Effects of light and mass ratio of microalgae and nitrifiers on the rates of ammonia oxidation and nitrate production

Kwon, Gyutae; Le, Linh-Thy; Jeon, Joeun; Noh, Jongchan; Jang, Youngho; Kang, Donghan; Jahng, Deokjin

doi:10.1016/j.bej.2020.107656

Cited by 22 publications

(8 citation statements)

References 78 publications

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“…Nitrification and denitrification rates measured in the present study generally fall within the published range of in situ measurements in tidal pools dominated by algae and corals (Webb and Wieber, 1975), in cavities covered in encrusting sponges (Scheffers et al, 2004), on cyanobacterial mats (Bonin and Michotey, 2006), and on carbonate sand (Capone et al, 1992;Eyre et al, 2013b). However, there was no nitrification during the day (except for one community dominated by sponges), which may be explained by light causing a reduced activity of nitrifiers (Kwon et al, 2020). Owing to the rather shallow depths of our experiment, nitrifiers may have been negatively affected by the light.…”

Section: Nitrogen Cyclingmentioning

confidence: 69%

Quantifying functional consequences of habitat degradation on a Caribbean coral reef

et al. 2021

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Abstract. Coral reefs are declining worldwide. The abundance of corals has decreased alongside a rise of filter feeders, turf, and algae in response to intensifying human pressures. This shift in prevalence of functional groups alters the biogeochemical processes in tropical water ecosystems, thereby influencing reef functioning. An urgent challenge is to understand the functional consequences of these shifts to develop suitable management strategies that aim at preserving the biological functions of reefs. Here, we quantify biogeochemical processes supporting key reef functions (i.e. net community calcification (NCC) and production (NCP) and nutrient recycling) in situ for five different benthic assemblages currently dominating shallow degraded Caribbean reef habitats. To this end, a transparent custom-made enclosure was placed over communities dominated by either one of five functional groups – coral, turf and macroalgae, bioeroding sponges, cyanobacterial mats, or sand – to determine chemical fluxes between these communities and the overlying water, during both day and night. To account for the simultaneous influence that distinct biogeochemical processes have on measured variables, the rates were then derived by solving a model consisting of differential equations describing the contribution of each process to the measured chemical fluxes. Inferred rates were low compared to those known for reef flats worldwide. Reduced accretion potential was recorded, with negative or very modest net community calcification rates for all communities. Net production during the day was also low, suggesting limited accumulation of biomass through photosynthesis and remineralisation of organic matter at night was relatively high in comparison, resulting in net heterotrophy over the survey period for most communities. Estimated recycling processes (i.e. nitrification and denitrification) were high but did not fully counterbalance nutrient release from aerobic mineralisation, rendering all substrates sources of nitrogen. Results suggest similar directions and magnitudes of key biogeochemical processes of distinct communities on this shallow Curaçaoan reef. We infer that the amount and type of organic matter released by abundant algal turfs and cyanobacterial mats on this reef likely enhances heterotroph activity and stimulates the proliferation of less diverse copiotrophic microbial populations, rendering the studied reef net heterotrophic and drawing the biogeochemical “behaviour” of distinct communities closer to each other.

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Section: Nitrogen Cyclingmentioning

confidence: 69%

Quantifying functional consequences of habitat degradation on a Caribbean coral reef

et al. 2021

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“…Vargas et al 59 . did not observe photoinhibition in a microalgal–nitrifier consortium under low light intensity (67.5 μmol m −2 s −1 ) or high biomass concentration (~4250 g TSS m −3 ); Kwon et al 22 . showed that the inhibitory effect of light on nitrifiers was partially reduced in co‐culture with microalgae under low light intensity (81 μmol m −2 s −1 ) and biomass concentrations from 1200 to 2800 g m −3 .…”

Section: Resultsmentioning

confidence: 97%

“…Several authors have reported the inhibition of the nitrifying community (responsible for oxidizing ammonium to nitrite and nitrate) caused by high light intensities. [21][22][23] Nitrification during periods with light is a key process in photosynthetic wastewater treatment since the formation of nitrate/nitrite allows the occurrence of denitrification during dark periods, boosting the organic matter and nutrient removal performance of the MAB systems. 24 Previous studies focused on photoinhibition of nitrifying activity in MAB systems were based on light intensity data taken outside the reactor (i.e., on the liquid surface, at the bottom of the photobioreactor under abiotic conditions, or back side opposite the light source).…”

