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Tazi-Pain A.,Veolia | Thaure D.,Pirelli SpA | Moeslang H.,Aquantis GmbH | Buisson H.,Kruger Inc
Water Science and Technology | Year: 2011

Twelve years after the first full scale municipal application in Europe of membrane bioreactor (MBR) technology, the process is now accepted as a technology of choice for wastewater treatment, and the market is showing sustained growth. However early misconceptions about the technology are persistent and false statements are commonly encountered in articles and conferences, generating unnecessary research efforts or even fuelling either fascination or scepticism with regards to the technology, which is ultimately detrimental to the perception of the process by water professionals. We try to provide some factual and rational clarifications on ten issues which are often wrongly reported about MBR technology. © IWA Publishing 2010.


Lackner S.,Technical University of Denmark | Lackner S.,TU Munich | Lackner S.,Aquantis GmbH | Terada A.,Technical University of Denmark | And 4 more authors.
Water Research | Year: 2010

Nitrogen removal via nitrite has gained increasing attention in recent years due to its potential cost savings. Membrane-aerated biofilm reactors (MABRs) are one potential technology suitable to achieve nitritation. In this study we compared lab scale MABRs with conventional biofilm reactors to evaluate the influence of environmental conditions and operational parameters on nitritation performance. The oxygen mass transfer rate is postulated as a crucial parameter to control nitritation in the MABR: Clean water measurements showed significant underestimation of the total oxygen mass transfer, however, accurate determination of the oxygen mass transfer coefficient (km) of the system could be achieved by adjusting the liquid-phase mass transfer resistance in the constructed model. Batch experiments at different initial ammonium concentrations revealed that the conventional biofilm geometry was superior for nitritation compared to MABRs. These differences were reflected well in estimates of the oxygen affinity constants of the key microbial players, AOB and NOB (KO,AOB < KO,NOB (in both systems) and KO,NOB values smaller in the MABR vs. the conventional biofilm system). It also appeared that - in addition to oxygen limitation - the absolute and relative substrate concentrations in the biofilm (esp. of oxygen) are very important for successful nitritation. Initial biomass composition, furthermore, impacted reactor performance in the MABR systems indicating the need for appropriate inoculum choice. © 2010 Elsevier Ltd.


Odegaard H.,Norwegian University of Science and Technology | Mende U.,Aquantis GmbH | Skjerping E.O.,KrugerKaldnes AS | Simonsen S.,KrugerKaldnes AS | And 2 more authors.
Desalination and Water Treatment | Year: 2012

The paper describes a tertiary treatment method (intended for water reuse) based on the moving bed biofilm reactor (MBBRTM), followed by a high-rate biomass separation step such as disc filter, DAF or Actiflo and followed by UF. Results from an experimental period carried out in pilot scale at the Gardermoen WWTP in Norway are described. Focus was on the use of the Hydrotech disc filter in combination with a contained, hollow fiber, outside-in ultrafiltration membrane unit. Different coagulation scenarios were tested and compared to the one based on the effluent from the full scale plant that uses coagulation/flocculation and DAF after the MBBR. It is concluded that the MBBR - high rate separation - UF process (the TERFLEX® process) offers an interesting and competitive alternative to the activated sludge based MBR. The best result when the UF membrane was used after primary biomass separation by DAF. The use of disc filter as the high rate biomass process ahead of the UF offers a very compact solution. © 2012 Desalination Publications. All rights reserved.


Terada A.,Technical University of Denmark | Terada A.,Tokyo University of Agriculture and Technology | Lackner S.,Technical University of Denmark | Lackner S.,Aquantis GmbH | And 2 more authors.
Environmental Microbiology | Year: 2010

The link between nitritation success in a membrane-aerated biofilm reactor (MABR) and the composition of the initial ammonia- and nitrite-oxidizing bacterial (AOB and NOB) population was investigated. Four identically operated flat-sheet type MABRs were initiated with two different inocula: from an autotrophic nitrifying bioreactor (Inoculum A) or from a municipal wastewater treatment plant (Inoculum B). Higher nitritation efficiencies (NO 2 --N/NH 4 +-N) were obtained in the Inoculum B- (55.2-56.4%) versus the Inoculum A- (20.2-22.1%) initiated reactors. The biofilms had similar oxygen penetration depths (100-150 μm), but the AOB profiles [based on 16S rRNA gene targeted real-time quantitative PCR (qPCR)] revealed different peak densities at or distant from the membrane surface in the Inoculum B- versus A-initiated reactors, respectively. Quantitative fluorescence in situ hybridization (FISH) revealed that the predominant AOB in the Inoculum A- and B-initiated reactors were Nitrosospira spp. (48.9-61.2%) versus halophilic and halotolerant Nitrosomonas spp. (54.8-63.7%), respectively. The latter biofilm displayed a higher specific AOB activity than the former biofilm (1.65 fmol cell -1 h -1 versus 0.79 fmol cell -1 h -1). These observations suggest that the AOB and NOB population compositions of the inoculum may determine dominant AOB in the MABR biofilm, which in turn affects the degree of attainable nitritation in an MABR. © 2010 Society for Applied Microbiology and Blackwell Publishing Ltd.


Pellicer-Nacher C.,Technical University of Denmark | Sun S.,Technical University of Denmark | Sun S.,Tongji University | Lackner S.,Technical University of Denmark | And 6 more authors.
Environmental Science and Technology | Year: 2010

One-stage autotrophic nitrogen (N) removal, requiring the simultaneous activity of aerobic and anaerobic ammonium oxidizing bacteria (AOB and AnAOB), can be obtained in spatially redox-stratified biofilms. However, previous experience with Membrane-Aerated Biofilm Reactors (MABRs) has revealed a difficulty in reducing the abundance and activity of nitrite oxidizing bacteria (NOB), which drastically lowers process efficiency. Here we show how sequential aeration is an effective strategy to attain autotrophic N removal in MABRs: Two separate MABRs, which displayed limited or no N removal under continuous aeration, could remove more than 5.5 g N/m2/day (at loads up to 8 g N/m2/day) by controlled variation of sequential aeration regimes. Daily averaged ratios of the surficial loads of O2 (oxygen) to NH4 + (ammonium) (LO2/LNH4) were close to 1.73 at this optimum. Real-time quantitative PCR based on 16S rRNA gene confirmed that sequential aeration, even at elevated average O2 loads, stimulated the abundance of AnAOB and AOB and prevented the increase in NOB. Nitrous oxide (N2O) emissions were 100-fold lower compared to other anaerobic ammonium oxidation (Anammox)-nitritation systems. Hence, by applying periodic aeration to MABRs, one-stage autotrophic N removal biofilm reactors can be easily obtained, displaying very competitive removal rates, and negligible N2O emissions. © 2010 American Chemical Society.


The invention relates to a fitting for distributing a gas flow to two or more flow ducts, wherein the fitting has an inlet connecting piece (20) and two or more separate outlet connecting pieces (21, 22), wherein upstream of each outlet connecting piece (21, 22) there is arranged a disc valve, wherein the disc valve inserts (15, 16) of two or more disc valves are kinematically coupled, and to a method for cleaning filter elements (4) immersed in a basin (1), in particular diaphragm filters, by aeration of the filter elements by means of gas bubbles which are introduced into the basin (1) below the filter elements (4) via aerators (5), wherein a gas flow for aerating the filter elements (4) is generated by means of a blower (7), wherein the gas flow is distributed by means of a fitting to two or more aerators (5), wherein the distribution of the gas flow takes place discontinuously, such that a pulsed aeration of the filter elements (4) of varying duration takes place at irregular intervals.

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