Removing surfactant from waste water

A. If you have reduced drag-out to the minimum, and you dispose of batch dumps to a different waste stream, and you use biodegradable chemicals, then how about a biological system such as a rotating biological contactor?

Do you have a local pretreatment limit on surfactants or foaming? Do you discharge to a stream or lake?

<== 'Standard Methods ...', (American Public Health Association, Washington DC, USA) has two methods for determination of surfactants;

#512B, Anionic Surfactants as MBAS ( methylene blue [affil links] active substances)

#512C, Nonionic Surfactants as CTAS, (cobalt thiocyanate active substances)

Are you testing for surfactants now? Perhaps as part of a comprehensive plan to reduce surfactants or foaming, you can chart the results of one or both of these tests.

A. I don't know -- I did not mean to imply that I have used the method. In reading through the procedure, we have a sublation step (bubbling through an ethyl acetate layer), anion and cation exchange, and partition of CTAS into methylene chloride before measurement.

The method does not list interferences by chelates, but it would be worth a spiked sample to find out for sure. Not too many plating shops in these parts have much chelates in the process anymore.

A. There are several methods to minimize surfactant levels in waste water and much depends on surfactant levels, ionic types, builders, time restraints, acceptable levels, and how much you are willing to spend.

Anionic surfactants are often amenable to treatment with alum and regulation of pH followed by polymer flocculent. I like the bentonite clay powder blends that can treat a wide variety of cleaning wastewaters. They are quick, simple, and some can break emulsions stabilized by nonionic surfactants as well as remove the low parts per million. If needed you can polish with granular organophilic clay and/or activated charcoal filtration.

Of course, it saves time if you know the surfactant level that you are up against and can test those levels as your wastewater varies from day to day or hour to hour.

James

A. Organo clay can be used to remove surfactants from water source. Other method is to use polyelectrolyte flocculants. Cationic quarternaries are efficient but less cost effective.

A. If you are interested in getting the surfactants out and have already segregated the concentrated stuff (like cleaner dumps) why not go all the way and recycle the water. Then it makes sense to run the stream through a carbon bed. Couple that with ion-exchange and you have deionized water for reuse in any rinse in your shop. It's what we do, and it works great.

A. I was scanning quickly through the different methods proposed to treat anionic or non ionic surfactant in plating (surface finishing) effluents. Which can summarized as follows:

1- H2O2 (hydrogen peroxide) which will probably do the job specially at higher PH combined with UV light

2- Organophillic clays

3- Adsorbers such as activated carbons & bentonites

But no one seems aware that Ozone which can be produced from ambient air or oxygen will break down all the organics surfactants, brighteners ,...etc to CO2 & H2O & N2 when applied under the appropriate conditions.

Basically the organics are burnt in an aqueous environment.

Ozone used to be expensive to produce , but now with the advancements in new materials and electronic Ozone can be generated affordably. The capitalisation is high but on the long run it will compete with other solutions.

Ozone will precipitate most of heavy metals so the water can be really recycled without the use of R.O or distillation.

A. Electroflotation is effective in removal of surfactants from plating waste and rinse waters. Technology is based on water electrolysis. The resulted hydrogen and oxygen bubbles foam surfactant which is collected from the top of solution.

A. The anionic surfactants are neutralized using cationic surfactants and vice versa.

By spectrophotometric via, you can determine the level of surfactant and calculate the quantity required to neutralize the concerned surfactant.

The complex compound resulting from the reaction is biodegradable.

This method is very fast and cheap.

Hi Raj. I think some readers may be willing to help you a bit, but I don't think it's going to work to ask a stranger to identify a potential project for you. Do you have any particular industrial effluent in mind? Where will you get samples? Any idea in what way you would hope that a surfactant will solve or assist with the pollution problem? Sorry, but I'm not clear about what you have in mind. Thanks.

Regards,

A. Hi Sophie. Electroplating is a broad field involving the deposition of about 22 metals, plus alloys, while also requiring and involving efficient cleaning and oxide removal ... making it very hard to delimit. Further, it often involves proprietary formulas -- such that few if any users are fully aware of what organic materials may be in the wastewater that they are trying to treat.

If it is possible to make contact with a local plating shop, they might appreciate your help, and both you and they will probably have access to resources that the other doesn't have.

If that won't work and you must make your own wastewater, this page discusses 'surfactants', which are one of many classes of organics employed in plating solutions, and which should be easy to obtain for your experiments. Good luck.

Regards,