Determination of the external mass transfer coefficient and influence of mixing intensity in moving bed biofilm reactors for wastewater treatment

Nogueira, Bruno L.; Pérez, Julio; Loosdrecht, M.C.M. van; Secchi, Argimiro Resende; Dezotti, Márcia; Biscaia, Evaristo C.

doi:10.1016/j.watres.2015.05.010

Cited by 30 publications

(8 citation statements)

References 23 publications

(23 reference statements)

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“…The amount of ammonia nitrogen converted by Kaldnes K1 was not greater than the amount of ammonia nitrogen converted by the medium or small SSA gyroids, even though the SSA of the Kaldnes K1 (1519 m 2 /m 3 ) is nominally larger than the other two (1013 and 524 m 2 /m 3 respectively). However, the amount of ammonia nitrogen converted by the Kaldnes K1 biocarrier was consistent with its reported surface area of 500 m 2 /m 3 as communicated by the manufacturer [ 40 , 41 ]. This suggests that the performance of the gyroid media is enhanced beyond the subsidy of greater SSA, with this enhancement coming from materials considerations or particular characteristics of the gyroid shape.…”

Section: Resultssupporting

confidence: 82%

“…It is important to highlight the performance of medium SSA gyroids, where almost 100% of ammonia nitrogen was converted within 8 hours, approaching the same conversion rate as the high SSA gyroids in Experiment 1 (0.40 mg/L/hour), even though the number of biocarriers was decreased (25 to 13) in these trials. A potential reason for this continued high performance is that, under the conditions in Experiment 2, the decrease in the number of biocarriers in the reactor allowed for increased agitation and increased mixing intensities, enhancing mass transfer of oxygen or substrate [ 40 , 41 ]. Additionally, the high performance of the medium SSA gyroid, compared to others, suggests that an optimum configuration of surface area exists, given that the total surface area in all trials is the same.…”

Section: Resultsmentioning

confidence: 99%

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Analysis of very-high surface area 3D-printed media in a moving bed biofilm reactor for wastewater treatment

2020

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Moving Bed Biofilm Reactors (MBBRs) can efficiently treat wastewater by incorporating suspended biocarriers that provide attachment surfaces for active microorganisms. The performance of MBBRs for wastewater treatment is, among other factors, contingent upon the characteristics of the surface area of the biocarriers. Thus, novel biocarrier topology designs can potentially increase MBBR performance in a significant manner. The goal of this work is to assess the performance of 3-D-printed biofilter media biocarriers with varying surface area designs for use in nitrifying MBBRs for wastewater treatment. Mathematical models, rendering, and 3D printing were used to design and fabricate gyroid-shaped biocarriers with a high degree of complexity at three different levels of specific surface area (SSA), generally providing greater specific surface areas than currently available commercial designs. The biocarriers were inoculated with a nitrifying bacteria community, and tested in a series of batch reactors for ammonia conversion to nitrate, in three different experimental configurations: constant fill ratio, constant total surface area, and constant biocarrier media count. Results showed that large and medium SSA gyroid biocarriers delivered the best ammonia conversion performance of all designs, and significantly better than that of a standard commercial design. The percentage of ammonia nitrogen conversion at 8 hours for the best performing biocarrier design was: 99.33% (large SSA gyroid, constant fill ratio), 94.74% (medium SSA gyroid, constant total surface area), and 92.73% (large SSA gyroid, constant biocarrier media count). Additionally, it is shown that the ammonia conversion performance was correlated to the specific surface area of the biocarrier, with the greatest rates of ammonia conversion (99.33%) and nitrate production (2.7 mg/L) for manufactured gyroid biocarriers with a specific surface area greater than 1980.5 m 2 /m 3 . The results suggest that the performance of commercial MBBRs for wastewater treatment can be greatly improved by manipulation of media design through topology optimization.

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Section: Resultssupporting

confidence: 82%

Section: Resultsmentioning

confidence: 99%

Analysis of very-high surface area 3D-printed media in a moving bed biofilm reactor for wastewater treatment

2020

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“…This layer of heterotrophs could have multiple negative effects. Firstly, the heterotrophic layer could act as an additional diffusion layer that increases the external mass transfer [45]. Secondly, the heterotrophic growth could consume so much oxygen that the AOB becomes oxygen limited.…”

Section: Impact Of Bodmentioning

confidence: 99%

Towards mainstream anammox: lessons learned from pilot-scale research at WWTP Dokhaven

Hoekstra

Geilvoet²,

Hendrickx

et al. 2018

Environmental Technology

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The aim of this research was to study the biological feasibility of the Partial Nitritation/Anammox (PN/A) technology to remove nitrogen from municipal mainstream wastewaters. During stable process operations at summer temperatures (23.2 ± 1.3°C), the total nitrogen removal rate was 0.223 ± 0.029 kg N (md) while at winter temperatures (13.4 ± 1.1°C) the total nitrogen removal rate was 0.097 ± 0.016 kg N (m d). Nitrite-oxidizing bacteria (NOB) suppression was successfully achieved at the complete temperature range of municipal mainstream wastewater. Despite the presence of NOB as observed in activity tests, their activity could be successfully suppressed due to a relative low dissolved oxygen concentration. An overcapacity of ammonia-oxidizing bacteria and anammox activity was always present. Long-term stability is a focus point for future research, especially in relation to the stability of the biological oxygen demand removing step, preceding the PN/A reactor.

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“…Many biofilm carriers have irregular geometries and assuming flat geometry can introduce a systematic error for thicker biofilms. The geometry of typical carriers might also lead to imperfect mixing and MTBLs within the carrier (Gapes & Keller, 2009; Nogueira et al, 2015; Tang et al, 2017). Even if the estimate of biofilm surface area would be more precise, this does not mean that the methods are more precise.…”

Section: Resultsmentioning

confidence: 99%

How to measure diffusion coefficients in biofilms: A critical analysis

Berg

Loosdrecht

Kreuk

2020

Biotech & Bioengineering

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Biofilm and granular sludge processes depend on diffusion of substrates. Despite their importance for the kinetic description of biofilm reactors, biofilm diffusion coefficients reported in literature vary greatly. The aim of this simulation study was to determine to what extent the methods that are used to measure diffusion coefficients contribute to the reported variability. Granular sludge was used as a case study. Six common methods were selected, based on mass balances and microelectrodes. A Monte Carlo simulation was carried out to determine the theoretical precision of each method, considering the uncertainty of various experimental parameters. A model‐based simulation of a diffusion experiment was used to determine the theoretical accuracy as a result of six sources of error: solute sorption, biomass deactivation, mass transfer boundary layer, granule roughness, granule shape, and granule size distribution. Based on the Monte Carlo analysis, the relative standard deviation of the different methods ranged from 5% to 61%. In a theoretical experiment, the six error sources led to an 37% underestimation of the diffusion coefficient. This highlights that diffusion coefficients cannot be determined accurately with existing experimental methods. At the same time, the need for measuring precise diffusion coefficients as input value for biofilm modeling can be questioned, since the output of biofilm models has a limited sensitivity toward the diffusion coefficient.

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Determination of the external mass transfer coefficient and influence of mixing intensity in moving bed biofilm reactors for wastewater treatment

Cited by 30 publications

References 23 publications

Analysis of very-high surface area 3D-printed media in a moving bed biofilm reactor for wastewater treatment

Analysis of very-high surface area 3D-printed media in a moving bed biofilm reactor for wastewater treatment

Towards mainstream anammox: lessons learned from pilot-scale research at WWTP Dokhaven

How to measure diffusion coefficients in biofilms: A critical analysis

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