Chemical-free water softening in Juelsminde

The pilot test in Juelsminde main objective is to remove the amount of the hardness that cause scaling in water heating system.

The scaling potential hardness that shall be removed in softening processes is different from a technology to another. In water softening technologies design and operation, it’s recommended to reach a CCPP at 90 °C below 0.6 mmol/L to avoid extensive lime scaling.

Pilot study objectives:

• Quantify scaling capacity of Juelsminde water drinking water resources
• Demonstrate the effectiveness of the technology
• Evaluate operating conditions
• Determine energy consumption
• Check limiting factors

In Juelsminde waterworks, we have decided to implement SUEZ ERCA² pilot plant which targets reducing the water hardness from 22 to 15 ^odH.

The Erca² pilot plant consists of:

• A reactor of 12 liters, stainless steel 316L reactor electrodes
• An electric generator (15V-10A) and connections
• Blowers and pipes
• Raw water pneumatic pump and flow meter
• A raw water 250 L tank
• Miscellaneous laboratory equipment for analysis: pH, TH, THCA, TAC conductivity

Equipment construction materials are high quality materials:

• Stainless steel range: 316 L and 304 L
• Titanium Ti 40 grade 2
• Iridium or Platine.
  

In the electro-softening process in the ERCA²-plant precipitation of scale occurs on an electrode surface as a consequence of the electrolysis reaction.

If the water between these electrodes is mixed, the ions H₃O⁺ and OH^- neutralize each other and the electrolysis would produce hydrogen and oxygen. However, if a separation is realized with a laminar flow close to the cathode, OH^- ions will convert bicarbonate into carbonate which in turn will precipitate with calcium.

The ERCA² electro-physic technology regulates its action with the raw water flowrate. Removal efficiency is continuously measured with a double conductivity captor on the raw and treated water at the same time. The system is not concerned by other parameters such as turbidity or pesticides, but it can remove heavy metals (Ni – Al – Zn …).

The ERCA² process has the specific and unique (patented) advantage of being a chemical - physical process which produces treated water for human consumption. Other advantages of the process are:

• Secured a protected water quality
• Automatic process
• Automatic scale extraction
• Continuous measurement for efficiency control
• Do not require the use of harmful chemicals
• Treated water is free from microbial pollutants
• Annual preventive maintenance for equipment control

We could see all benefits of ERCA² technology in Juelsimde and we were also able to achieve the target hardness of 6.8 °dH in hardness removal (visible red line in the picture below).

Electrolytic softening has already been installed for softening at more than 20 French waterworks over the past decade. Based on the experience from France and the pilot plant in Juelsminde, the technology is very easy to operate, requires minimum maintenance and there is no waste production. The only product is 95% calcium carbonate, which can be used for industrial and agricultural purposes.