Electro-Coagulation and Electro-Oxidation:
Electricity + Water = Electro-Chemistry Magic
by Rami Elias Kremesti M.Sc., CSci, CENv, CWEM
© 2025 Kremesti Environmental Consulting Ltd
Introduction:
Electro-coagulation and electro-oxidation are an exciting branch of water treatment that fall under the Electro-Chemistry branch of science where DC power interacts with water and its solutes. When i was in High School we learned about the electrolysis of water. Just attach two graphite electrodes to a DC power supply and insert in water. H2 is produced at the negative Cathode where H+ ions are reduced to Hydrogen gas, and this is verified with the pop test when a flame is applied to the gas. O2 gas is produced at the positive Anode where OH- ions are oxidized or the anode dissolves into solution. Thus water is split to form H2 and O2 or you generate H2 and coagulant. To think that this is the same chemical reaction that is used on the ISS and in Nuclear Submarines for astronauts and submariners to breathe !!! Wow !!!
Something else interesting happens: if the electrode is not inert like Graphite or Titanium, iron/aluminium, Ferrous (or Al+3) ions are also released into the solution which turns a beautiful blue due to the formation of Fe(OH)2. These cations can be used as coagulants to purify water.
In high-school, we were crazy enough to the try this experiment with an exposed Copper wire and AC current too !! The reaction is very violent and the water turns into a turquoise blue due to the formation of Cu(OH)2.
CAUTION: Do not perform this experiment at home without a proper Risk Assessment and adult supervision.
History
The history of electro-chemistry makes for some very interesting reading. It all started with Alessandro Volta who invented the first DC battery called a pile back in the day in the 19th century. And yes the word and unit of measurement Volt is named after him.
Luigi Galvani’s frog experiment from the 18th century involved observing a dead frog’s leg twitch when it touched an iron railing with a brass hook, which he initially believed was proof of “animal electricity,” a life force within the body. He later realized, through further experiments, that the twitching was caused by a chemical reaction between the metals and the frog’s body fluids, acting as a type of primitive battery. This discovery, which showed that electricity could be produced through chemical interactions, was named galvanism by Alessandro Volta, who built on Galvani’s work to invent the first battery. The Galvanic cell is named after Luigi.
Michael Faraday, Sir Humphry Davy and Svante Arhenius later developed the amazing electro-Chemistry and some of the first pure metals were isolated and generated electro-chemically. There is a lot more to read about this topic which you can find in the References links down below.
It is interesting that Electro-Chemistry has a strong Italian history and this remains to this day with the emergence of global leaders in the field of electro-Chemistry like De Nora.
Applications
We all know that batteries generate DC power. What happens when we apply DC power to water with various chemistries, opens up a fascinating world of applied electro-chemistry. One of those large scale industrial applications is chrome/zinc plating or similarly extracting metals from dissolved earth ores like Copper, Silver and Gold. Electro-Oxidation of PFAS is becoming more and more mainstream as the high tech electrodes are beginning to be produced at scale. Electro-chemical generation of Sodium Hypochlorite from Brine solutions is another widespread application used in disinfection. Some swimming pools are touted as being liquid chemical free. They use brine and electricity instead.
Chlor-Alkali Process
DC current and electrodes are also used in the Chlor-Alkali process: a concentrated brine NaCl solution is electrolysed and Na metal is produced this time on the Cathode and Cl2 gas at the anode. The Na metal reactions with water to form NaOH and H2 gas. All three are useful industrial substances. We at KEC are promoting the application of the Chlor Alkali Process for sustainable chlorine production in water treatment plants. We call the process TroisEau.
Figure 1: Chlor Alkali Process
Electrochemical Production of Ozone
Electrochemical ozone production (EOP) generates ozone (O₃) by applying an electric current to water at a suitable anode, oxidizing water molecules to form ozone, which competes with oxygen (O₂) production. High anode overpotential for the oxygen evolution reaction and high current densities are used to favor ozone formation. Materials like boron-doped diamond BDD electrodes are used for their high stability and over-potential, enabling the efficient production of ozone directly in water without requiring external UV irradiation or corona discharge, making the process compact and advantageous for applications like water treatment. Companies like BES offer this technology which involves membranes.
Applications of Electro-Coagulation:
Electro-Coagulation is a liquid chemical free way to dose Ferrous/Ferric/Al+3 cations into a polluted water stream to effect coagulation/flocculation to remove Suspended Solids, Phosphate and Heavy Metals. It has also been used to neutralize mining acidic waste waters by using Magnesium anodes that dissolve and form MgOH2 in solution. Some papers allege that electro-coagulation can also remove hardness ions, silica and fluorides. It could be a new pre-treatment method for Reverse Osmosis systems. Another potential application is in treating anaerobic sludge which might benefit from the inherent Hydrogen dosing.
