Multipopulation Model of Membrane-Aerated Biofilms

Shanahan, John W.; Semmens, Michael J.

doi:10.1021/es034809y

Cited by 57 publications

(39 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Such high J O 2 are attained by high oxygen concentrations or pressure in the gas compartment, resulting in elevated oxygen concentration at the biofilm base: under such conditions, the activity of AeNOB cannot be hindered, resulting in nitrite oxidation, which depletes the electron acceptor for AnAOB, and finally results in performance deterioration. A similar prediction was made by Shanahan and Semmens (2004), who observed deterioration of the traditional nitrification/denitrification by membrane-aerated biofilm, under excess oxygen loading. In conclusion, the counterdiffusion biofilm displays a wider operational range for autotrophic nitrogen removal than the co-diffusion biofilm.…”

Section: Effect Of Biofilm Thickness On Performance At Fixed Loadingssupporting

confidence: 81%

Redox‐stratification controlled biofilm (ReSCoBi) for completely autotrophic nitrogen removal: The effect of co‐ versus counter‐diffusion on reactor performance

Terada

Lackner

Tsuneda

et al. 2006

Biotech & Bioengineering

View full text Add to dashboard Cite

A multi-population biofilm model for completely autotrophic nitrogen removal was developed and implemented in the simulation program AQUASIM to corroborate the concept of a redox-stratification controlled biofilm (ReSCoBi). The model considers both counter- and co-diffusion biofilm geometries. In the counter-diffusion biofilm, oxygen is supplied through a gas-permeable membrane that supports the biofilm while ammonia (NH(4)(+)) is supplied from the bulk liquid. On the contrary, in the co-diffusion biofilm, both oxygen and NH(4)(+) are supplied from the bulk liquid. Results of the model revealed a clear stratification of microbial activities in both of the biofilms, the resulting chemical profiles, and the obvious effect of the relative surface loadings of oxygen and NH(4)(+) (J(O(2))/J(NH(4)(+))) on the reactor performances. Steady-state biofilm thickness had a significant but different effect on T-N removal for co- and counter-diffusion biofilms: the removal efficiency in the counter-diffusion biofilm geometry was superior to that in the co-diffusion counterpart, within the range of 450-1,400 microm; however, the efficiency deteriorated with a further increase in biofilm thickness, probably because of diffusion limitation of NH(4)(+). Under conditions of oxygen excess (J(O(2))/J(NH(4)(+)) > 3.98), almost all NH(4)(+) was consumed by aerobic ammonia oxidation in the co-diffusion biofilm, leading to poor performance, while in the counter-diffusion biofilm, T-N removal efficiency was maintained because of the physical location of anaerobic ammonium oxidizers near the bulk liquid. These results clearly reveal that counter-diffusion biofilms have a wider application range for autotrophic T-N removal than co-diffusion biofilms.

show abstract

Section: Effect Of Biofilm Thickness On Performance At Fixed Loadingssupporting

confidence: 81%

Redox‐stratification controlled biofilm (ReSCoBi) for completely autotrophic nitrogen removal: The effect of co‐ versus counter‐diffusion on reactor performance

Terada

Lackner

Tsuneda

et al. 2006

Biotech & Bioengineering

View full text Add to dashboard Cite

show abstract

“…The fact that age did not affect biofilm cohesion in our study is not surprising, as results of aging are most likely accounted for by changes in polysaccharide concentration. In this study, we investigated a membrane-aerated biofilm in which counter- gradients of oxygen and substrate exist (29,30). Membraneaerated biofilms are complex, with regions within the biofilm that are highly oxic and have low substrate concentrations, regions with high substrate concentrations but no DO, and conditions in between.…”

Section: Discussionmentioning

confidence: 99%

Effect of Protein, Polysaccharide, and Oxygen Concentration Profiles on Biofilm Cohesiveness

