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#1 Posted : 26 July 2001 11:37:00(UTC)
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Posted By Deirdre Moore
Has anyone got any information about ozone as a substitute disinfectant for chlorine?

I received this query from a Farmer who uses chlorine on his farm and has become allergic to the substance.

If ozone is not suitable, perhaps someone could suggest another substance..

Deirdre
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#2 Posted : 26 July 2001 11:57:00(UTC)
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Posted By Ashley Williams
Sorry to ask but instead of Ozone (O3) do you mean Hydrogen Peroxide (H03) ive heard of it been used to disinfect things?

Ashley
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#3 Posted : 26 July 2001 12:01:00(UTC)
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Posted By John Webster
Yes
Ozone is used as a substitute for chlorine in disinfecting water supplies, but hydrogen peroxide is the frequently used altenative to chlorine (hypochlorite) based bleach.
John
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#4 Posted : 26 July 2001 12:49:00(UTC)
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Posted By Jay Joshi
If the details of the substrate(substance) to be treated is known, then it is easier to give information on substitutes. In general, bleaches,ozone,etc are oxidising agents that have or produce "free halogens(chlorine, bromine), or "free oxygen" that reacts with the organic material--bacteria and effectively kills them. However proper selection & dosage are vital, otherwise there can be environmental damage.

Ozone is a powerful oxidising agent, but cannot be stored or transported in vessels because it decomposes spontaneously in the presence of oxidisable impurities, humidity and solid surfaces. It is always generated IN SITU, for immediate use, and is extremely unlikely to be supplied as a commodity !!!!
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#5 Posted : 26 July 2001 13:11:00(UTC)
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Posted By Ken Taylor
Putting the availability and practicality questions aside, you would not want to be caught in an accidental release of either gas. The method and location of application and presence of persons at potential risk will be major dtermining factors. Are you still using Cl2 as a gas rather than Sodium hypochlorite and the like?
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#6 Posted : 30 July 2001 12:08:00(UTC)
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Posted By Diane Warne
I would recommend that you (or someone) find out from the farmer exactly what he's doing with the chlorine before the subject of alternatives can be discussed. Intended use is all-important for risk assessment here, as the above replies indicate.
Has the farmer actually been diagnosed by a doctor as having an allergy to chlorine? Maybe someone will correct me but I don't think there is any such thing as chlorine allergy, though there are many other nasty effects. Sounds like the whole scenario needs looking into by someone familiar with chemical hazards.
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#7 Posted : 07 August 2001 11:56:00(UTC)
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Posted By Eric Letherman
Ozone is sometimes used for water treatment in swimming pools and presumably in other situations, too. However, for the reasons discussed elsewhere in this thread ozone doesn't seem particularly practical for your client.

Oxfam use calcium hypochlorite for treating natural well water in developing countries, or areas where the normal water supply has been destroyed or otherwise disturbed to ensure potable water.

As already advised, the reasons for using chlorine need to be established before any alternatives can be considered.

I hope this is of interest.
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#8 Posted : 07 August 2001 16:56:00(UTC)
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Posted By Alex Shannon
I think that Diane is on the right track here – is this farmer using his PPE, although people can develop allergies to almost anything. Without knowing the case I would initially suspect an occupational dermatitis, ask questions such as:

When did you first notice you were developing the condition, and ask for continued case history?
Does this condition clear up during periods of non-usage of substance e.g. holidays?
What makes it better?
Are any other substance in use that could cause such a reaction (don’t rule out his PPE/gloves if they are being used?

As for using Cl why not Jayes fluid, much easy to handle and no need to worry about the Cl mixing with other substances that could cause explosion.

This site may be use to you aswell

http://www.maff.gov.uk/a...e/disinfection/index.htm

Hope this is of help & regards

Alex Shannon

Occupational Health Advisor, MIOSH,
and living in the middle of a FMD area (lots of chemicals about)


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#9 Posted : 08 August 2001 12:50:00(UTC)
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Posted By Jim Walker
Deirdre,

I've been following this thread with some concern.

