Electrocoagulation vs. Ion Exchange

A. Someone gave a paper on the electrocoagulation at either Sur-Fin or AESF Week. AESF should be able to find the most current one.

I saw it advertised on the floor of AESF week , many years ago. My thought is, if it is so good, why haven't we heard more of it in the last 15 years? It works in the lab, but will it work at your facility with your people taking care of it?

Ion exchange is an expensive option. It does have considerable value as a polishing agent, especially if you are trying to recycle some of your rinse water. Any number of vendors will literally bury you with information about ion exchange if they think that you might buy one.

The only electro-coagulation installation I saw had a final 'polish' through disposable resin (massive quantities thereof) . . . and I got the feeling that the whole system worked exactly as well whether the electro-coagulation device was plugged in or not :-)

I'm not able to see the point of the one system I saw, electrocoagulating waste before passing it through ion-exchange. My only experience may have been with a snake oil installation :-)

What I saw was a table top demo, in a beaker. It worked quite nicely on a pure new plating solution rinse equivalent.

I had real doubts on reliability on scale up.

I did not get a satisfactory answer to my questions on real world, filthy, nasty, mixed process effluent.

I was being nice, because I had never worked with it. Personally, it would take quite a bit of pilot plant work before I would put it into a customer's facility.

I think that we are saying similar things, but in different words.

Jim

A. Ted and James,

Electrocoagulation was a very popular and well-developed technology in the former USSR 10 years ago. I have studied under prof. Rogov who was an authority on the matter, published books (I own one) and papers on the topic. He also lead an organization that designed and installed e/coagulation water treatment plants. What I am not sure of, is what kind of discharge concentrations they were able to achieve at the time and how those would compare to modern-day standards of this and other developed countries.

Hope this helps,

PlaterB

There seems to be a lot of confusion regarding what Electrocoagulation is.

Electrocoagulation uses DC current and consumable iron or aluminum anodes. The iron or aluminum that dissolves is the coagulant. Due to the low currents involved, it is not usually suitable for more that a trace of cyanide, or hexavalent chromium, but some oxidation and reduction does occur. If iron anodes are used in the presence of cyanide, you will form ferrocyanide complexes that cannot be destroyed by chlorination. After the electrocoagulation step, the treatment is similar to conventional treatment by flocculation and settling. It is more similar to conventional treatment than different from it. Pretreatment of cyanide wastes by chlorination before further treatment is a better idea then electrocoagulation. After that the choice to use strictly conventional means or EC is up to you.

Ion exchange is not s substitute for treatment of metals or cyanide. It can be used along with treatment for various purposes. Ion exchange does not destroy cyanides and is not used much on cyanide wastes except for precious metal recovery. It cannot treat metals to a disposable form, but is extremely useful to concentrate metals in dilute concentration so that they can be treated in a small volume more efficiently. In this regard it is used to polish the effluent from conventional treatment or as an alternate to conventional treatment.

Water treated by ion exchange to remove metals can be neutralized and discharged, while a small concentrated regeneration volume can be batch treated. In some cases a continuous treatment system ca be replaced by IX and batch treatment.

Deionization is also used to recycle water, but usually only very dilute rinses.

Ion exchange is also used extensively for precious metals recovery, including from cyanide baths and rinses. In these cases, the resin is usually not regenerated, but burned to reclaim the precious metal. This also destroys the cyanide.

A. We are consultants and manufacture representatives for various company's technologies in the treatment of acid mine drainage. Our primary marketing area is Pa. and West Va. as well as the TVA authority. We work with various governmental agencies as well as the coal companies who are treating these waters.

We represent a manufacturer of electrocoagulators that will treat AMD and the objective is to separate the metals from the sludge that results from the water being put through the electrocoagulator. We are in the process of setting up a beta site here locally and doing a demonstration of same. Lab tests have shown where we can remove 98% of the metals and there is a market for these metals which includes gold. It is estimated (through a research project funded by the Heinz Foundation) that we have in this area of Pa. 26 tons of gold in the AMD. I fell there is tremendous opportunity in this technology. The company we represent will have in 2/2000 a unit that will handle 1,000 gpm. The problem in the past with the principle of either AC or DC electrocoagulation has been that no one really did any real work above 100 gpm, and the industry saw a lot of "unethical" people doing the black box thing as well as ripping off potential investors. We are slowly changing that image and most of those companies are out of business. There are a couple still there but we know who they are.

