The treatment of septic tank sludge: in a purification plant or in beds planted with reeds?

Abstract

Taking in account the obligation of regulatory control of on-site wastewater treatment of dwelling houses, communities are now facing larger volumes of septage whose treatment should be studied and assured. In this context, Cemagref undertook studies to better characterize this septage and optimize its treatment upstream of wastewater treatment plants by activated sludge in extended aeration. We give the key factors and opportunities offered by an aerated and mixed storage capacity that minimize the impact of the significant pollution load of septage. Its dehydration on sludge drying beds planted with reeds without addition of flocculation agents is also discussed, and we then present another technique of pretreatment by stirring septage and mixed liquor which significantly improves the quality of percolates as shown by the first results obtained from pilot experiments not yet fed with the planned loads.