Thermal hydrolysis pre-treatment has no positive influence on volatile fatty acids production from sewage sludge

• Published in: Bioresource technology 2023-05, Vol.376, p.128839-128839, Article 128839
• Main Authors: Castro-Fernandez, Ander, Taboada-Santos, Anton, Balboa, Sabela, Lema, Juan M.
• Format: Article
• Language: English
• Subjects: Bioreactors; Fatty Acids, Volatile; Fermentation; Hydrogen-Ion Concentration; Hydrolysis; Microbiology analysis; Microbiota; Sewage; Sewage sludge; Thermal hydrolysis pre-treatment; Volatile fatty acids
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2023.128839

[Display omitted] •Raw and thermally pre-treated sludge were compared in terms of VFA production.•In batch mode, pH 8 resulted the most favourable one for VFA production.•VFA yield in batch tests resulted lower when sludge was thermally pre-treated.•In continuous operation, raw and pre-treated sludge achieved similar VFA yield.•Microbial key-players were alike independently of applying thermal pre-treatment. The study compares the potential to produce volatile fatty acids (VFA) from sewage sludge, both raw and thermally pre-treated in two modes of operation. In batch mode, raw sludge at pH 8 obtained the highest maximum VFA yield (0.41 g COD-VFA/g CODfed) whereas pre-treated sludge achieved a lower value (0.27 g COD-VFA/g CODfed). The operation of 5-L continuous reactors showed that thermal hydrolysis pre-treatment (THP) did not have any significant influence on VFA yields, averaging 15.1 % g COD-VFA/g COD with raw sludge and 16.6 % g COD-VFA/g COD with pre-treated one. Microbial community analysis showed that phylum Firmicutes was predominant in both reactors and that the enzymatic profiles involved in VFA production were very similar regardless of the substrate fed.