What is the Electrochlorination process?

Electrochlorination is the process of applying an electrical current to salt water to produce dilute sodium hypochlorite (bleach) and hydrogen gas. The resultant sodium hypochlorite solution contains between 0.7%-1% chlorine. This low concentration is considered non-hazardous to humans yet still destroys viruses, bacteria, and other harmful microorganisms present in the water, making it safe to drink and preventing the spread of diseases. 

Unlike other chlorination methods, such as chlorine gas or commercial hypochlorite solutions, electrochlorination doesn’t generate any toxic by-products, nor does it require staff to handle hazardous chemicals, such as chlorine or sodium hypochlorite in high concentrations. The only by-product is hydrogen gas and there are processes to manage and disperse this safely.

Electrochlorination is therefore a highly effective and economical technique for disinfecting water. Unsurprisingly, it’s used all over the world, at all scales, from personal electrochlorination units carried by campers in remote locations to giant industrial plants treating potable water for an entire city. 

Electrochlorination produces sodium hypochlorite on site on an “as needed” basis. If required, electrochlorination can function as part of a responsive system that automatically generates a dosage of sodium hypochlorite depending on the existing levels of free chlorine or organic matter in the water. Here at ProDose, we install electrochlorination apparatus ranging in dosing capacity from 25 grams per hour right up to 10 kilograms per hour.

What’s involved in the Electrochlorination Process?

In very basic terms, electrochlorination is the electrolysis of salt water. This can be natural seawater or artificial brine produced by adding sodium chloride, or pure vacuum dried salt, to fresh water. In all brine based systems the incoming water (used to dilute the brine and dissolve the salt) is softened.This reduces calcium and magnesium salts dissolved within the water and prevents the build up of harmful scale deposits around the electrical components and within pipes. This improves the reliability of the system.

After cleaning, the filtered brine flows through a series of electrodes within an electrolytic cell. A low voltage DC current is passed through the solution. At the positive anode, chloride ions are oxidized to produce chlorine. At the negative cathode, the salt water is reduced to sodium hydroxide and hydrogen. The liberated chlorine reacts instantly with the sodium hydroxide to produce sodium hypochlorite, while the hydrogen gas is released. 

The chemical reaction is:

NaCl + H2O + ENERGY → NaOCl + H2

The sodium hypochlorite solution flows onwards to a separate chamber or tank, where it is separated from the by-product, hydrogen gas.The sodium hypochlorite is typically low strength, with a moderate pH value. From here, it can be stored in the short term or immediately injected into the main water system where it goes to work, either as a continuous supply or a shock dose.

Safe Dispersal of Hydrogen

The by-product hydrogen is highly flammable and has no smell. Therefore it should not be permitted to build up in significant quantities around the electrochlorination equipment as it could explode. Some kind of degassing system needs to be built into the process to make sure the hydrogen disperses safely. Prodose advocates the use of dual containment and force air ventilation of all hydrogen containing components within a plant room. This ultra safe method ensures that in the event of a leak of hydrogen (cracked pipe or leaking fitting) the hydrogen is immediately diluted with air to a concentration significantly below the 4% explosive threshold.

Choosing an Electrochlorination System

The ProDose team of experts has specified and installed more than 100 electrochlorination systems in the UK and worldwide. Our experience covers a variety of industries and applications, from food production to school swimming pools to drinking water treatment. We offer a range of AMPRO electrochlorinators to suit every operation, footprint, and budget, and we always include a full after-sale support package.

• MPS Model – A simple wall mounted, lower capacity electrochlorination system, with self-cleaning electrode technology.
• MP Models– Available in three capacities these electrochlorinators feature auto brine dilution, hydrogen degassing and force air ventilation, all in one compact wall mounted assembly. With an intelligent colour touchscreen control panel, operators can access running parameters, help screens and system diagnostics with ease.
• MPI Models – Available in five larger capacities these floor mounted electrochlorinators are supplied fully assembled and ready for integration at site. These also feature auto brine dilution, hydrogen degassing, force air ventilation and intelligent touchscreen control panel as per the MP range.

Call us today to discuss your electrochlorination needs, whether you’re considering upgrading your existing system or installing an entirely new one.