A nice schematic of the electro-coagulation process is depicted below:
Figure 2: Electro Coagulation Schematic
The ferrous and aluminum ions produced at the Anode are coagulants and they help to remove suspended solids from water as well as break emulsions. The hydrogen produced in the form of fine bubbles at the Cathode lifts some of the suspended solids in the water to the surface of the water in a process similar to DAF = Dissolved Air Floation.
Advantages of Electro-Coagulation:
The advantages of electro coagulation are that it is a form of production of a coagulant without using chemicals. It also has another very important advantage: chemical coagulants such as FeCl3 and Al2(SO4)3 add chloride or sulphate ions to the water which increase the TDS and at the same time they make the water more corrosive to steel. This advantage also results in electro-coagulation producing less sludge that traditional coagulation. Additionally, because chemical FeCl3 hydrolyses water and produces acidic H+ ions, the alkalinity of the water is affected and the pH decreases after the coagulation step.
With Electro-Coagulation, the pH increases a little bit since H+ is reduced, OH- is released and this helps to precipitate heavy metals in the water for example in the case of treating Mine Waste water.
Another interesting aspect of electro-coagulation with Iron electrodes is that the ferrous ions produced can be used to catalyse the famous Fenton’s Reagent where H2O2 hydrogen peroxide is added to the water. This can help oxidise COD in the water. It is one of the oldest chemical forms of AOP = Advanced Oxidation Processes.
Other Types of Electrolysis: Electro-Oxidation
Using electrodes such as Boron Doped Diamond (BDD) results in more fascinating chemistry: Since the electrode is inert and does not dissolve, Hydorxyl radicals can form which are excellent at oxidizing organic pollutants.
Certain types of electrolysers are designed to generate Oxygen for breathing applications. Treadwell Corporation is one of those companies.
MMO = Mixed Metal Oxide electrodes are also very interesting and used in electro-Chlorination. They preferentially oxidise Chloride ions to form Chlorine/Hypochlorite.
The Achilles heal of these processes are the high cost of the electrodes. I personally worked at a sea-facing power station in North Africa where the heat exchanger of the condenser was disinfected using Hypo-Chlorite generated using sea water and DC current.
Experience with Electro-Coagulation
Treatment of wastewater and wash water by EC has been practised for most of the 20th century with increasing popularity. In the last decade, this technology has been increasingly used in the United States, South America and Europe for treatment of industrial wastewater containing metals. It has also been noted that in North America EC has been used primarily to treat wastewater from pulp and paper industries, mining and metal-processing industries. A large one-thousand gallon per minute cooling tower application in El Paso, Texas illustrates electro-coagulation’s growing recognition and acceptance to the industrial community. In addition, EC has been applied to treat water containing foodstuff waste, oil wastes, dyes, output from public transit and marinas, wash water, ink, suspended particles, chemical and mechanical polishing waste, organic matter from landfill leachates, defluorination of water, synthetic detergent effluents, and solutions containing heavy metals. Electrocoagulation is not typically used for domestic wastewater treatment, although some suppliers like FujiClean are using electrodes to remove residual phosphorus.
The Achilles Heal of Electro-Coagulation
Electro-Coagulation suffers from some serious drawbacks that need to be addressed before venturing into applying this technology on an industrial scale. Among these I list the following:
- The electrodes foul and get oxidised at which point the resistivity increases and the current and thus efficiency decrease. This can also lead to fluctuations in dosage rate.
- The efficiency of the process (Faradaic Efficiency) is dependant on high conductivity. In the absence of high TDS, the power consumption becomes prohibitive and this sometimes necessitates salt dosing. Water without minerals has a high resistance and energy is lost as heat.
- High cost of some over engineered reactors.
- Sometimes chemicals are still needed for removal of oxides on the fouled electrodes. Chemical cleans are sometimes part and parcel of maintenance. So the claim that it is chemically free becomes dubious.
- The process inherently produces Hydrogen which makes the ORP of the reactor positive. Ferrous is predominantly produced which does not produce good flocs. This sometimes necessitates an aeration or oxidation step which increases the cost of the process.
- Production of coagulant as Ferrous leads to carry over in the effluent which can be an issue for pre-treatment of systems like RO or can impact the regulatory permit for discharge to sensitive aquatic environments.
Parameters to Control
In Electro-Chemistry there are many parameters to control. To start with, we are working with electrodes to which a DC Voltage or Potential Difference is applied. The solution has a specific resistivity based on the chemistry and distance between the electrodes, and the V = R.I equation applies known as Ohm’s Law. The materials from which the electrodes are made is a very important factor that determines which reaction takes precedence for example liberation of O2 or Cl2. Faraday’s Law applies which equates the quantity of charge (amperes) with the chemical reactions occurring. Finally there is the complex chemistry of the solution where various reactions compete thermodynamically and kinetically. From a process point of view, chemical dosage is important which depends on the current density which is current per surface area. The pH of the solution is sometimes a factor to take into consideration too. Conductivity is important as electro-coagulation is challenging under low conductivity conditions because the resistance becomes too high.
