Combined nitrification/denitrification in a membrane reactor

Walter, Bert; Haase, Cornelia; Räbiger, Norbert

doi:10.1016/j.watres.2005.04.027

Cited by 36 publications

(22 citation statements)

References 3 publications

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“…The composition of the substrate (e.g., the carbon concentration expressed by the C:N ratio) has a considerable influence on the nitrification (Walter et al 2005;Seixo et al 2004).…”

Section: The Numerical Frameworkmentioning

confidence: 99%

“…In combination with high volumetric loading rates, high C:N ratios lead to a noticeable decrease in the nitrification rate. Therefore, the competition for the available oxygen shifts the balance within the biofilm, favouring the denitrifying bacteria (Walter et al 2005); this result should be considered also when evaluating the recirculation ratio.…”

Section: Cod Inlet Variationmentioning

confidence: 99%

“…In recent years, many of these technologies have been tested and applied, mainly for the industrial wastewater, to pilot and full-scale plants. The importance of developing new technologies also in the civil field is linked to the high space requirements of conventional treatment plants (mainly activated sludge systems) and to the related high impacts on populations in terms of noise and odours production (Walter et al 2005). Airlift technology reactors represent a potential solution, where the high oxygen levels in the stream assure both high efficiencies and low odour impact.…”

Section: Introductionmentioning

confidence: 99%

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A wastewater treatment using a biofilm airlift suspension reactor with biomass attached to supports: a numerical model

Viotti

Luciano

Mancini

et al. 2013

Int. J. Environ. Sci. Technol.

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A mathematical model of the biological process occurring in a modified biofilm airlift suspension reactor is presented. When compared with a traditional wastewater treatment plant, a biofilm airlift suspension process has major advantages, such as higher oxygen levels in the bulk fluid and lower space requirements. The limited volumes obtained with this technique generally do not allow to reach the high times of contact required for an efficient removal of nitrogen that normally are characterized by a slower kinetics than carbonaceous compounds. To avoid this problem, supports for attached biomass growth were inserted in the reactor. Both physical and biological aspects were incorporated into the presented model to simulate the removal processes of the substrates. A sensitivity analysis was performed, and the model was validated using experimental results obtained at a lab-scale plant. This model can accurately estimate the removal rate in different boundary conditions providing the details of the water quality profiles through the reactor and in the attached biomass. The model thus represents a valid aid for design purposes and for the management of treatment plants that use these uncommon reactors. The model also provides the required hydraulic retention time for a complete nitrification and the appropriate recirculation ratio. The results have shown the full-scale applicability of this treatment due to its efficiencies coupled to the advantages of its low impact, low space requirement and low sludge production.

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“…The composition of the substrate (e.g., the carbon concentration expressed by the C:N ratio) has a considerable influence on the nitrification (Walter et al 2005;Seixo et al 2004).…”

Section: The Numerical Frameworkmentioning

confidence: 99%

Section: Cod Inlet Variationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A wastewater treatment using a biofilm airlift suspension reactor with biomass attached to supports: a numerical model

Viotti

Luciano

Mancini

et al. 2013

Int. J. Environ. Sci. Technol.

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“…Esto sería indicativo de un incremento del espesor y/o concentración de la biopelícula nitrificante lo cual implicaría un aumento en la resistencia al transporte. Esto estaría en la línea de lo que señalaban otros autores ya citados, que la mejora en la transferencia de oxígeno debido a la biopelícula dependería entre otros factores de las características de la propia biopelícula (Suzuki et al, 1993;Osa et al, 1997;Brindle et al, 1998;Walter et al, 2005;Shanahan et al, 2006;Hu et al, 2008). Finalmente, la ventilación fue continua, de modo que podría estudiarse la viabilidad de realizar una aireación intermitente con el objetivo de reducir el consumo energético.…”

Section: Puesta En Marcha Del Reactor En Estado Transitoriounclassified

“…Los autores mencionados coinciden en señalar que la mejora de la transferencia de oxígeno a través de una membrana debido al desarrollo de una biopelícula es un fenómeno irregular afectado por la hidráulica del proceso y las características de la biopelícula como su espesor o concentración, señalando que cuando la acumulación de biopelícula llega a ser excesiva se produciría una pérdida de eficiencia en la transferencia de oxígeno. Según Walter et al (2005) en biopelículas de nitrificación -desnitrificación el espesor de la capa nitrificante puede llegar a 400-600 µm.…”

