Influence of light intensity on bacterial nitrifying activity in algal-bacterial photobioreactors and its implications for microalgae-based wastewater treatment. (October 2016)

• Record Type: Journal Article
• Authors: Vergara, C.; Muñoz, R.; Campos, J.L.; Seeger, M.; Jeison, D.
• Is Part Of: International biodeterioration & biodegradation. Volume 114(2016)
• Page Start: 116
• Page End: 121
• Publication Date: 2016-10
• Subjects: Nitrification -- Ammonium oxidizer -- Nitrite oxidizer -- Microalgal-bacterial consortium -- Photobioreactor -- Photoinhibition -- Wastewater treatment; Biodegradation -- Periodicals; Bioremediation -- Periodicals; Biodegradation -- Periodicals; Biodégradation -- Périodiques; Biorestauration -- Périodiques; Electronic journals; 620.11223
• DOI: 10.1016/j.ibiod.2016.06.006
• Languages: English
• ISSNs: 0964-8305

Abstract

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 m 2 g −1 ) and of Chlorella sorokiniana (λ = 0.1045 m 2 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. Highlights: Light irradiation over 500 μmol/m 2 s reduces bacterial nitrifying activity. Nitrite oxidizers are more light-sensitive than ammonia oxidizers. Light attenuation by microalgae may prevent nitrification photoinhibition.