Companies that Specialize in Electro-Coagulation and Electro-Chemistry
De Nora is one of the giants when it comes to Electrolytic production of Hypochlorite, they are one of the pioneers of that process. I once worked on a power station in Algeria that was built by ALSTOM and they disinfected their sea water condenser heat exchanger with Sodium Hypochlorite generated from sea water. The system was a De Nora system that vented the Hydrogen into the air. I still remember that the electrodes can form a crust and they need occasional acid cleaning.
One other company that specializes in electro oxidation is Arvia in the UK. They focus on trace pharmaceuticals and pesticides.
Another company that specializes in Electro-Coagulation is Power and Water. This company manages the fouling issue of anodes with Sonication or ultra sound acoustics to create cavitation.
The big water treatment companies such as Veolia and Nijhuis also have electro-coagulation systems.
Both Nijhuis and OVIVO have Electro-AOP systems too.
Lummus is also one major player when it comes to Electro-Oxidation and they build on their expertise with the ZimPro process.
WSP has commercialized a PFAS electro-oxidation technology too.
Aclarity is another one.
The Chinese are catching up on this technology with companies such as Boromond. They are trying to produce MMO and BDD electrodes cheaply.
Manufacturers of Specialty BDD Electrodes
Several companies in Europe manufacture boron-doped diamond (BDD) electrodes. Key players include CONDIAS GmbH in Germany, Neocoat SA in Switzerland, Pro Aqua Diamantelektroden Produktion GmbH in Austria, and De Nora Ltd in Italy. These companies offer a range of BDD electrodes tailored for various applications, including industrial water treatment, electrochemical processes, disinfection and biomedical devices.
Manufacturers of Mixed Metal Oxide MMO Electrodes in Europe
De Nora (Italy): A major global supplier with a significant European presence, De Nora was the first company to commercialize MMO-coated electrodes. It manufactures electrodes under the DSA (Dimensionally Stable Anodes) brand for various electrochemical applications.
Permascand (Sweden): This company is a leading provider of dimensionally stable anodes (DSA), including MMO-coated electrodes and electrolyzers. They have over 50 years of experience serving various electrochemical industries. Aquired by Chinese Magneto.
Jennings Anodes UK Limited (UK): A manufacturer that provides a range of MMO-coated titanium anodes, including rods, wires, and meshes, for impressed current cathodic protection (ICCP) and other applications.
METAKEM GmbH (Germany): Specializes in electrochemistry and precious metal chemistry, providing mixed metal oxide anodes for various industrial applications.
Insoluble Anode Technology B.V. (Netherlands): A manufacturer of both MMO and platinum-coated titanium anodes, located in the Netherlands.
Market Size of Electro-Coagulation and Electro-Oxidation Technology
The global electro-coagulation market is experiencing significant growth, driven by stricter environmental regulations, the demand for effective wastewater treatment, and technological advancements. While market size and CAGR vary by report, recent data suggests the market was valued at approximately USD 0.56 to 2.3 billion in 2024-2025 and is projected to grow at a compound annual growth rate (CAGR) of 7.8% to 10.5% between 2025 and 2033, reaching USD 1.12 to 7.8 billion.
The global electro-oxidation market is poised for robust growth, with projected sizes ranging from USD 1.6 billion in 2025 to USD 2.1 billion by 2030, growing at a CAGR of approximately 6% according to some reports, while others forecast an even faster growth to USD 2.5 billion by 2033 with a CAGR of 9.2%. This expansion is driven by the increasing demand for sustainable, chemical-free water and wastewater treatment, regulatory compliance, energy efficiency, and innovations in electrochemical processes, particularly for challenging contaminants like PFAS chemicals.
Conclusion
Electro-coagulation and Electro-Oxidation are fascinating areas of water treatment. However, once must look at and understand the basics of the chemistry and physics of the processes and understand their strengths and weaknesses before embarking on embracing the technology. As the technology matures, the commercial cost of implementing it will go down and we may see a more widespread implementation of this new CleanTech.
References
https://www.kwrwater.nl/wp-content/uploads/2021/03/TKI-Electrocoagulation-report_FINAL-.pdf
https://www.nature.com/articles/s41598-023-42831-6
https://en.wikipedia.org/wiki/Electrocoagulation
https://en.wikipedia.org/wiki/Electrochemistry
About the Author:
Rami Elias Kremesti is a chartered British water treatment expert residing in the UK. He earned his M.Sc. in Industrial Chemistry from the USA. Rami worked 10 years on power stations worldwide as a chemistry and water specialist and he has experience in industrial waste water treatment, sewage treatment, Reverse Osmosis, Cooling Tower chemistry, potable water treatment and is passionate about mitigating climate change using chemistry. He enjoys spending time with this daughters, cooking, playing guitar and spending time in nature. He has authored three books in practical philosophy: The Other Cheek of Islam, For Love of The Sacred Awe and MegaloPsychia.
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Rami Elias Kremesti Portrait