PERFECTIONNEMENTS APPORTES AU TRAITEMENT D'EAUX USEES SELON LES PROCEDES PAR BOUES ACTIVEES

摘要

The invention concerns a method for controlling the retention time of sludge clarification in a waste water treatment process using activated sludge comprising a step which consists in recycling the activated sludge from the clarification step to biological tanks. The invention is characterised in that it consists in modulating the recycling speed of the sludge (Qr) so as to obtain a constant concentration of the recycled sludge (Cr) while ensuring a retention time (TS) of sludge clarification less than a critical value (TS max).