Process for treating sludge from septic tanks.

摘要

1. Method for the biological processing by activated sludge of night soil or septic tank sludge, having the following characteristics : dry material : 6-40 Kg/m**3 volatile material : 65-80% of dry material DBO(5) : at least 5-15 Kg/m**3 DCO (bichromate) : 10-45 Kg/m**3 of the type where the said septic tank sludge or night soil undergoes a biological activation process with a gas having a high oxygen content of at least 5% in volume for a duration of at least 5 hours, characterised in that at the start of the process the septic tank sludges to be processed are seeded with an activated sludge, emanating from a station for waste water biological processing by the activated mud process, said mud having a dry material content of 6 to 15 Kg per m**3 , the rate of seeding being at least 0.6 Kg of dry material per m**3 of sludge to be processed, and in that the said seeded septic tank sludges are submitted to the said biological oxidation process with a mixing energy and an output of the said high oxygen content gas such that the content of oxygen dissolved in the said septic tank sludges is at least 109/m**3 and in that furthermore the processed septic tank sludges are continuously decanted, producing on the one hand a decanted biological sludge having a Mohlman index comprised between 30 and 60 and a clear filtrate having a DBO of 0.3 to 2.5 Kg/m**3 and a DCO of 0.5 to 4 Kg/m**3 , the quantity of oxygen being introduced being less than 0.5 Kg per Kg of dry material introduced.