ANSES opinion on membrane processes for swimming pool water

On July 3, 2020, the ANSES published a notice concerning the use of membrane processes used for the filtration of swimming pool water.

There are two types of pool water contaminants:

- Particulate matter such as hair or dander.

- Dissolved organic matter such as urine or sweat.

Pool water must be filtered, disinfected and disinfected to ensure the safety of bathers.

The disinfection of public swimming pool water is carried out using chlorinated products.

Chlorine can react with dissolved particulate matter and compounds to form disinfection by-products (DBPs) that cause adverse human health effects such as skin and eye irritations and respiratory damage. Studies have also highlighted the carcinogenic and mutagenic properties of some by-products.

Appropriate water treatment to remove the precursors of DBPs and DBPs themselves should therefore be implemented to reduce the exposure of bathers and staff to these compounds.

Currently, sand filtration is the most common method used. It removes the majority of suspended solids (SS), especially if a coagulation/flocculation step is carried out upstream.

However, this technique used alone has its limits, as it does not systematically comply with the regulatory limits. In order to obtain basin water that complies with the legislation, the managers add new water beyond the 30L per bather and per day fixed by the regulations.

Membrane filtration processes provide an interesting alternative to sand filtration since it eliminates some of its negative effects.

The characteristics of membrane filtration processes offer an alternative to sand filtration of swimming pool water and make it possible to mitigate some of the negative effects noted above (greater retention of micro-organisms depending on the membrane selected, compactness of the systems, greater washing frequency, reduction in water consumption).

The ANSES defines membrane filtration as "a physical separation process in the liquid phase using a membrane that is both permeable and selective, described as perme-selective. This membrane, depending on its intrinsic characteristics and mode of use, constitutes a barrier allowing the transfer of certain compounds and the retention of others. »

There are four types of membrane processes: reverse osmosis, nanofiltration, ultrafiltration and microfiltration.

Each of these technologies is highly efficient and produces excellent quality water with much lower turbidity than sand filtration and better retention of microorganisms.

The different membranes can replace the filters currently used for the "clarification" of swimming pool water. However, with the aim of also eliminating the precursors of DBPs and the DBPs themselves, the ANSES recommends the implementation of a hybrid process (coupling several treatments and including in particular a stage/stage using activated carbon). On the other hand, these complementary treatments make it possible to preserve the characteristics of the membranes.

Please note that your Phytocontrol Laboratory is approved by the Ministry of Health to carry out sampling and analyses for the sanitary control of swimming pool water.

Do not hesitate to contact our customer service Dedicated line +33 800 900 775 or by email service-clients@phytocontrol.com