Tracking the dynamics of heterotrophs and nitrifiers in moving-bed biofilm reactors operated at different COD/N ratios

Bassin, João Paulo; Abbas, Ben; Vilela, Caren L. S.; Kleerebezem, Robbert; Muyzer, Gerard; Rosado, Alexandre Soares; Loosdrecht, M.C.M. van; Dezotti, Márcia

doi:10.1016/j.biortech.2015.05.051

Cited by 44 publications

(27 citation statements)

References 28 publications

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“…Nitrobacter were also identified as the dominant NOB at low C/N ratios (0-2.3) in a previous study 16 . However, other studies did not detect Nitrobacter in autotrophic biofilms 13,20,40 , suggesting that the initial microbial community composition may influence the steady-state community 55,56 . By contrast, Nitrospira was the dominant nitrifier in R1, present at a relative abundance as high as 20%.…”

Section: Discussionmentioning

confidence: 92%

“…In a given system, the inter-guild interaction between heterotrophs and nitrifiers may be dominantly mutualistic or competitive depending on several factors. These factors include oxygen and space availability [9][10][11] , specific loading rate of degradable carbon 12,13 , biofilm structure 14 , and organic carbon: ammonia nitrogen (C/N) ratio 7,15 .…”

mentioning

confidence: 99%

“…The response of nitrifying bioreactors to acute and chronic increases in carbon supply is poorly understood, especially in terms of the biofilm functionality and the microbial community composition. Most studies have investigated either short-term or long-term effects of the C/N ratio, but not both 4,7,13,19,20 . Therefore, we compared the impact of acute and chronic increases in organic carbon supply on two nitrifying moving bed biofilm reactors (MBBR).…”

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confidence: 99%

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Nitrifying biofilms deprived of organic carbon show higher functional resilience to increases in carbon supply

Navada

Knutsen

Bakke

et al. 2020

Sci Rep

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In nitrifying biofilms, the organic carbon to ammonia nitrogen (C/N) supply ratio can influence resource competition between heterotrophic and nitrifying bacteria for oxygen and space. We investigated the impact of acute and chronic changes in carbon supply on inter-guild competition in two moving bed biofilm reactors (MBBR), operated with (R1) and without (R0) external organic carbon supply. The microbial and nitrifying community composition of the reactors differed significantly. Interestingly, acute increases in the dissolved organic carbon inhibited nitrification in R1 ten times more than in R0. A sustained increase in the carbon supply decreased nitrification efficiency and increased denitrification activity to a greater extent in R1, and also increased the proportion of potential denitrifiers in both bioreactors. The findings suggest that autotrophic biofilms subjected to increases in carbon supply show higher nitrification and lower denitrification activity than carbon-fed biofilms. This has significant implications for the design of nitrifying bioreactors. Specifically, efficient removal of organic matter before the nitrification unit can improve the robustness of the bioreactor to varying influent quality. Thus, maintaining a low C/N ratio is important in nitrifying biofilters when acute carbon stress is expected or when anoxic activity (e.g. denitrification or H 2 S production) is undesirable, such as in recirculating aquaculture systems (RAS).

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Section: Discussionmentioning

confidence: 92%

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confidence: 99%

mentioning

confidence: 99%

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Nitrifying biofilms deprived of organic carbon show higher functional resilience to increases in carbon supply

Navada

Knutsen

Bakke

et al. 2020

Sci Rep

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“…Nitrification is generally considered to be autotrophic conversion of ammonia through nitrite to nitrate and is a key process in biological nitrogen removal. Because of the low growth rate of the organisms involved, it is commonly considered to be the overall rate-limiting step of the biological wastewater treatment process (Bassin et al, 2012). Nitrogen removal is catalyzed by specialized nitrifying chemolithoautotrophic prokaryotes and uses a two-step process to oxidize ammonia.…”

Section: Introductionmentioning

confidence: 99%

The Role of Microorganisms in a Full‐Scale Sequencing Batch Reactor Under Low Aeration and Different Cycle Times

Fernandes¹,

Hoffmann²,

Antônio

et al. 2014

Water Environment Research

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This study describes the role of microorganisms in a fullscale step-feed sequencing batch reactor (SBR) system for urban wastewater treatment. Chemical profiles for three different cycle times were measured under low aeration conditions with a high carbon-tonitrogen ratio. The applied organic load was above 1.0 g chemical oxygen demand (COD)/LÁd. The removal efficiencies were higher than 81%, 93%, and 76% for soluble COD, N-NH þ 4 , and total Kjeldahl nitrogen, respectively. The ratio of volatile suspended solids (VSS) to total suspended solids was 78%, and the food-to-microorganism ratio was an average of 1.41 g COD/g VSSÁd. The active biomass was comprised of 87.8% heterotrophic and 12.2% autotrophic organisms. Nitrifying organisms were found with a low amount of ammonia-oxidizing bacteria (5%) and a much higher amount of nitrite-oxidizing bacteria. Polyphosphate-accumulating organisms (PAOs) were found at high amounts (25%) compared to glycogen-accumulating organisms, even in a system with a high carbon to phosphorus ratio. The activity of denitrifying PAOs was 72%. Water Environ. Res., 86, 800 (2014).

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“…Figure depicts an inverse correlation of the C/N ratio with nitrification and denitrification rates, with a determination coefficient ( R 2 ) lower for the nitrification (0.856) than for the denitrification rate (0.987). High COD loads favor the development of heterotrophs, presenting higher growth rates and biomass yields than autotrophic nitrifiers .…”

Section: Resultsmentioning

confidence: 99%

Operational and Environmental Conditions for Efficient Biological Nutrient Removal in an Urban Wastewater Treatment Plant

Bayo

López-Castellanos²,

Puerta³

2016

CLEAN Soil Air Water

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This paper examines correlations and processes related to nutrient removal in a wastewater treatment plant (WWTP), verifying the efficiency of plant improvements and the extent that public awareness campaigns have had on treated water quality. Increases in water pH value resulted in a decrease in nitrate nitrogen and phosphate phosphorus levels in treated wastewater, demonstrating a better performance of microorganisms with higher pH values. On the contrary, both nutrients proved to increase with increasing temperatures, although there were no significant differences in the nitrogen loading rate, representing a good behavior of the WWTP despite the considered season. This fact can be explained by a new storm tank located at the sewage plant that cushions sharp-point organic loads, allowing a more stable performance of the WWTP. An increase in electrical conductivity resulted in higher phosphate phosphorus levels in the effluent, indicating a special sensitivity of phosphorus accumulating organisms (PAOs) to high osmotic pressures. High C/N ratios, both chemical oxygen demand and biochemical oxygen demand resulted in lower nitrification rates, indicating the favored growth of heterotrophs over slow-growing nitrifying bacteria. Sludge age proved to have a strong effect on nutrients removal, increasing the diversity of ammonia oxidizing bacteria but worsening the nitrogen removal efficiency with older solids residence time. In order to meet the requirements of the Council Directive (91/271/CEE) for phosphate phosphorus removal, an anaerobic selector for PAOs growing should be implemented.

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Tracking the dynamics of heterotrophs and nitrifiers in moving-bed biofilm reactors operated at different COD/N ratios

Cited by 44 publications

References 28 publications

Nitrifying biofilms deprived of organic carbon show higher functional resilience to increases in carbon supply

Nitrifying biofilms deprived of organic carbon show higher functional resilience to increases in carbon supply

The Role of Microorganisms in a Full‐Scale Sequencing Batch Reactor Under Low Aeration and Different Cycle Times

Operational and Environmental Conditions for Efficient Biological Nutrient Removal in an Urban Wastewater Treatment Plant

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