hameed Al-Saati opinion

regards

I am working with ozone treatment of water and I have assisted several companies that have been or still are developing disinfection solutions based on ozone in water.

Small scale ozone generators and swing absorber type oxygen generators have developed a lot in the last decade making it much more economic and energy effective to produce ozone in small scale. Thus the cost of ozone doesn't make ozone disinfection less competitive than chlorine water and organic disinfectants.

 Bromate is cancerogenic only if it is ingested. For this reason one should be concerned with it there ozone is used for food and water disinfection, but not then it is used for equipment or surface disinfection.

I find the problems in using ozone for disinfection is with that it is a gas which irritates the nose at low concentrations. In designing safe disinfection systems it is a challenge that ozone react very fast with many organic substances causing that it might be lost too fast to give enough disinfection if there occasionally is a contamination of the disinfected object with certain organic matters. 

All the methods of water disinfection have advantages and disadv., and the use of ozone gas is one of those methods. The main advantage of ozone is that the process of disinfection requires less time, and not to produce halogenated organic materials( only in the case of the presence of bromide ions), while the main disadvantage is that the gas is unstable so it should be prepared in the site. The chlorine can not be dispensed with, because ozone can not prevent the growth and reproduction of bacteria and does not keep the water disinfected for a long time compared with the use of chlorine.

In addition to the issues/constrains explained above, others should also be taken into account when you make the decision of using ozone. 1. The target water matrix (drinking water? wastewater? wastewater reuse?) and 2. the respective local (national) regulations. For example, if the local regulation does not set any limit for disinfection by-products (DBPs) in drinking water, the cheaper disinfectant is used (typically chlorine), but if only chlorination by-producs (typically trihalomethanes (THMs)) are regulated, this restriction will drive the choice of the disinfection process on alternative options (among which ozone...which should be coupled to a secondary disinfectant which can leave a residual in the distribution network). In Italy, 3 DBPs (namely, THMs, bromate and chlorites) are regulated in drinking water, which make the choice of the most suitable disinfectant strongly related to water characteristics (in particular DBPs precursors).

A different discussion is related to wastewater disinfection (and possible reuse). As effluent disposal into the environment is of concern, typically DBPs are not regulated, so also in this case the choice is only driven by the cost. But as wastewater reuse is of concern, the choice is strongly affected by local regulation; again in Italy the regulation sets a limit only for THMs, so alternative disinfections processes (e.g., ozone) are feasible.

Dear Professors and Scientist

Thank you so much for the nice discussion. There are lots of new things to learn. Can you please explain me what kind of problem we may face if we use the ozonated water as hand sanitizer specially in the hospitals, clinic and nursing homes, where usually different commercial sanitizers are being used. 

Thanks and regards.

Hand disinfection by ozonated water is not easy because one has to balance the dose applied between delivering enough ozone to achieve sufficient disinfection and on the other side not having so much ozone that it irritates the noses of the doctors and nurses.

Additionally there is the issue with ozone reacting very fast with many organic substances causing that it might be lost too fast to give enough disinfection. In the clinit this might be application of a cream or gel to the hands. In the surgery room this is less problematic as one can control that the staff scrub and washed with before disinfection.

Disinfection of gloves are much easier than the skin of hands due to the smooth surface.

Patent APPARATUS, METHOD AND SOFTWARE PRODUCT FOR HAND SANITISATION...

I take an opportunity to appreciate the answers given by Dr Henrik., Dr.Luigi, Dr. Isam and Dr. Steve. They are quite satisfactory

As stated by Dr Sheth

As stated by Dr Sheth

As stated by Dr Sheth

I am looking at the option of using Ozone CIP in our process. I would request inputs from the group, on consideriing this system for equipment disinfectation. any impact of ozone in nutritional product/equipment.

Our intention is to use Ozonated water as a disinfectation at the end of Chemical CIP.

1. Are there any recommended concentration & contact time for getting better microbial load (Log) reductions.

2. We do use Chlorinated water at ~1.5mg/lt. What is the probability of Bromite generation when Ozone added to this?

Pl. let me know If you feel any other information deemed important

Durga Prasada Rao Kara For CIP, have you considered electrolysed water neutral PH ( HOCL) ?

Mr. Satish Jain, I have not considered this because of 1. Free chlorine can cause corrosion. 2. Ozone is faster than HOCL 3. No by product