Réduction de la production des boues à l'aide d'ultrasons

Abstract

The study presented here has taken place in the light of a LIFE Environment project directed by the Water and Waste Water Service of Angers Loire Metropole. The treatment of a part stream of recycled sludge (Waste water treatment plants of 6300 population equivalents) has reduced sludge production by about 26 %. The treatment by ultrasounds seems to have no impact on the water treatment performance, on the quality of thickened sludge, neither on the direct emission of greenhouse gases. The only exception is a decrease of the treatment performance of phosphorus. The treatment is not valuable from an economical point for this small waste water treatment plant with low sludge handling costs (10 /ton). Extrapolation of the results show that after some modifications, the process could be economically feasible for waste water treatment plants with a sizee 100 000 population equivalent and with final sludge eliminution costs > 11 /ton (DM 20%). If a digestor is present, it is preferable to apply ultrasounds to the sludge file in order to increase biogas production. This final application has proved itself all over the world (Hein, 2008; Nickel, 2008)