Assessing the effects of intra-granule precipitation in a full-scale industrial anaerobic digester

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In this paper, a multi-scale model is used to assess the multiple mineral precipitation potential in a full-scale anaerobic granular sludge system. Reactor behaviour is analysed under different operational conditions (addition/no addition of reject water from dewatering of lime-stabilized biomass) and periods of time (short/long term). Model predictions suggest that a higher contribution of reject water promotes the risk of intra-granule CaCO3 formation as a result of the increased quantity of calcium arriving with that stream combined with strong pH gradients within the biofilm. The distribution of these precipitates depends on: (i) reactor height; and (ii) granule size. The study also exposes the potential undesirable effects of the long-term addition of reject water (a decrease in energy recovery of 20% over a 100-day period), caused by loss in biomass activity (due to microbial displacement), and the reduced buffer capacity. This demonstrates how both short-term and long-term operational conditions may affect the formation of precipitates within anaerobic granules, and how it may influence methane production and consequently energy recovery.


  • H. Feldman
  • X. Flores-Alsina
  • P. Ramin
  • K. Kjellberg
  • U. Jeppsson
  • D. J. Batstone
  • K. V. Gernaey
Enheter & grupper
Externa organisationer
  • Technical University of Denmark
  • Novozymes A/S
  • University of Queensland

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Vattenbehandling


Sidor (från-till)1327-1337
Antal sidor11
TidskriftWater Science and Technology
StatusPublished - 2019 apr 1
Peer review utfördJa