With the notable exception of Diane's response can I suggest you ignore most of the other's.
I'm afraid many appear to have a very shaky knowledge of chemistry, disinfectant modes and COSHH requirements.

It is virtually impossible to give you a reasonable answer without knowing more detail.
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#10 Posted : 09 August 2001 11:51:00(UTC)
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Posted By Alex Shannon
Jim,

I would say that in most cases discussed in this forum/chat area it would be very hard to give a complete answer, as none of us except those asking the question have a complete knowledge of the case. So to gain some of this knowledge you must ask for details.

This, to me, is a discussion forum to share knowledge, experience and exchange ideas, to this instead of finding problems with 'very shaky knowledge of chemistry' etc, why not correct and give us all the benefit of your knowledge, so that we may all learn.

Best regards
Alex
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#11 Posted : 09 August 2001 17:00:00(UTC)
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Posted By John Webster
Yes, thanks Harry and Alex.

I, too, found the tone of Jim's response unhelpful. As a qualified chemist and chemical engineer from a farming family, formerly in water treatment and now working in healthcare in a predominantly agricultural community, I feel I am entitled to reply.

As with so many of these questions, the technical knowledge of the questioner (with all due respect to Deirdre) is often limited - which may well be why the question is being asked in the first place. It is therefore necessary to try and interpret the question rather than just taking everything literally.

12-15% Sodium Hypochlorite solution (NaHOCl) is in common use on farms, where it is supplied in, typically, 25litre drums under trade names such as "Chloros". Its main use is in washing down and cleaning out dairy areas and equipment when it is used diluted with hot water. It is an effective sterilant and, due to its causticity, suitable for cleaning where there is a coating of fats. Given the average person's chemical knowledge and (mis)-useage of the name chlorine to describe any substance giving off a bleachy smell, and given that it is highly improbable that a farmer would use "chlorine" for anything, it is reasonable to assume that the original question almost certainly related to sodium hypochlorite solution.

There was inevitably a response from those, perhaps unaquainted with farming, who naturally did take the use of the word "chlorine" literally. After all, there are plenty of undertakings where liquid or gaseous chlorine IS used, and a nasty substance it is indeed.

Two of those undertakings are swimming pools and water supply, where ozone (as Jay points out, generated in-situ) is now often used in place of chlorine. Again, there is no likely way a farm would use ozone, and so it is much more likely that the substitution issue has been confused and, as Ashley realised, the wrong name used in place of another "oxygen rich" sterilant - Hydrogen Peroxide (H2O2).

Hydrogen Peroxide is a Permitted Disinfection and Cleaning Product for use in livestock buildings under Council Proposal 8697/98 to EC reg. 2092/91: Annexe II E. I believe it is usually supplied as a 20vol 6% solution and in 25 litre drums.

The farmer should, of course, consult with his usual agri-chemical supplier who will be best placed to advise on correct application and use, and on the most appropriate PPE.

Assuming the application is one for which sodium hypochlorite may be substituted with hydrogen peroxide, there are a number of advantages. Hydrogen Peroxide is less damaging to the environment than Sodium Hypochlorite, breaking down to water and oxygen, unlike the latter which forms dangerous chloramines and other chlorinated organic compounds. It is also less irritating to the skin, mucous membranes, eyes and respiratory tract.

There could be a PPE issue here, as has been noted, given the irritant properties of sodium hypochlorite solution. It could also be that the solution is currently being used too strong, again leading to excessive exposure.

Sorry to ramble on, but I hope this gives a full answer to a vague question. If my assumptions are wide of the mark, I apologise. But then, having qualified my response, I would not expect anybody to use information not relevent to their situation.

John
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#12 Posted : 10 August 2001 09:42:00(UTC)
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Posted By Alex Shannon
John,

An excellent response addressing both subjects discussed so far.

Thank you for your time and effort, I leant something!