Section: Introductionunclassified

Nitrificación en reactores biopelícula de membrana tubular permeable a gases

et al. 2009

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Resumo: En este trabajo un reactor biopelícula de membrana tubular micro-porosa de polipropileno aireada ha sido desarrollado para la nitrificación de un agua residual sintética. El reactor ha sido explotado en régimen transitorio y sin presurizar las membranas. El proceso es viable sin presurizar las membranas debido a la auto-aireación de la biopelícula. Sin embargo, sino se renueva la atmósfera interna de las membranas, cuando se ha desarrollado la biopelícula, la nitrificación solo es parcial produciéndose una acumulación de nitrito. Los resultados muestran que la capacidad de aireación de las membranas limpias está condicionada por el espesor de la capa líquida de difusión adyacente a las membranas. Cuando la velocidad del fluido es nula, el coeficiente de transferencia de oxígeno, KL, tiene un valor medio de 0,27 m/d; siendo la correspondiente transferencia máxima de oxígeno de 2,39 g/m2/d y la nitrificación inherente de 0,53 g N/m2/d. La producción de fangos fue nula. Finalmente, el desarrollo de la biopelícula no produjo un incremento significativo en la transferencia de oxígeno a través de las membranas. INTRODUCCIÓNLos reactores biopelícula de membrana aireada permeable a gases ("MABR", siglas en inglés de Membrane Aerated Biofilm Reactor) han demostrado ser un proceso viable para la eliminación simultánea de materia orgánica y nitrógeno de las aguas residuales. Las configuraciones de las membranas utilizadas comprenden: membranas planas, membranas de fibra hueca y membranas tubulares. Las membranas pueden ser microporosas (de politetrafluoretileno, polipropileno, polivinilideno, etc.) y no porosas (generalmente de silicona).En los MABR la adherencia de las bacterias a la superficie de la membrana provoca la formación de una biopelícula. El oxígeno pasa a través de la pared de la membrana y es utilizado por las bacterias para oxidar los contaminantes que, a su vez, penetran la biopelícula desde el seno del agua residual. El oxígeno no utilizado por la biopelícula difunde hacia el seno líquido.En una biopelícula desarrollada sobre membrana permeable a gases pueden desarrollarse los ambientes requeridos, aerobio y anóxico, para la eliminación simultánea de materia orgánica y nitrógeno. Dependiendo de las fuentes disponibles de oxígeno se puede tener dos tipos de biopelícula en una membrana aireada: una con flujo uni-direccional de oxígeno a través de la membrana, en estos casos el agua es anóxica o se desoxigena (Timberlake et al., 1988;Eguía, 1991;Vidart et al., 1993;, y otra con flujo bi-direccional de oxígeno, a través de la membrana y desde el seno líquido (Jácome et al., 2006).En estudios precedentes con reactores biopelícula de membrana aireada en los que se realizó nitrificación/desnitrificación, la nitrificación fue perturbada por la demanda de oxígeno para la oxidación orgánica (Jácome, 1999). En general, por ser de más rápido crecimiento, las bacterias heterotrofas consumieron preferentemente el oxígeno disponible. Así, la nitrificación quedó a expensas de las "sobras" de oxígeno que dejaba la ...

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Effect of oxygen gradients on the activity and microbial community structure of a nitrifying, membrane‐aerated biofilm

Downing

Nerenberg

2008

Biotech & Bioengineering

116

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Shortcut nitrogen removal, that is, removal via formation and reduction of nitrite rather than nitrate, has been observed in membrane-aerated biofilms (MABs), but the extent, the controlling factors, and the kinetics of nitrite formation in MABs are poorly understood. We used a special MAB reactor to systematically study the effects of the dissolved oxygen (DO) concentration at the membrane surface, which is the biofilm base, on nitrification rates, extent of shortcut nitrification, and microbial community structure. The focus was on anoxic bulk liquids, which is typical in MAB used for total nitrogen (TN) removal, although aerobic bulk liquids were also studied. Nitrifying MABs were grown on a hollow-fiber membrane exposed to 3 mg N/L ammonium. The MAB intra-membrane air pressure was varied to achieve different DO concentrations at the biofilm base, and the bulk liquid was anoxic or with 2 g m(-3) DO. With 2.2 and 3.5 g m(-3) DO at the biofilm base, and with an anoxic bulk-liquid, the ammonium fluxes were 0.75 and 1.0 g N m(-2) day(-1), respectively, and nitrite was the main oxidized nitrogen product. However, with membrane DO of 5.5 g m(-3), and either zero or 2 g m(-3) DO in the bulk, the ammonium flux was around 1.3 g N m(-2) day(-1), and nitrate flux increased significantly. For all experiments, the cell density of ammonium oxidizing bacteria (AOB) was relatively uniform throughout the biofilm, but the density of nitrite oxidizing bacteria (NOB) decreased with decreasing biofilm DO. Among NOB, Nitrobacter spp. were dominant in biofilm regions with 2 g m(-3) DO or greater, while Nitrospira spp. were dominant in regions with less than 2 g m(-3) DO. A biofilm model, including AOB, Nitrobacter spp., and Nitrospira spp., was developed and calibrated with the experimental results. The model predicted the greatest extent of nitrite formation (95%) and the lowest ammonium oxidation flux (0.91 g N m(-2) day(-1)) when the membrane DO was 2 g m(-3) and the bulk liquid was anoxic. Conversely, the model predicted the lowest extent of nitrite formation (40%) and the highest ammonium oxidation flux (1.5 g N m(-2) day(-1)) when the membrane-DO and bulk-DO were 8 g m(-3) and 2 g m(-3), respectively. The estimated kinetic parameters for Nitrospira spp., revealed a high affinity for nitrite and oxygen. This explains the dominance of Nitrospira spp. over Nitrobacter spp. in regions with low nitrite and oxygen concentrations. Our results suggest that shortcut nitrification can effectively be controlled by manipulating the DO at the membrane surface. A tradeoff is made between increased nitrite accumulation at lower DO, and higher nitrification rates at higher DO.

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Combined nitrification/denitrification in a membrane reactor

Cited by 36 publications

References 3 publications

A wastewater treatment using a biofilm airlift suspension reactor with biomass attached to supports: a numerical model

A wastewater treatment using a biofilm airlift suspension reactor with biomass attached to supports: a numerical model

Nitrificación en reactores biopelícula de membrana tubular permeable a gases

Effect of oxygen gradients on the activity and microbial community structure of a nitrifying, membrane‐aerated biofilm

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