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Sorry, Ken, these pages are restricted to camaraderie and technical discussion. We don't go "commercial" with suggesting brands, both because the internet is too anonymous to know people's vested interests, and because the site is made possible by supporting advertisers who wouldn't be able to support a site if it steered people towards their competitors who pay nothing :-)

A. We are currently using a 2.5 GPM electrocoagulation cell with steel electrodes to process Alodine rinse water (we use Alodine as a conversion coating prior to painting aircraft). To the best of my knowledge, this is the only such application in the AF, but there is a lot of interest now being developed. The rinse water is of variable composition, usually 100-400 ppm hexavalent chrome. It usually reduces chrome to non-detect levels in 3 passes. It works for us, but we are operating on a very small scale in batch mode.

I have been using electrocoagulation technologies for several years in the treatment of AMD; heavy manufacturing (automotive); metal plating (Zn, Cd, Cr+6 / Cr+3, Cu, Au); and drinking water (As). I can appreciate what other commenters have said about the unethical "jack-legs" that seem to pervade this market sector.

The technology still has a way to go but is more than just a passing fancy.

Cal

I realize that this is an old string and may never be read again, but the head of the Chemistry Department at a University in Texas, feels that this string needs one more message. Electrocoagulation works, and it will work on low or high concentrations of mixed waste from any number of sources including tanneries, dyes, plating, emulsified oils, etc. It is based on solid, scientific principles of electrochemistry and is as predictable as the waste characterization allows. There have been few technical papers prepared but that number is increasing. As water re-use interest grows, so does interest in this technology. Ion exchange is fine for relatively clean water. Dirtier water (high TDS) can be passed through EC first, increasing the effectiveness and reducing the cost of ion exchange. Unfortunately, there have been many "black boxes" and pretenders in the technology. While anyone can make it work in the laboratory, solid engineering is required to produce an industrial strength system. Electrocoagulation is now appearing from coast to coast. Those who suffer from a bad supplier experience should not rule out the technology. That University is just now fielding a system jointly with the US Department of State, Mexico, and several universities in Mexico to demonstrate the technology along the US-Mexico border. Their interest is based on years of highly technical research and development and will hopefully result in the development and publication of more solid application data.

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Ed. note: The thread has been read thousands of times, Paul, and will be read thousands more, so thanks for the update! Unfortunately, testimonials are of little value on a largely anonymous internet where it is impossible to know the vested interests of the posters, so we don't print company or university names. Thanks again.

A. I am looking at this technology very hard. Our company has a current EPA project that is testing one of their commercial facilities. The problem in the past is fouling of the electrodes for many different reasons and this company seems to have solved them.

Regards,

A. Electrocoagulation works if the process is well developed. We are currently testing two systems at a tanning plant and at a chromium plating facility. The process is well defined and results are reliable and reproducible. We are utilizing AC current EC with pulsed current.

A. It looks like everyone has a common problem

I can't even count how much stuff I have kicking around in my lab and shop because of manufacturer's claims on performance (luckily the stuff was never installed in the field)

First
The internet It gives people the power to look for a solution to their problems without meeting or seeing the seller. These guys have something that does something really neat and is usually invented in their back yard or stolen from their students from a university. But does it work?(yes in the lab)

Stay away from fancy wordy web sites with lots of big words that you would have to watch StarTrek to understand I have a University degree but, if you can't understand me simply what did it teach me? Only to talk to other university grads. Look for customer support in the field and rates. Is it their President that will be doing it because of his great concern?

Second
Electro-flocculation does work

But every situation is different
How he will support you with real people in the field. If the seller of the goods doesn't ask for samples and a breakdown of what your needs or if he talks more than you (tell him it's milking time).

There are companies and people out there that know their stuff and really stand up to what they provide. But there are more flim-flam cons than drops in the sea.

