Seine Aval UWWT Facilities Ready for Use

Bringing these facilities on line will help Seine Aval meet the regulatory standards set forth in the European Urban Wastewater Treatment Directive (UWWT), which requires elimination of 80% of phosphate-containing pollution and 70% of nitrogen-containing pollution. While the plant already complies with the phosphorous limits, the new equipment will enable it to reduce nitrogenous waste to the levels required by European regulations.

So, after two years of construction, these three new installations mark an important step toward improving water quality in the Seine River:

• Supplementary denitrification unit: This unit will allow Seine Aval to reduce total nitrogen by 70%, as required by the UWWT. It employs a biofiltration technique in which bacteria on polystyrene balls form a filtration system through which water flows from bottom to top. The denitrification stage is based on the ability of certain bacteria to use the oxygen contained in nitrates for respiration, thereby converting it to nitrogen gas, a natural component of air.
• Decontamination unit for sludge effluent: This equipment will optimise biological treatment of water. Wastewater arising from the treatment of sludge has a high concentration of nitrogenous waste (urine) and carbon-containing waste (faecal matter). Currently, it is reintroduced directly into the stream at the beginning of the treatment process, adding additional pollutants to the load in water entering the plant. The new unit will pre-treat the effluent before it is returned to the treatment pathway.
• Sludge thickening unit: At present, there is a direct connection between the settling ponds for carbon-containing wastes and the digesters used to treat sludge. Installing a thickening unit between these two facilities will make it possible to separately manage constraints on the elimination of carbon (accumulation of sludge in the ponds) and those related to the smooth operation of the digesters (adjustment of sludge volume to match the facility’s capacity). Ultimately, the unit will optimise the treatment of carbon and improve the treatment of sludge.

Nathalie Kosciusko-Morizet, the Minister of Ecology, Sustainable Development, Transport and Housing, was very pleased with the progress of the work. She congratulated SIAAP on the success of this project, which has enabled“the treatment plant to catch up, as the work done here takes it to a new level—from being merely an average player to being a leader—since the UWWT objectives have been achieved.”

Seine Aval is Europe’s largest wastewater treatment plant, handling daily over a million-and-a-half cubic metres of household and industrial wastewater as well as storm runoff.

BG is a long-term partner of SIAAP, having begun its work with the Seine Aval plant in 1995.

BG is part of the group responsible for designing and implementing UWWT compliance efforts. From 2003 to 2007, it helped construct the nitrification unit, the first stage in treating nitrogenous waste and the first phase of UWWT compliance.

From 2008 to 2011, BG participated in the second phase of UWWT compliance.

Finally, BG is a partner in the group responsible for implementing the new biological stream, which will begin in early 2012 with a 2017 completion date.

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