Martín Díaz, JuliaRuiz Hernando, MaríaAstals Garcia, SergiLucena Gutiérrez, Francisco2020-05-032020-05-032017-020960-8524https://hdl.handle.net/2445/158438The capability of clostridia spores to act as pathogen indicators in sewage sludge treatment was investigated. Sulfite-reducing clostridia and E. coli levels were monitored during waste activated sludge pre-treatments (alkali and ultrasound) and its subsequent mesophilic anaerobic digestion. E. coli was maintained or reduced depending on treatment type and intensity. However, alkali pre-treatment (35.3 gNaOH/kg TS) by itself and alkali (157 gNaOH/kg TS) and ultrasound (27,000 kJ/kg TS) pre-treatments followed by anaerobic digestion provoked reproducible clostridia increases. Specifically, up to 2.7 log10 after 35.3 gNaOH/kg TS pre-treatment and up to 1.9 and 1.1 log10 after digesting the 157 gNaOH/kg TS and 27,000 kJ/kg TS pre-treated sludge, respectively. Having rejected the hypotheses of sporulation and floc dissipation, the most plausible explanation for these clostridia increases is re-growth. These results question the suitability of clostridia spores as indicators of sludge treatment and other biological treatments where clostridia may have a role.7 p.application/pdfengcc-by-nc-nd (c) Elsevier B.V., 2017http://creativecommons.org/licenses/by-nc-nd/3.0/esClostridiBacteris patògensIndicadors biològicsLlots de depuradoraClostridiumPathogenic bacteriaIndicators (Biology)Sewage sludgeinfo:eu-repo/semantics/article6666132020-05-03info:eu-repo/semantics/openAccess