Print Email Facebook Twitter Structural extracellular polymeric substances determine the difference in digestibility between waste activated sludge and aerobic granules Title Structural extracellular polymeric substances determine the difference in digestibility between waste activated sludge and aerobic granules Author Guo, H. (TU Delft Sanitary Engineering) Felz, S. (TU Delft BT/Environmental Biotechnology) Lin, Y. (TU Delft BT/Environmental Biotechnology) van Lier, J.B. (TU Delft Sanitary Engineering) de Kreuk, M.K. (TU Delft Sanitary Engineering) Date 2020 Abstract Aerobic granular sludge (AGS) technology is an alternative to conventional activated sludge to reduce the process footprint and energy consumption. Strategies for the efficient management of its produced biomass, that is grown in a granular morphology as well, need further development. Anaerobic digestion (AD) is commonly applied in waste activated sludge (WAS) treatment and is a potential option also for produced AGS treatment. In earlier studies, the biochemical methane potential of AGS was found lower than that of WAS both grown in full-scale municipal wastewater treatment systems. In order to understand this difference, this study aimed to investigate the anaerobic conversion of structural extracellular polymeric substances (SEPS), which is a type of gel-forming biopolymer, being responsible for the aggregation of sludge. Using WAS and AGS as substrates, a comparative AD batch experiment was performed for 44 days during which the SEPS fraction was extracted from both types of sludge. The changes in the SEPS chemical composition was analysed by Fourier transformed infrared spectroscopy and three-dimensional excitation and emission matrix analysis. In addition, the mechanical strength of hydrogels of extracted polymers cross-linked with Ca2+ ions was investigated by dynamic mechanical analysis. Results showed that the amount of SEPS was reduced by 26% in AGS (SEPSAGS) and by 41% in WAS (SEPSWAS), respectively. Polysaccharides and, to a lesser extent, the proteins in the SEPSAGS were more refractory compared to those in SEPSWAS. This resulted in a lower loss of the gel stiffness of SEPSAGS than that of SEPSWAS during the AD process. Moreover, the release of SEPS from tightly bound EPS to loosely bound EPS were observed in both types of sludge, but that in AGS exhibited a lower transition rate. The observed properties explain the distinct differences in anaerobic biodegradability, the slower decomposition of the sludge structure, as well as the better dewaterability of AGS as compared to WAS after the AD process. Subject Anaerobic digestionFull-scale Nereda® municipal wastewater treatment systemGel-forming propertyStructural extracellular polymeric substancesWaste aerobic granular sludge To reference this document use: http://resolver.tudelft.nl/uuid:9b9e7380-d565-4e91-b9f2-09be77d45415 DOI https://doi.org/10.1016/j.watres.2020.115924 ISSN 0043-1354 Source Water Research, 181 Part of collection Institutional Repository Document type journal article Rights © 2020 H. Guo, S. Felz, Y. Lin, J.B. van Lier, M.K. de Kreuk Files PDF 1_s2.0_S0043135420304619_main.pdf 3.27 MB Close viewer /islandora/object/uuid:9b9e7380-d565-4e91-b9f2-09be77d45415/datastream/OBJ/view