More stringent standards for drinking water quality and a global trend towards resource degradation have driven research toward improving the performance of treatment plants. Filtration remains a key step for drinking water treatment, being effective for the elimination of turbidity, colour and microorganisms. SUEZ is focused on continuous optimization of filtration performances aimed at improving the filtered water quality and/or reducing operating costs (energy, chemicals, water savings…). To this end, various approaches have been considered including the optimization of pretreatments and the replacement of traditional granular media with new ones such as Filtralite^® products. Filtralite^® is composed of expanded clay aggregates whose particle size (0,5-8 mm) and particle density (1050-1800 kg/m³) can be specifically selected. It offers innovative solutions to water facilities both for drinking water and wastewater as a goal of physical filtration or biological treatment. The use of this filter media concerns both the building of new plants and the refurbishment of existing plants. Today, Filtralite^® is implemented worldwide with references for biological treatment especially for denitrification. The performances of this media for particle retention has been less investigated. In this context, a study was conducted to answer the following key questions:

• What are the performances of Filtralite for particle retention in comparison with filter media commonly used on drinking water treatment plants in terms of filtered water quality and productivity?
• What is the impact of raw water quality on the performance of Filtralite media?
• What is the impact of filtration flow rate on the performance of Filtralite media?