Abstract
Membrane photobioreactors (MPBR) have the opportunity to remove various forms of nitrogen, such as ammonium and nitrate, found in high quantities in secondary effluent. This study provides a holistic comparison of the performance of two membrane photobioreactors treating secondary effluents containing ammonium (NH4+-N) or nitrate (NO3−-N) as the sole nitrogen source. Sophisticated analyses, such as flow cytometry, polymerase chain reaction denaturing gradient gel electrophoresis, liquid chromatography – organic carbon detection analysis and fluorescence excitation-emission matrix spectroscopy, were used to provide insight into system characteristics and performance. In terms of treatment efficiency, NH4+-N was better removed from the system (by 56%) compared to NO3−-N (33%). The MPBR fed with NH4+-N produced less microalgal cells (4.4 × 107 cells/ml compared to 5.3 × 107 cells/ml in that treating NO3−-N) but higher proportion of bacteria (6.3% compared to 2.1%), leading to a higher system heterogeneity. The biomass produced from the MPBR treating NH4+-N featured a higher level of extracellular materials and a lower dewaterability (as suggested by a significantly higher capillary suction time of 25.2 s than 13.1 s observed for the culture grown on NO3−-N), indicating a lower harvesting potential. As a result, faster membrane fouling was observed when NH4+-N was fed. This leads to a recommendation that operating conditions are optimised dependent on the form of nitrogen that needs to be treated.
Original language | English |
---|---|
Article number | 102013 |
Pages (from-to) | 1-9 |
Number of pages | 9 |
Journal | Algal Research |
Volume | 50 |
Early online date | 22 Jul 2020 |
DOIs | |
Publication status | Published - Sept 2020 |
Externally published | Yes |
Keywords
- Nutrient removal
- Secondary effluent
- Microbial community
- Organic characterisation
- Membrane fouling