Wastewater treatment plants for small communities: five attached-growth cultures on fine media

Francés. En France, ou l'on compte un grand nombre de petites collectivités, les communes rurales utilisent souvent, pour leur épuration des filieres telles que la boue activee ou le lagunage naturel. Les filieres" cultures fixees sur supports fins", simples d'exploitation, permettent d'elargir l'éventail des techniques d'epuration. Le but de cet article est de présenter ces filières caractérisées par une charge organique surfacique faible et un alimentation alternee des reacteurs conduisant a une auto-regumlation de la biomasse. La qualité de l'effluent atteint 90 mg/l de DCO, la nitrification est quasi-complète. Les teneurs en nitrates sont variables, selon les cycles d'alimentation. / France counts a large number of communities with less than 2000 inhabitants. The adjustment of wastewater treatment plants, easy to implement and to use, needed by these rural communities, enlarges the number of processes already widely used, such as waste stabilisation ponds and activated sludge. The purpose of this article is to describe the five wastewater treatment systems called "attached-growth cultures on fine media". A high and reliable quality level is obtained by supplying very small organic loads and an alternate feeding of the reactors leading to self-regulation of the fixed biomass( these sewerage plants don't have any secondary settlement tank). The effluent's quality reaches 90mg.l-1 COD. The nitrification is almost complete(NK-N<10mg;l-1). Nitrate contents are variable depending on feeding cycles and can be important.