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desinfection of biofilms


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32 replies to this topic

#1 pito

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Posted 03 March 2009 - 07:37 AM

hallo all,

I was wondering if anyone here has any experience in the field of desinfection of wastewater/biofilms.
I am mainly looking for some environment friendly methods. I know of the standard methods like UV, Ozon, chlorine etc.. and combinations, but I am wondering if anyone here has other experiences (experiences with the regular used ones is good too.) at their company, research units?


I was thinking on trying out a combination of fysical and chemical desinfection.

Another idea I had was the use of salt. I do not know if anyone here has ever had the idea to use an excessive amount of salt to kill of bacteria, fungi.
It seems easy to recuperate the salt and thus not harm the environment.
However I have not looked into the details.

I am mainly doing some general research at the moment and looking for some good articles , if you have any reference, that would be appreciated.

If you don't know it, then ask it! Better to ask and look foolish to some than not ask and stay stupid.


#2 GeorgeWolff

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Posted 03 March 2009 - 02:22 PM

I have both lab and industrial experience. None of the treatments mentioned (nor salt) is reliable to disinfect biofilms. The critical target is what is usually a polysaccharide matrix and biocides don't penetrate.

Biofilm of what microbes are you thinking?

#3 pito

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Posted 05 March 2009 - 03:12 AM

I have both lab and industrial experience. None of the treatments mentioned (nor salt) is reliable to disinfect biofilms. The critical target is what is usually a polysaccharide matrix and biocides don't penetrate.

Biofilm of what microbes are you thinking?


It is wastewater that needs to be desinfected.
However I do not have enough details yet about what kind of water, but in general we will be testing the "common" bacteria.

I'll have get some more details, we are still a bit working in "the dark".

So you do not have any good experiences with it.
Thats not good news for me.

If you don't know it, then ask it! Better to ask and look foolish to some than not ask and stay stupid.


#4 GeorgeWolff

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Posted 05 March 2009 - 04:32 AM

Industrial applications that demand high purity (purified water) usually rely on dramatic interventions when biofilms are present such as caustic (NaOH) rinses.

#5 pito

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Posted 05 March 2009 - 04:42 AM

Industrial applications that demand high purity (purified water) usually rely on dramatic interventions when biofilms are present such as caustic (NaOH) rinses.


Well I have gotten some more information.

It seems they want to make some pilotproject.
They are going to create biofilms "poluted" with Pseudomonas a

If you don't know it, then ask it! Better to ask and look foolish to some than not ask and stay stupid.


#6 pito

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Posted 05 March 2009 - 04:48 AM

Industrial applications that demand high purity (purified water) usually rely on dramatic interventions when biofilms are present such as caustic (NaOH) rinses.


Well I have gotten some more information.

It seems they want to make some pilotproject.
They are going to create biofilms "poluted" with Pseudomonas, E.coli and 2 others that they are still discussion.
(they are trying to get the most common polution , however (strangely enough) they do not seem to have a "real" case scenario , meaning : what kind of water they are going to desinfect eg. from where does the water come...)
Thy are really going to create an artificial polution.


It will be a small project on water treatment.
The techniques they want us to look at are Uv, ultrasound, chlorine, elektrolyses , peroxide and javel water.

How would you figure out what treatment works best? Just plating out the samples before and after and count cfu's ?

If you don't know it, then ask it! Better to ask and look foolish to some than not ask and stay stupid.


#7 GeorgeWolff

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Posted 05 March 2009 - 05:03 AM

Pito - I am amazed. Who are these ignorant "they" folks. It's clear they know little to nothing of microbiology but why can't they read? The literature is full of relevant reports on biofilms. some of these treatments are simply ludicrous efforts re. biofilms (UV and ultrasound) and others are well known to be useless (hypochlorite, peroxide).

To confirm (here. lack of) efficacy, test the surface material(s). Looking for free-floating (planktonic) cells is not helpful.

