title: Production of volatile fatty acids by fermentation of waste activated sludge pre-treated in full-scale thermal hydrolysis plants.
abstract: This work focuses on fermentation of pre-treated waste activated sludge (WAS) to generate volatile fatty acids (VFAs). Pre-treatment by high-pressure thermal hydrolysis (HPTH) was shown to aid WAS fermentation. Compared to fermentation of raw WAS, pre-treatment enabled a 2-5x increase in VFA yield (gVFA(COD)gTCOD(-1)) and 4-6x increase in VFA production rate (gVFA(COD) L(-1) d(-1)). Three sludges, pre-treated in full-scale HPTH plants, were fermented. One was from a plant processing a mix of primary sludge and WAS and the other two from plants processing solely WAS. The HPTH plants solubilised suspended matter, evidenced by a 20-30% decrease in suspended solids and an increase of soluble COD : total COD from 0.04 to 0.4. Fermentation of the three sludges yielded similar VFA concentrations (15-20gVFA(COD) L(-1)). The yields were largely independent of retention time (1 d-6 d) and temperature (42°C, 55°C). Also, the product spectrum depended mostly on the composition of the sludge rather than on operating conditions.
authors.affiliation: AnoxKaldnes AB Klosterängsvägen 11A, Lund, Sweden.
authors.forename: F
authors.initials: F
authors.lastname: Morgan-Sagastume
authors.forename: S
authors.initials: S
authors.lastname: Pratt
authors.forename: A
authors.initials: A
authors.lastname: Karlsson
authors.forename: D
authors.initials: D
authors.lastname: Cirne
authors.forename: P
authors.initials: P
authors.lastname: Lant
authors.forename: A
authors.initials: A
authors.lastname: Werker
mesh_terms: D001421:Bacteria, Anaerobic / Q000378:metabolism*; D005232:Fatty Acids, Volatile / Q000378:metabolism*; D005285:Fermentation; D006868:Hydrolysis; D007220:Industrial Waste / Q000517:prevention & control*; D012722:Sewage / Q000382:microbiology*
chemical_list: D005232:Fatty Acids, Volatile; D007220:Industrial Waste; D012722:Sewage