Ahimou¹,

Semmens²,

Haugstad

et al. 2007

Appl Environ Microbiol

Self Cite

167

View full text Add to dashboard Cite

It is important to control biofilm cohesiveness to optimize process performance. In this study, a membraneaerated biofilm reactor inoculated with activated sludge was used to grow mixed-culture biofilms of different ages and thicknesses. The cohesions, or cohesive energy levels per unit volume of biofilm, based on a reproducible method using atomic force microscopy (F. Ahimou, M. J. Semmens, P. J. Novak, and G. Haugstad, Appl. Environ. Microbiol. 73:2897-2904, 2007), were determined at different locations within the depths of the biofilms. In addition, the protein and polysaccharide concentrations within the biofilm depths, as well as the dissolved oxygen (DO) concentration profiles within the biofilms, were measured. It was found that biofilm cohesion increased with depth but not with age. Level of biofilm cohesive energy per unit volume was strongly correlated with biofilm polysaccharide concentration, which increased with depth in the membrane-aerated biofilm. In a 12-day-old biofilm, DO also increased with depth and may therefore be linked to polysaccharide production. In contrast, protein concentration was relatively constant within the biofilm and did not appear to influence cohesion.Biofilms are ubiquitous in nature, and they can be beneficial or troublesome, depending upon where and how they grow. There appears to be a consensus that the content of extracellular polymeric substances (EPS) is important in biofilm cohesion and biofilm adhesion to surfaces. For example, Klapper et al. (17) used a model based on polymer viscoelastic properties and suggested that the material properties of biofilm were largely determined by the EPS, implying that biofilm strength should indeed be linked to EPS quantity and composition. In addition, a recent study by Xavier et al. (35) proposed a kinetic model to describe biofilm detachment that was based on enzymatic disruption of the EPS matrix, thereby affecting biofilm cohesiveness.The EPS content of a biofilm can differ in quantity and character as a result of environmental factors. Numerous environmental factors have been reported to promote EPS production. These include high levels of oxygen (4), limited availability of nitrogen (15,22), desiccation (25), low temperature (16), low pH (28), and nutrient deprivation (20). Weiner et al. (34) described several roles and functions for EPS, including that of protection against environmental stress. In addition, Davies et al. (8) showed that activation of a gene (algC) for production of the exopolymer alginate was higher for Pseudomonas aeruginosa when attached to a Teflon mesh than for unattached P. aeruginosa. This suggests that organisms are able to respond to their environments and change EPS compositions and therefore their adhesion abilities, based on the surfaces to which they attach. Multivalent cations, such as those of calcium and magnesium, also probably play a role in the cohesiveness of microbial aggregates, as evaluated from studies of anaerobic sludge granules (12), activated sludge flocs (13), and biofilms ...

show abstract

“…A number of models have been presented in order to aid the understanding the unique nutrient profiles which occur in the MABR, for example (Casey et al, 1999;Essila et al, 2000;Wanner et al, 1994). Multispecies 1-dimensional modeling has also been examined by Shanahan and Semmens (2004) and Terada et al (2007). A recent development has been the application of spatially structured biofilm modeling to the MABR (Matsumoto et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

Model‐based comparative performance analysis of membrane aerated biofilm reactor configurations

Syron

Casey

2007

Biotech & Bioengineering

View full text Add to dashboard Cite

The potential of the membrane aerated biofilm reactor (MABR) for high-rate bio-oxidation was investigated. A reaction-diffusion model was combined with a preliminary hollow-fiber MABR process model to investigate reaction rate-limiting regime and to perform comparative analysis on prospective designs and operational parameters. High oxidation fluxes can be attained in the MABR if the intra-membrane oxygen pressure is sufficiently high, however the volumetric oxidation rate is highly dependent on the membrane specific surface area and therefore the maximum performance, in volumetric terms, was achieved in MABRs with relatively thin fibers. The results show that unless the carbon substrate concentration is particularly high, there does not appear to be an advantage to be gained by designing MABRs on the basis of thick biofilms even if oxygen limitations can be overcome.

show abstract

Multipopulation Model of Membrane-Aerated Biofilms

Cited by 57 publications

References 21 publications

Redox‐stratification controlled biofilm (ReSCoBi) for completely autotrophic nitrogen removal: The effect of co‐ versus counter‐diffusion on reactor performance

Redox‐stratification controlled biofilm (ReSCoBi) for completely autotrophic nitrogen removal: The effect of co‐ versus counter‐diffusion on reactor performance

Effect of Protein, Polysaccharide, and Oxygen Concentration Profiles on Biofilm Cohesiveness

Model‐based comparative performance analysis of membrane aerated biofilm reactor configurations

Contact Info

Product

Resources

About