Third
Tech is good ---But Who will be running this unit three guys making $120,000 a year "no" It will be a lower employee running the equipment And it has to be simple (light switch simple). Do Not Be Blinded by Lights

Four Costs
.002 per gal. But it's on a one acre lot in downtown Dallas And what about the guys making $120,000

The only reason I linked to this page was that I was researching the possibility that I could use Electro F to improve the speed our process For bilge water separation (it's very simple after the research) I have helped two companies (in the past) in the Vancouver area that use (Electro F) for waste treatment Thanks for the vent. Beware It just makes you a better customer

Cheers Dave

A. Good day

I have read with interest all the comments on EC going back to the 90's. I am involved in waste water treatment and have experimented with EC for a couple of years. It does work on a production basis. I never found a better way to break cutting fluid emulsions and industrial textile dyes. It is now 2006 and the men in white coats experimenting with EC have not been standing still. The problems in the past were not about "does it work" they were about cost effectiveness. We can now treat waste water for as little as 0.25 cents per 1000 gals and a energy consumption of between 3-7 watts per gallon.

EC is here to stay, you can reduce sludge in treatment water by 60% in certain cases, but the chemical guys would never agree.

I think we'd be delighted to see any list of articles you have, Matthew. But everyone has acknowledged lab success while the electrocoagulation proponents on this page are trumpeting field success, so impartial peer-reviewed articles assessing those field successes would be most interesting and convincing. Thanks!

A. Not knowing what everyone is interested in, I'd feel the best place to start when looking at the reputable literature on EC are two excellent recent review articles. Here are their citations:

Mollah, M.Y.A., Morkovsky, P., Gomes, J.A.G., Kesmez, M.., Parga, J. & Cocke, D.L. 2004 Fundamentals, present and future perspectives of electrocoagulation. J. Hazard. Mater. B114:199-210.

Holt, P.K., Barton, G.W. & Mitchell, C.A. 2005 The future for electrocoagulation as a localized water treatment technology. Chemosphere 59:355-67. Chem. Eng. J. 95:205-11.

These both contain numerous citations to the extant publications available. They also do well to lay out the challenges to overcome before EC becomes a reliable, widely-accepted technology.

Ed. note: Thanks very much Matthew!

A. I am currently researching EC at the University of Sydney, funded jointly by the Australian Research Council and a large multinational.

To answer your question Kamar, the surface area/volume ratio (specific surface area) is usually the area of the anodic surface / the volume of electrolyte in the reaction zone. Different methods are used however (e.g. total electrode area), so state the way you calculate it (if only everyone did this!).

All else equal, a higher specific surface area means a smaller reactor, higher practical flow velocities, and theoretically lower voltage requirement (though the latter is insignificant for highly conductive streams). Tradeoffs are fouling, shorting and maintenance complications.

Two other general EC papers I would add to Matthew's previous post are:

Chen, G. (2004). "Electrochemical technologies in wastewater treatment." Separation and Purification Technology 38(1): 11-41.

Jiang, J.-Q., N. Graham, et al. (2002). "Laboratory study of electro-coagulation-flotation for water treatment." Water Research 36(16): 4064-4078.

Ed. note: Thank you, Andrew.

We are currently using EC/EF to treat produced water from the oil and gas fields with great success. Flow rates at 10,000 bblpd. We are working on a white paper for release in March 2010 so keep in touch. EC works in this industry. I have documented results from various other industries as well.

Ed. note: Good to hear, Charles. Please send us some references from peer-reviewed journals. Thanks.

A. Hello:

For all of you with questions on whether EC (electrocoagulation) works or not. I can say that I have witnessed and also built these EC machines. I work for a company that currently holds the patents to the largest EC machine in the world. We have just finished a project in El Paso, Texas. On this project we are treating blowdown water from the cooling towers of a natural gas power plant. We are removing Silica from the water, currently treating water at about 802 gpm. This is called a ZLD (zero liquid discharge) facility. Thanks for your time.

A. I have been in Mexico City for the last 11 months working with a 50 GPM Electrocoagulation Unit. I have obtained amazing results in a wide range of industries. I have treated ground water from the Pemex ex refinery of 18 de Marzo in Mexico City that contained high BTEX concentrations. and was very successful results in the meat processing industries as well as the steel plant industry. We are currently setting up a 900 GPM system for a garment manufacturer to remove the blue dye that they use in denim and return the clean water to the customer for reuse. It is an amazing thing and can be a very cost effective way of treating a wide range of contaminants. (approx. $1.75 per M3). I have demonstrated this tech to many companies here in Mexico and have got a lot of positive response.