Biomass of microorganisms used for treating wastewater from their pollutants (mainly organic matter). Microorganisms are free, suspended in the wastewater, kept inside an aeration tank, and feed on the pollutants. Then, the separation of activated sludge and water occurs in a clarifier: a part of the sludge is put back into the aeration tanks, while the other part (corresponding to the increase of stock) is discharged.
Municipal public utility in charge of conveying drinking water to the consumer's tap and collecting and treating wastewater and stormwater before returning them to the natural environment. The 30,000 French public water supply and sanitation services are also in charge of the relations with the consumer: information, demand management, billing, etc. The "drinking water supply" service includes the abstraction of water from the natural environment, its potabilization and supply. The "sanitation" service includes the collection, conveyance and treatment of wastewater and the disposal or reuse of sludge…
Contract by which a corporate body under public law entrusts the management of a public utility for which it is responsible to a public or private operator, whose remuneration is substantially linked to the result of the utility operation. The delegatee may possibly be responsible for building structures or for purchasing properties necessary for the utility. The fundamental difference between a public market and a public service delegation results from the method of payment chosen. For a public market, payment is made by the public buyer. For a public service delegation, remuneration derives from the operation of the utility, done at the delegatee's own risk.