Closed-cycled water overflow in “Sports Bay”
About this good practice
Each pool has overflow gutters by which the water splashed out of the pool volume is returned to a tank in the pool basement. The pool basement tanks are covered to prevent evaporation of the contents.
The water in this closed cycle is disinfected and filtered with positive-pressure auger filters that comprise a total of approximately 200 cartridges.
The water is fed into the filters under positive pressure and treated while passing layers of diatomic earth deposited on the fabric which surrounds the filter auger part.
Downstream of the filters, the water is chlorinated with a chlorine compound produced on site with an electrolyser, which forms a salt bridge and chlorine gas from NaCl; this form of delivery is much more efficient than liquid chlorine compounds.
Next, the chlorinated water is passed under an UV lamp. The UV lamp provides photo-oxidation-driven disinfection, which efficiently neutralises and inhibits the growth of bacteria, viruses and other microbes.
Finally, the water is recycled back to the pool via a system of piping and pool bottom inlet nozzles (with a total number of approximately 100 units). A pool with a total service capacity of 3,300 m3 has 3 to 4 full water changes a day.
The water lost by evaporation, carried out on the bodies and splashing amounts to approx. 100 m3 a day is replenished from the district mains; this make-up water is already treated.
The swimming pool water quality is monitored online.
Expert opinion
This good practice highlights the water reuse potential of European sport facilities, where a sustainable approach towards resources management should be increasingly supported in light of the policy challenges presented by the European Commission in the new Circular Economy Action Plan. Combining the use of diatomaceous earth filtration and UV lamps as key components of a closed cycle, the Campus of the Lodz University of Technology has achieved measurable water savings and enhanced the hygiene standards of its swimming pools. While the replicability of this good practice is undisputed, it should be noted that its implementation requires specific technical skills and adequate investment capacities.
Resources needed
The investment cost was about PLN 130 million (EUR 29.5 million)
Evidence of success
Unlike most swimming pools in Poland and the world, water disinfectant is produced on site by membrane electrolysis from a salt solution. The resulting disinfectant (gaseous chlorine) has 80 times higher effectiveness than the commonly used sodium hypochlorite.
100 m3 a day is replenished from the district mains; this make-up water is already treated.
The technologies used allow to achieve reused water quality exceeding the standards for drinking water.
Potential for learning or transfer
This kind of investment is possible to be carried out everywhere, taking into account the costs and high competence of those responsible for implementing the technology.
For the investment to be successful it may be necessary for many entities to work together. The "Sports Bay" has been financed by resources from the Łódź University of Technology, Łódzkie Voivodeship, the Łódź City Hall, Ministry of Sport and Tourism and the Ministry of Science and Higher Education.
Further information
Website
Good practice owner
You can contact the good practice owner below for more detailed information.
TUL Sports and Education Centre “Sports Bay”