THE ENHANCED ANAEROBIC DEGRADABILITY AND KINETIC PARAMETERS OF PATHOGENIC INACTIVATION OF WASTEWATER SLUDGE USING PRE- AND POST-THERMAL TREATMENTS PART 2. MEJORAMIENTO DE LA DEGRADABILIDAD ANAEROBIA Y PAR ´ AMETROS CIN ´ ETICOS DE LA INACTIVACI ´

In Mexico, wastewater sludge is characterized by high concentrations of organic compounds and pathogenic microorganisms. This study proposes the development and comparison of the anaerobic digestion enhanced with thermal pre-treatment denominated Pre-anaerobic digestion (Pre-AD) and with thermal post-treatment denominated Post-anaerobic digestion (Post-AD) processes for treating wastewater sludge. Additionally, the results from a kinetic model that was developed for thermal inactivation were used to describe the inactivation of faecal coliforms, Salmonella spp. and helminth ova during the thermal treatment stages. In the Post-AD operational batch test, it was determined that a period of 27 d was necessary to reduce the volatile solids (VS) by 38% at an organic loading rate of 0.65 kg VS m 3 d 1 . When the Pre-AD process was evaluated, 13 d of treatment was su cient for meeting the stabilisation criteria at an organic loading rate (ORL) of 1.25 kg VS m 3 d 1 in the batch test. In a semicontinuous operation tests, the Pre-AD process could be operated at an OLR of 3 kg VS m 3 d 1 , while the Post-AD process could only be operated at an OLR of 1.5 kg VS m 3 d 1 . The bacteria and