FEED BACK OF THE OPERATION OF THERMAL PRE-TREATMENT ON WASTE ACTIVATED SLUDGE BEFORE MESOPHILIC ANAEROBIC DIGESTION
Delphine Nawawi1, Julien Chauzy1, Andrew B. Gilbert2 and Didier Cretenot1
1 Veolia Water Technical Department
2 Veolia Water Solution and Technologies
(free)
The BioThelys® process is the combination of a thermal hydrolysis pre-treatment and a
mesophilic anaerobic digestion with low residence time. The aim of this pre-treatment is to
enhance digestion by solubilising matter. The benefits for digestion are to improve volatile
matter reduction and so produce more biogas. This process has been chosen by three
French cities for their sludge treatment strategy: Saumur (60,000 pe), Château-Gôntier
(38,000 pe) and SIVO (80 000 pe). The purpose of this article is to describe the BioThelys®
system and to present the operating of the first references. The current operating conditions
are: a temperature of 160-170°C and a hydraulic retention time of circa 30 minutes with
concentrated sludge between 12 to 16% dryness. The volatile matter reduction improved
thanks to the thermal pre-treatment is between 40 – 45 % for only biological sludge. Digested
sludge is dewatered up to circa 30 % DS without lime. These operating conditions lead to
high quality sludge: free of pathogens, stabilised, odourless with a good fertilising value.
This article will detail the operating of the two WWTP which have chosen this process and the
performance results obtained after one year of operation.
KEY WORDS
Anaerobic digestion, Biogas, BioTHELYS®, Sanitisation, Sludge, Thermal Hydrolysis
