Print Email Facebook Twitter On the mechanisms for aerobic granulation - model based evaluation Title On the mechanisms for aerobic granulation - model based evaluation Author van Dijk, E.J.H. (TU Delft BT/Environmental Biotechnology; Royal HaskoningDHV) Haaksman, V.A. (TU Delft BT/Environmental Biotechnology) van Loosdrecht, Mark C.M. (TU Delft BT/Environmental Biotechnology) Pronk, M. (TU Delft BT/Environmental Biotechnology; Royal HaskoningDHV) Date 2022 Abstract In this study a mathematical framework was developed to describe aerobic granulation based on 6 main mechanisms: microbial selection, selective wasting, maximizing transport of substrate into the biofilm, selective feeding, substrate type and breakage. A numerical model was developed using four main components; a 1D convection/dispersion model to describe the flow dynamics in a reactor, a reaction/diffusion model describing the essential conversions for granule growth, a setting model to track granules during settling and feeding, and a population model containing up to 100,000 clusters of granules to model the stochastic behaviour of the granulation process. With this approach the model can explain the dynamics of the granulation process observed in practice. This includes the presence of a lag phase and a granulation phase. Selective feeding was identified as an important mechanism that was not yet reported in literature. When aerobic granules are grown from activated sludge flocs, a lag phase occurs, in which not many granules are formed, followed by a granulation phase in which granules rapidly appear. The ratio of granule forming to non-granule forming substrate together with the feast/famine ratio determine if the transition from the lag phase to the granulation phase is successful. The efficiency of selective wasting and selective feeding both determine the rate of this transition. Brake-up of large granules into smaller well settling particles was shown to be an important source for new granules. The granulation process was found to be the combined result from all 6 mechanisms and if conditions for either one are not optimal, other mechanisms can, to some extent, compensate. This model provides a theoretical framework to analyse the different relevant mechanisms for aerobic granular sludge formation and can form the basis for a comprehensive model that includes detailed nutrient removal aspects. Subject Aerobic granular sludgeGranule formationKey parametersModellingSensitivity analysesSimulation To reference this document use: http://resolver.tudelft.nl/uuid:e74dea6a-1124-43df-bdfb-5a2f67f0a18c DOI https://doi.org/10.1016/j.watres.2022.118365 ISSN 0043-1354 Source Water Research, 216 Part of collection Institutional Repository Document type journal article Rights © 2022 E.J.H. van Dijk, V.A. Haaksman, Mark C.M. van Loosdrecht, M. Pronk Files PDF 1_s2.0_S004313542200327X_main.pdf 3.58 MB Close viewer /islandora/object/uuid:e74dea6a-1124-43df-bdfb-5a2f67f0a18c/datastream/OBJ/view