Regards

Alex
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#13 Posted : 10 August 2001 13:44:00(UTC)
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Posted By Ken Taylor
My rhetorical question 'Are you still using Cl2 as a gas rather than Sodium hypochlorite and the like?' was intended as a subtle way of suggesting that the questioner might be using a colloquial term for a liquid disinfectant. However, the offered Ozone alternative is also a gas added to water for disinfection and might, therefore, have also been an exact consideration. The thread seems to have gone in a strange direction on this question.
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#14 Posted : 10 August 2001 19:40:00(UTC)
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Posted By Jim Walker
Sorry if I upset anyone.

The point I was trying to emphasis was Deirdre was in need of involving a specialist to examine detail and advise.
Remember the definition of a competent person is someone who recognises their limitations.

Johns elegant answer indicated how you cannot rely on the descriptions given by the less well informed. Ken appears to be saying the same.

Although it was not intentional, it looks as though I provoked John into providing a good answer that should set Deirdre on her way.

I accept I maybe should have taken the time to construct a more positive answer, please accept my apologies.
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#15 Posted : 17 August 2001 11:51:00(UTC)
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Posted By Ashley Williams
I Realise this is in a pool environment and not a farm but it mentioned one of the alternatives we previously mentioned.

Council swimming pool chlorine incident
More than 40 persons, many of whom are children, have been treated in hospital for the effects of inhaling chlorine gas at a leisure centre swimming pool in Coatbridge. Dozens more were examined and treated at a hastily created emergency centre in a nearby primary school. Six persons in the neighbouring Buchanan Resource Centre, were also affected and taken to hospital.
Sodium hypochlorite
The major incident occurred shortly after opening time at the Time Capsule in the North Lanarkshire town. Casualties, who in the main were suffering breathing difficulties, were dispersed to several local hospitals.
Investigation will soon reveal the causation of the incident which will be of great interest to other authorities operating such facilities.
Chief Inspector David Stephen of Strathclyde Police reported: "Shortly after 9am a chemical cleaning agent was added to the pool, which caused an almost instantaneous reaction. The incident happened shortly after a lorry driver delivered a quantity of sodium hypochlorite to the pool."
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#16 Posted : 17 August 2001 14:40:00(UTC)
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Posted By John Webster
Without wishing to pre-empt the HSE enquiry into this serious case now underway, I understand that the problem may have been due to inadvertant mixing of sodium hypochlorite with hydrochloric acid. (the delivery may have been made into the wrong tank - shades of Camelford? I did hear a quote from some official on the radio that if this were the case it would be the responsibility of the delivery contractor!!!!).

Anyway, this is often the cause of this type of chlorine gas release. Effectively (chemistry lesson coming) Sodium Hypochlorite solution is the result of dissolving chlorine gas in caustic soda (sodium hydroxide). Adding an acid neutralises the caustic soda and the chlorine gas is liberated.

Many people don't realise how easily this can happen in the home by mixing bleach (sodium hypochlorite) with acid limescale remover (hydrochloric acid). Fortunately the quantities involved are much less than at a leasure centre.

Lets hope the victims all make a full recovery, and that appropriate lessons are learned.

John
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#17 Posted : 20 August 2001 19:55:00(UTC)
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Posted By Ken Taylor
I am aware of 2 cases in schools where a relief caretaker added the chemical to the wrong day-tank and started a chlorine release. However, I have also come across one in which the Ozonators continued to generate after pool circulation stopped and affected an operative within the plant room. Both chemicals have very real hazards and effective controls are called for as part of the risk asessment process. In a swimming pool we recently had built, we were able to provide separate day-tank lean-to buildings for the acid and alkali. Other measures can include non-compatible couplings, interlocks between dosing and circulation and clear colour-coded signage. You cannot assume that the pool designer will get it right. It's always worth checking. On one occasion we found that an interlock depended upon a flow switch which remained in the open position due to the head of water and poor plant room design!
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