Water and Wastewater.com Help Forums

tonyzhang YaBB Newbies Offline I love Water and Wastewater.com Posts: 2 Company or Organization: WTP	Non-ionic surfactant Dec 21^st, 2011, 2:55am Hi all, I am a newbie here. I would like to know if you ever come cross non-ionic surfactant in the wastewater stream? what will be the potential effect to the biological system and the RO membrane? Thanks.
Back to top	IP Logged

DS

God Member

Offline

sapere aude

Posts: 1582

Company or Organization: Indept. Freelance Consultant

Re: Non-ionic surfactant
Reply #1 - Dec 21^st, 2011, 4:40am

Hi Tony,

difficult question because there are many, many types of non-ionic surfactants, and in each type you have even more different molecules...

some of them should be biodegradable in a reasonable time lapse, whereas others are much slower biodegradable. Some of these surfactants may stimulate some foam forming filamentous bacteria (like Nocardia, Sorry Mycolata these days, the Nostocoida limicola morphotypes, etc..) which may (or may not...) have an effect on bio-foaming sooner or later...

these products (slowly to non biodegradable) also will build-up at the concentrate side of the RO-membrane, and also may cause bacteria to grow (biofilm) on the membrane... It all depends on what the non-ionic really is, and if it will be biodegraded fast and far enough by the biota.

BTW, which method did you use to determine non-ionic surf? I believe (not sure) the analytical methods suffer from several problems, so the determination may be at least questionable...

Back to top

www.AquaICS.be

IP Logged

David S.

Senior Member

Offline

I have nothing
clever to say here.

Posts: 373

Gender: male

Company or Organization: Environmental Express

Re: Non-ionic surfactant
Reply #2 - Dec 21^st, 2011, 8:50am

Nonionic surfactants as CTAS (SM5540D) is a very good method as far as determining the amounts of surfactant present. The biggest thing to remember is that you must carry through the sublation stage in order to remove nonsurfactants that would otherwise react with the cobaltothiocyanate. Ionic surfactants are removed with the ion exchange resin. So it ends up being a very selective test. That being said, it is a tedious and time consuming process that is easy to screw up with. The sublation glassware is also expensive and not for much use elsewhere. Not to mention all the different solvents you have to use; ethyl acetate, methanol, and methylene chloride. So unless you plan on running it regularly, I would recommend finding yourself a good lab to do it for you.

Back to top

Working hard to bring reason to the field of regulation.

IP Logged

DrHenry

God Member

Offline

Ride, boldly ride,
The shade replied...

Posts: 788
Raleigh, NC

Company or Organization: CESTAB (see bio)

Re: Non-ionic surfactant
Reply #3 - Dec 22^nd, 2011, 2:15pm

David and DS covered it well. My addition would be that at typical level, nonionics can easily be removed in a well run biological system. The horror stories are where they enter poor biological systems, then they can cause trouble. They can increase or decrease oil and grease levels depending on type and level and what O&G is present. So with RO, if done after biological, it should not matter. If bad or no biological, there may be problems.

Also, the CTAS test does not tell you what kind of nonionic is present. That requires LCMS analysis and there are few labs that can do that.

Back to top

IP Logged

The sludge judge

God Member

Offline

Posts: 649
Wisconsin
Gender: male

Company or Organization: private

Re: Non-ionic surfactant
Reply #4 - Dec 22^nd, 2011, 2:48pm

Not the most scientific way, but having a DAF and adjusting the chemistry gives me a good indication of when cationic surfactants are present. (Need to turn the cationic coagulant wayyy down- sometimes just an anionic polymer works then.). If I get hit with an anionic one, the dose needed in the jar test will be usually 2-3 times more of the cationic coagulant.

For what it's worth......

best regards,

Ryan

Back to top

IP Logged