Aggregation of purple bacteria in an upflow photobioreactor to facilitate solid/liquid separation: Impact of organic loading rate, hydraulic retention time and water composition

Naïm Blansaer, Abbas Alloul, Willy Verstraete, Siegfried E. Vlaeminck*, Barth F. Smets

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Purple non-sulfur bacteria (PNSB) form an interesting group of microbes for resource recovery from wastewater. Solid/liquid separation is key for biomass and value-added products recovery, yet insights into PNSB aggregation are thus far limited. This study explored the effects of organic loading rate (OLR), hydraulic retention time (HRT) and water composition on the aggregation of Rhodobacter capsulatus in an anaerobic upflow photobioreactor. Between 2.0-14.6 gCOD/(L.d), the optimal OLR for aggregation was 6.1 gCOD/(L.d), resulting in a sedimentation flux of 5.9 kgTSS/(m2.h). For HRT tested between 0.04-1.00 d, disaggregation occurred at the relatively long HRT (1 d), possibly due to accumulation of thus far unidentified heat-labile metabolites. Chemical oxygen demand (COD) to nitrogen (6-35 gCOD/gN) and the nitrogen source (ammonium vs. glutamate) also impacted aggregation, highlighting the importance of the specific wastewater type and its pre-treatment. These novel insights to improve purple biomass separation pave the way for cost-efficient PNSB applications.
Original languageEnglish
Article number126806
JournalBioresource Technology
Volume348
Number of pages9
ISSN0960-8524
DOIs
Publication statusPublished - 2022

Keywords

  • Nutrient recovery
  • Purple phototrophic bacteria
  • Granular sludge
  • Flocculation
  • Granulation

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