In-situ water treatment processes intend to improve water quality directly in the environment, upstream of water treatment plants (WTP). This can help to decrease the use of reagents and/or production of sludge in water treatment. The application consists of modifying the path of water before entering the WTP through the environment (water resources management) in view of creating a natural in-situ treatment plant. The Bi'Eau® process is an innovative process developed by Lyonnaise des Eaux and CIRSEE. The principle is to associate two (or more) underground systems in series to obtain an improvement of the raw water quality before final treatment: the first system is a river bank filtration providing treatment benefits from reducing conditions and an abundant recharge from a stream (well field along a river, alluvial quarry along a river); the secondary system is an artificial recharge scheme providing complementary treatment benefits from oxidizing conditions. The Bi'Eau® process helps to decrease the number of treatment steps, and to decrease the need of reagents and sludge treatment by eliminating most of the non-desirable compounds (iron, manganese, ammonia, suspended solids). It brings also strong guarantees on bacteriological issues. A double Redox barrier plays an important role in the natural elimination of pollutants (nitrates, metals, organic compounds...). The Bi'Eau® process has been granted two authorizations in France and is contemplated at several other sites around the world. The project restores the quality and the quantity of the resource in a sustainable way, with low investment and operation costs. Includes table, figures.
