La biofiltration des eaux usées : comparatif technique et économique de différentes configurations de traitement

Wastewater treatment by biofiltration: technical and economical comparison of different operating modes

SIAAP – Direction de la Recherche et du Développement 82 avenue Kléber, 92700 Colombes

Auteur de correspondance : vincent.rocher@siaap.fr

Abstract

Technical and economical approaches of municipal wastewater treatment by biofiltration are dealt with in this paper. The treatment outcome, which was assessed from the skill acquired through the operation of the Seine Centre plant (SIAAP, Colombes), evidenced the efficiency of both biological abatement of carbonaceous pollution and nitrification (NH₄⁺ → NO₃^-). The concentrations of oxidizable organic matter and ammonium in discharged water are far below the regulatory thresholds. On the other hand, the efficiency of the denitrification step (NO₃^- → N₂) depends on the operating mode being adopted. That reduction is comprehensive when the denitrification step occurs downstream from the treatment (downstream denitrification – exogenous carbonaceous substrate), whereas it is only partial when being integrated upstream from the treatment (upstream denitrification – endogenous carbonaceous substrate). Thus, the plant operation in a layout only including an upstream denitrification can be contemplated and the treatment should then be supplemented with a post-denitrification step (combination of upstream and downstream denitrifications). Investigating the operating costs revealed the economical feature of the treatment process combining upstream and downstream denitrifications. The plant performance in that configuration results in operating costs that are lower by 5-10% than the conventional system only integrating a downstream denitrification.