Abstract
The influence of irradiance on the nitrifying activity in photobioreactors of a bacterial consortium enriched from a wastewater treatment bioreactor was assessed using independent ammonium oxidation kinetic batch tests and respirometric assays. Culture irradiance below 250 μmol m-2 s-1 did not show a significant effect on nitrification activity, while irradiance at 500 and 1250 μmol m-2 s-1 caused a decrease of 20 and 60% in the specific total ammonium nitrogen removal rates and a reduction of 26 and 71% in the specific NO3- production rates, respectively. However, no significant influence of irradiance on the affinity constant of NH4+ oxidation was observed. The increasing nitrite accumulation at higher light intensities suggested a higher light sensitivity of nitrite oxidizers. Additionally, NH4+ oxidation respirometric assays showed a decrease in the oxygen uptake of 14 and 50% at 500 and 1250 μmol m-2 s-1, respectively. The experimental determination of the light extinction coefficient (λ) of the nitrifying bacterial consortium (λ = 0.0003 m2 g-1) and of Chlorella sorokiniana (λ = 0.1045 m2 g-1) allowed the estimation of light penetration in algal-bacterial high rate algal ponds, which showed that photoinhibition of nitrifying bacteria can be significantly mitigated in the presence of high density microalgal cultures.
Original language | English |
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Pages (from-to) | 116-121 |
Number of pages | 6 |
Journal | International Biodeterioration and Biodegradation |
Volume | 114 |
DOIs | |
State | Published - 1 Oct 2016 |
Externally published | Yes |
Keywords
- Ammonium oxidizer
- Microalgal-bacterial consortium
- Nitrification
- Nitrite oxidizer
- Photobioreactor
- Photoinhibition
- Wastewater treatment