Reuse of treated sludge from reed beds, first experience feedbacks of emptying and land spreading for some French wastewater treatment plants

Abstract

The sludge extracted from reed beds have mechanical qualities which exceed those of sludge of comparable dry matter content, making its spreading easier and homogeneous by manure spreaders equipped with vertical well sharpened cutters and turning at high speed. For DM content of 20 to 25%, these sludge could easily claim the status of solid and stabilized sludge according to the French regulation (for land spreading of sludge from wastewater treatment plants) that would allow temporary storage on plots. The dissociation emptying-spreading would respect the ideal time to empty the bed(s) to schedule between July 15th and late August to benefit both the evapotranspiration and not to undermine the regrowth of reeds in the beds before winter without having to wait the end of the harvest on spreading plots.