Process and installation for water purification with physico-chemical denitrificating sludges

摘要

To purify a raw water to be treated, for example sewage, containing organic pollution, suspended matter and nitrogenous pollution, - reactants are added in specific conditions to coagulate all suspended matter, including colloidal matter, in the form of physicochemical flocs and granules and, after the reactants, diluting water is preferably added in a flow rate ratio of at least 2/1, - the diluted flocculated water is circulated in a bed of sludge (8) consisting of such dense flocs and granules and of denitrifying bacteria, by subjecting this bed to a turbulent but intermittent stirring, and a denitrified effluent is recovered, - this denitrified effluent is circulated in a biological filter or preferably in a fluidised bed (26) containing nitrifying bacteria and into which oxygen or air is injected, and - a clarified effluent is collected, part of which is recycled to constitute the said diluting water.