Denitrification of effluent
October 1st 2007

Denitrification Looking round the Seine Aval plant you could be forgiven for not knowing you were at a wastewater treatment works at all.

Developments at one of the biggest and oldest plants in Europe are bringing Seine Aval into a new era, and forming a watershed in treatment reliability.

Situated in Achéres, France, the plant treats the wastewater generated by over 75% of the population in the Paris region. Its most recent development, the nitrogen pollution unit, is designed to further improve the quality of water returned to the river Seine and to meet EU environmental requirements laid out by the European Directive on Urban Wastewater.

Operating within the context of a broader environmental project, the unit is integrated architecturally with its surroundings and notably, is an odour-free facility.

Since 2002,OTV France, a subsidiary of Veolia Water, has managed the nitrification project, with the latest facilities commissioned in November 2006.

Veolia aim to achieve full nutrification and denitrification of all the effluent from the greater Paris area by 2015. The improved efficiency and performance of the latest plants are already being seen in the Seine's changing flora and fauna; 35 different species of fish have now been identified, compared with just two 15 years ago.

The latest treatment unit, built specifically to deal with nitrogenous pollution, removes all the ammonia and some of the nitrates from the water before releasing it into the Seine.

This is completed using compact biofiltration technology known as Biostyr.This process is capable of eliminating all biodegradable pollutants, from carbon (COD and BOD) to nitrogen (N-NH4 and N-NO3) and particulates (TSS).

The Seine Aval Biostyr process performs full nitrification of all effluent (transformation of ammoniacal nitrogen into nitrates) removes residual carbon pollution and retains suspended solids. The plant comprises 84 Biostyr filters with a total filtration surface of 15,000 m2.

Seine Aval's nitrogen unit is part of a wider ambitious environmental initiative that seeks more than wastewater treatment. The new facilities are designed to provide optimal operating reliability and are architecturally integrated in a way that provides scope for educational visits.