Section: Introductionmentioning

confidence: 99%

Wastewater treatment potential, light penetration profile and biomass settling performance of a photo‐sequencing batch reactor

García

Valenzuela

Vargas

et al. 2022

J of Chemical Tech & Biotech

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BACKGROUND The performance of microalgal and bacterial systems devoted to wastewater treatment might be limited by the poor settling of microalgal biomass and the inhibition of nitrifying bacteria under high irradiance conditions. This work implemented a photo‐sequencing batch bioreactor (PSBR) treating medium‐ and low‐strength wastewaters. The impact of a short settling time on the formation of microalgal–bacterial aggregates (MABAs) was evaluated. Moreover, online photosynthetically active radiation (PAR) measurements at the bottom of the PSBR were used to identify potential nitrifying activity inhibition. RESULTS A chemical oxygen demand removal efficiency of up to 88% was obtained for the medium‐ and low‐strength wastewaters. Photoinhibition of the nitrifying activity was observed at PAR values from 73 to 480 μmol m−2 s−1, and it was confirmed under non‐limiting dissolved oxygen conditions. The PSBR operating conditions, including a short settling time (30 min) and treatment of medium‐strength wastewater, favored the rapid formation of MABAs in only 19 days, with a biomass settling velocity (vs) of 0.74 m h−1. The microalgal genera Acutudesmus, Desmodesmus, and Chlorella were predominant in the MABAs. Experimental estimation of the light extinction coefficient (λ = 0.056 m2 g−1 total suspended solids) allowed the simulation of light penetration profiles at different reactor liquid depths and biomass concentrations. CONCLUSION A short settling time favors the rapid formation of MABAs in PSBR‐type reactors treating medium‐strength wastewater. Online monitoring and simulation of light penetration is a valuable tool to determine photoinhibition of the nitrifying activity in microalgal and bacterial systems. © 2022 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

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“…Moreover, due to the light-induced nitrite accumulation observed in this study, the denitritation–microalgae system offers an alternative to energy-efficient nitrogen removal pathway in addition to the nitritation–microalgae system . However, attentions should be paid to the alleviation of the enhanced N 2 O emissions in denitrification under light irradiation, possibly using the self-shielding effect caused by microalgal biomass increase for photoprotection . Moreover, the sludge settleability needs to be improved for the flocs MBC system, including but not limited to establishment and stability maintenance of granular and/or biofilm MBC systems.…”

Section: Discussionmentioning

confidence: 99%

Effects of Light Energy with Different Densities on Denitrification: Metabolic Intermediates, Electron Behavior, Enzyme Activities, and Sludge Settleability

et al. 2023

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Light energy, as one of the most influencing parameters in microalgal−bacterial consortium (MBC) systems, can regulate activities and metabolisms of microalgae and bacteria consortia. However, its effects on denitrifying bacterial remain unclear. Herein, variations of denitrification, microbial (denitrifiers') metabolism, sludge surface characteristics, and settleability were systematically investigated with five light energy density conditions. Results showed that light energy decreased the denitrification rate with obvious accumulation of denitrifying intermediates (NO 2 − and N 2 O). This could be associated with the inhibition of light energy on electron behavior, evidenced from reduced nicotinamide adenine dinucleotide (by 67.0−71.3%), lowered electron transport system activity (by 66.7%), decreased denitrifying enzyme activities (e.g., NAR, NIR, and NOS), and downregulated gene expressions. Moreover, light energy worsened sludge settleability by regulating sludge extracellular polymeric substance (EPS) types, compositions, and surface characteristics. Specifically, light energy stimulated the soluble and lightly bounded EPS, as well as the hydrophilic and electronegative functional groups in EPS. These findings advance our understandings on denitrifiers activities and their electronic behavior responses to short-term light energy. Ultimately, this may promote the development of MBC as a sustainable approach for wastewater treatment.

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Effects of light and mass ratio of microalgae and nitrifiers on the rates of ammonia oxidation and nitrate production

Cited by 22 publications

References 78 publications

Quantifying functional consequences of habitat degradation on a Caribbean coral reef

Quantifying functional consequences of habitat degradation on a Caribbean coral reef

Wastewater treatment potential, light penetration profile and biomass settling performance of a photo‐sequencing batch reactor

Effects of Light Energy with Different Densities on Denitrification: Metabolic Intermediates, Electron Behavior, Enzyme Activities, and Sludge Settleability

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