As I said pito, this is really stupid for an adult effort. Looks like a glorified 9th grade science fair effort.

#8 pito

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Posted 06 March 2009 - 02:56 AM

Pito - I am amazed. Who are these ignorant "they" folks. It's clear they know little to nothing of microbiology but why can't they read? The literature is full of relevant reports on biofilms. some of these treatments are simply ludicrous efforts re. biofilms (UV and ultrasound) and others are well known to be useless (hypochlorite, peroxide).

To confirm (here. lack of) efficacy, test the surface material(s). Looking for free-floating (planktonic) cells is not helpful.

As I said pito, this is really stupid for an adult effort. Looks like a glorified 9th grade science fair effort.



Yeah, well I was thinking less or more the same.

You have any good literature references ?

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#9 GeorgeWolff

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Posted 06 March 2009 - 04:25 PM

look up Costerton and center for Biofilm Engineeering at Bozeman.

#10 pito

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Posted 07 March 2009 - 09:23 AM

look up Costerton and center for Biofilm Engineeering at Bozeman.


Ok thanks.

I'll check it out.
Anyway, I am gonna look into the use of chloride desinfection and the use of UV.
But indeed as you said, against biofilms they seem to be useless. However the combination of UV and substances that give free radicals might work.
And chloride is well known as a desinfectant.

If you don't know it, then ask it! Better to ask and look foolish to some than not ask and stay stupid.


#11 GeorgeWolff

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Posted 07 March 2009 - 06:15 PM

Hypochlorite is - not chloride ion - and that is neffectively neutralized within the biofilm.

Come on pito - you're a smart person. UV for biofilm?? Give me a break.

and please (!) - it's disinfectant.

Edited by GeorgeWolff, 07 March 2009 - 06:16 PM.


#12 pito

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Posted 08 March 2009 - 03:34 AM

Hypochlorite is - not chloride ion - and that is neffectively neutralized within the biofilm.

Come on pito - you're a smart person. UV for biofilm?? Give me a break.

and please (!) - it's disinfectant.



Ah yes, indeed, hypochlorite I ment, its hard for me to adapt to the english terms etc.
And yes, disinfectant , my bad.
And yes, as you said: biofilm does neutralise the hypochlorite to a certain amount.
Thats why I was also thinking on using a biodispersant.

About the uv, you are right that it doenst work well for biofilms, however I found an article that speaks of a combination PAA and UV and they got "good" results with it.
Although I do still need to break up the biofilms to get a better result I think.
I was thinking on using a biodispersant to break up the biofilm.

However, I think you make a strong point and it is indeed a lost effort to try uv as there are to many parameters that have an effect on the uv irridation.

But its not my call, I just do what they want me to do.

If you don't know it, then ask it! Better to ask and look foolish to some than not ask and stay stupid.


#13 GeorgeWolff

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Posted 08 March 2009 - 04:20 AM

Understand - you have to do what they say.

Do you have the opportunity to pass on your technical perspective re. likely success? In any case, be real clear with success (here likely failure) criteria.

Are you try it on the construct in question or trying to develop a representative model?

#14 pito

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Posted 08 March 2009 - 05:12 AM

Understand - you have to do what they say.

Do you have the opportunity to pass on your technical perspective re. likely success? In any case, be real clear with success (here likely failure) criteria.

Are you try it on the construct in question or trying to develop a representative model?


its a small research unit at a school. They have allready done some minor attempts and now they are going to work a bit more on it. They want to invest some basic techniques. Very small sized test and not really representive to real live situations.

I am not sure if they are going to publish anything or rather keep it internally and maybe towards the future try to do some more bigger scaled research.
I think its mainly a pilot project to see whether there is any future in.

If you don't know it, then ask it! Better to ask and look foolish to some than not ask and stay stupid.


#15 GeorgeWolff

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Posted 08 March 2009 - 05:30 PM

I hear this with regret . Ignoring the existing science is always a mistake.




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