Tag: on site

Electrochemical chlorine generator preferred for dairy process water disinfection

Control chlorine residual and minimize chlorate

Posted on by Paul

One on-site generator solved multiple problems

Our New Zealand distributor  – Visentia was approached by a dairy processor in New Zealand, to provide a disinfection solution for their process water (used for washing and as an ingredient in their infant formula product).

Two problems existed:

Chlorination of municipal potable supply to factory not reliable

Chlorine residual varied between 0.00 and 1.50 ppm. The customer required very good control of chlorine residual to ensure consistent disinfection performance.

Exisiting disinfection method created too much chlorate by-product

Extremely low chlorate is required in the water and product. Chlorate is a precursor for perchlorate and the presence of either compound is anathema. A previous supplier had sold them a 2-chemical chlorine dioxide generator to improve disinfection, but they had not considered the impact on chlorate formation. Chlorine dioxide reacts slowly with residual chlorine to form chlorite and chlorate. Chlorine dioxide reacts with organic and inorganic demand to form chlorite and chlorate. Some 2-chemical generators produce chlorate in the reactor and chlorate is present in the chlorite precursor. The result – too much chlorate.

Options they considered:

  • Electricide® CDE electrochemical chlorine dioxide generator. The customer already had this generator on site for a different application. Trials were conducted using the 2,000 ppm ClO2 solution to disinfect the water. Result: lower chlorate than the 2-chemical generator, but not low enough to be acceptable.
  • Liquified chlorine gas. They did not want to store chlorine in drums or cylinders on site.
  • 12.5% sodium hypochlorite (bleach). High concentration of chlorate in freshly produced bleach and quick degradation in storage to form more chlorate. This option would only increase chlorate in the water.
  • Calcium hypochlorite. Running cost is too high.
  • Electricide® HG-10-G On-site chlorine generator using Electricide-B1 brine feed. This option ticks all the boxes. Chlorine gas is generated on-site and dosed into the process water main, prior to a large water storage tank. No storage of Dangerous Goods and low running cost. Zero addition of chlorate to the water.

Result

The HG-10-G chlorine generator was installed and has been operating for 12 months. Chlorate concentration in treated water after the generator is extremely low. Chlorine residual is maintained at 0.45 ppm when the free chlorine concentration in the muncipal supply is less than this value. When the muncipal supply concentration is greater than 0.45 ppm, the HG generator is idle. Overall, an excellent outcome.

What is the Electricide® HG Chlorine Generator?

The Electricide® HG chlorine generator is an electrolytic system for converting sodium chloride (salt) into chlorine. Electricide-B1 is a purified brine precursor that is fed into the HG generator at the anode side of the electrolytic cell, where chloride ion is oxidised to chlorine. Chlorine gas is extracted under vacuum and dissolved into water using a booster pump and eductor. Chlorine gas reacts with the water to form HCl and HOCl.  The generator is configured to accept either salt (NaCl) in 20 kg bags or Electricide-B1 solution. The generator is skid mount and easy to install on site.

Chlorine Generation Reactions:

① Anode (oxidation): 2Cl– → Cl2 + 2e–

② Cathode (reduction): 2H2O + 2e– → H2 + 2OH–

Chlorine gas is extracted from the anodoe solution (anolyte). NaOH at the cathode (catholyte) is either wasted or re-used for pH correction.

What is good about it?

  • Safety. Only one precursor chemical is required – Salt (NaCl) brine solution and this is non-hazardous. Chlorine gas is produced directly at the generator, on demand and is not stored. It is creation of chlorine gas from a non-hazardous precursor.
  • Stability. There is nothing to degrade. Brine precursor is stable in storage and chlorine gas is generated fresh on demand.
  • Purity. The chlorine gas produced by the HG generator adds zero chlorate, sodium and chloride to the water. This can be important for food production where low chlorate and perchlorate in the food product are important.
  • Simplicity. The generator is simple to operate, install and maintain.
  • Remote access. Web server access using any browser is standard with email alarms.
  • Reliability. High quality components and controlled precursor purity equals excellent reliability.

Interested?

The Electricide® HG generators are available for purchase or rental, direct or through our distributors.

Generators are configured to use vacuum purified granular salt or Electricide-B1 solution.

In most cases, you can install and commission the generator with remote assistance (web or phone). Dioxide Pacific can install and commission the system if desired. Installation is a simple process for mechanical and electrical technicians.

Download the Brochure pdf-icon-aa-30x30

Download the case study pdf-icon-aa-30x30

Contact us for more information or a quotation.

Generate Hypochlorite from Salt – Safe and Clean in Food Environment

Safety concerns with using 12.5% sodium hypochlorite

Posted on by Paul

Safety is always a concern to plant managers

Recently, we received an inquiry from a customer indirectly servicing the food industry. Their water is used for washing and must be clean and disinfected. They were looking for a disinfection method that would minimize their safety risk on site. Filtration+UV was chosen as the primary method although they realized it would not be sufficient on it’s own as the reticulation pipework would require a chemical residual of either chlorine (hypochlorite) to prevent biofilm growth.

Chlorine Considerations

This is how the customer perceived the various alternatives:

What is the Electricide® HGB Hypochlorite Generator?

The Electricide® HGB chlorine generator is an electrochemical system for converting sodium chloride (salt) into chlorine. Electricide-B1 is a purified brine precursor that is fed into the HGB generator at the anode side of the electrolytic cell where chloride ion is oxidised to chlorine. Chlorine combines with the hydroxide formed at the cathode to make sodium hypochlorite solution at 5-25 g/L (as NaOCl). The generator is skid mount and easy to install on site. Electricide-B1 chemical is available ex stock from Dioxide Pacific.

Chlorine Generation Reactions:

① Anode (oxidation): 2Cl– → Cl2 + 2e–

② Cathode (reduction): 2H2O + 2e– → H2 + 2OH–

① + ② (combined) 2Cl– + 2H2O → Cl2 + H2 + 2OH–

Chlorine reacts with caustic catholyte to form sodium hypochlorite and salt.

Cl2 + 2NaOH → NaCl + NaOCl

What is good about it?

  • Safety. Only one precursor chemical is required – Electricide-B1 and this is non-hazardous. The hypochlorite solution produced is 5-25 g/L at pH 9 – 9.5. This compares with commercial bleach at 12.5% (125 g/L) at pH 12. The lower concentration hypochlorite is much safer to handle and store.
  • Stability. The lower concentration hypochlorite produced by the HGB generator is 25 times more stable in storage than commercial bleach. Longer life means lower cost.
  • Purity. The hypochlorite solution produced by the HGB generator is extremely low in chlorate, sodium and chloride. This can be important for food production where low chlorate and perchlorate in the food product are important.
  • Simplicity. The generator is simple to operate, install and maintain.
  • Remote access. Web server access using any browser is standard with email alarms.
  • Reliability. The generator membrane cell is guaranteed when Electricide-B1 is used as the precursor.

Interested?

The Electricide® HGB generators are available for purchase or rental. Rental can include maintenance.

Electricide-B1 chemical is available in IBC’s (totes), 200L (55 gal) or 15L (5 gal) drums.

Dioxide Pacific can install and commission the system if desired. Installation is a simple process for mechanical and electrical technicians.

Download the Brochure pdf-icon-aa-30x30

Contact us for more information or a quotation.