The Parisian public sanitation service (SIAAP, http://www.siaap.fr), created in 1970, is in charge of the management of the Paris conurbation wastewaters (8.5 million equivalent inhabitants). 1,925 people work directly for the SIAAP: workers, technicians, engineers and researchers. Many companies are working with the SIAAP for the plant construction or operation: Veolia, Suez and SAUR for the mains. Annual total budget is around 1.1 billion Euro, shared equally between construction and operating costs; In addition to salaries, operating costs mainly include energy consumption (pumping, aeration, etc.) and reagent consumption (iron salts used for physicochemical treatment).
SIAAP transports and treats around 2.5 million m3 of wastewater per day (around 30 m3/s). It operates the sewer network, i.e. 420 km of sewer mains (underground galleries with a diameter of 2.5 to 6 meters buried at a depth of between 10 and 100 meters) and storm water storage structures allowing the protection against flooding and the release of untreated water into the natural environment (total volume of 900,000 m3). Sewer network operation is done using Effluent Management Aid Model (MAGE). Six modern wastewater treatment plants, whose treatment capacities are comprised between 50,000 and 2,300,000 m3 per day, treat wastewaters. These WWTPs have high performances with a complete treatment of carbon, phosphorous and nitrogen. Due to the urban location, main of new compact technologies are used into these WWTPs, such as biofiltration, membrane bioreactors or lamellar settling tanks.