Safe water for Prague – CHLORINSITU® can be relied on
Supplying the Czech capital with high-quality drinking water is a daily challenge. Several modern electrolysis plants from ProMinent have been in operation since the beginning of the year to ensure that this functions smoothly.
Changeover to new disinfectant
Around 1.13 million people live in Prague, the capital of the Czech Republic. Supplying such a large city with clean drinking water is a challenging task. For this reason, those responsible at the waterworks decided to replace the chlorine gas with sodium hypochlorite in the existing big drinking water reservoirs. This process step should become safer, because the chlorine gas is a toxic gas and requires a special level of security and protection for its storage and handling.
Based on the positive experiences from a previous project with two installed electrolysis plants for drinking water reservoirs for over 130,000 people, ProMinent Czech Republic was once again assigned. No transport, no storage and no handling of hazardous chemicals, but the processing of harmless common salt into sodium hypochlorite directly on site with modern plant technology were the premises.
- Post-chlorination of drinking water for two 100,000 m3 reservoirs for around 800,000 inhabitants of Prague
- Changeover from chlorine gas to sodium hypochlorite as disinfectant
- Post-chlorination of an average of 3,000 litres of water per second with a concentration of free chlorine of 0.2-0.4 ppm
Electrolysis – economical and technically top
After an intensive planning phase on the part of ProMinent Czech Republic on behalf of the design company SWECO Hydroprojekt, a.s. for this so far largest system in the country, the complete plant was installed by the company Česká voda - Czech Water a.s. at the end of 2018 within three months. The commissioning took place in February 2019 together with the experts from Van den Heuvel Watertechnologie B.V. Four CHLORINSITU® III electrolysis units with a capacity of 2,500 g/h each build the heart of the plant. The further scope of delivery includes: Seven fully assembled DULCODOS® dosing systems, each with two Sigma X motor-driven diaphragm dosing pumps with integrated control and one dosing system with two delta® solenoid-driven diaphragm dosing pumps. In addition, a PE-HD tank for storing 4,000 litres of sodium hypochlorite solution, three chlorine gas warning devices with sensors and a central PLC system. The sodium hypochlorite economically produced in the CHLORINSITU® III systems by means of electrolysis, is feed by two metering systems to the two inlets of the two large reservoirs, five metering systems supply five reservoir outlets to the Prague water supply network and one system takes over the metering at the outlet to a nearby these reservoirs.
Project successfully completed
Thanks to careful planning and execution by experienced companies in the field of water treatment, the new electrolysis plants has been running flawlessly since commissioning. The Prague waterworks benefit from the economical and safe disinfection of drinking water. This is due to the high-purity sodium hypochlorite produced by the CHLORINSITU® III units with ADS system having a concentration of approximately 2.5-3.0% of free chlorine. In addition, there is very little carry-over of common salt from the membrane cell into the end product – a yield of more than 85%. Thus, the complete sodium hypochlorite solution, which is more stable and water-soluble than chlorine gas, can be supplied to the drinking water by means of separate dosing pumps.
The customer is very satisfied with the repeated use of ProMinent electrolysis systems and the responsiveness of the companies involved in the project. Therefore, the same suppliers were also entrusted with the maintenance and repair of the new facilities.
- Supply of clean drinking water to three quarters of Prague's population
- Successful changeover of the disinfectant to sodium hypochlorite
- Economical and safe production of disinfectant by electrolysis
- Reliable system control via Remote Control Engineer for remote diagnosis and troubleshooting
- Long service life of the membrane cells due to constant vacuum
- High operational safety of the CHLORINSITU® III systems through design as vacuum systems and equipment with ATEX-95-compliant ventilation system