Mechanism of charged pollutants removal in an ion exchange membrane bioreactor: Drinking water denitrification
TL;DR: By adjusting the ratio of co-ions between the biocompartment and the polluted water compartment, the magnitude and direction of each individual anion flux can be easily regulated, allowing for flexible process operation and control.
Abstract: The mechanism of anionic pollutant removal in an ion exchange membrane bioreactor (IEMB) was studied for drinking water denitrification. This hybrid process combines continuous ion exchange transport (Donnan dialysis) of nitrate and its simultaneous bioreduction to gaseous nitrogen. A nonporous mono-anion permselective membrane precludes direct contact between the polluted water and the denitrifying culture and prevents secondary pollution of the treated water with dissolved nutrients and metabolic products. Complete denitrification may be achieved without accumulation of NO3− and NO2− ions in the biocompartment. Focus was given to the effect of the concentration of co-ions, counterions, and ethanol on the IEMB performance. The nitrate overall mass transfer coefficient in this hybrid process was found to be 2.8 times higher compared to that in a pure Donnan dialysis process without denitrification. Furthermore, by adjusting the ratio of co-ions between the biocompartment and the polluted water compartment, the magnitude and direction of each individual anion flux can be easily regulated, allowing for flexible process operation and control. Synthetic groundwater containing 135–350 mg NO3− L−1 was treated in the IEMB system. A surface denitrification rate of 33 g NO3− per square meter of membrane per day was obtained at a nitrate loading rate of 360 g NO3− m−3d−1, resulting in a nitrate removal efficiency of 85%. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 71: 245–254, 2000/2001.
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01 Jan 2003
TL;DR: Cicek et al. as discussed by the authors summarized the potential applications of the membrane bioreactor technology for the treatment of wastewater from agricultural sources and used it for treating manure and wastewater from livestock operations to levels suitable for direct reuse or safe discharge to surface water bodies.
Abstract: Cicek, N. 2003. A review of membrane bioreactors and their potential application in the treatment of agricultural wastewater. Canadian Biosystems Engineering/Le génie des biosystèmes au Canada 45: 6.37-6.49. Membrane Bioreactors (MBRs) can be broadly defined as systems integrating biological degradation of waste products with membrane filtration. They have proven quite effective in removing organic and inorganic contaminants as well as biological entities from wastewater. Advantages of the MBR include good control of biological activity, high quality effluent free of bacteria and pathogens, smaller plant size, and higher organic loading rates. Current applications include water recycling in buildings, wastewater treatment for small communities, industrial wastewater treatment, and landfill leachate treatment. This paper summarizes the potential applications of the MBR technology for the treatment of wastewater from agricultural sources. Anaerobic digestion coupled with an aerobic/anoxic membrane bioreactor could be utilized for treating manure and wastewater from livestock operations to levels suitable for direct reuse or safe discharge to surface water bodies. Wastewater generated from industries such as slaughterhouses, meat, dairy, egg, and potato processing and liquor production could potentially be treated with MBRs resulting in compact systems producing high quality reusable water. Also effective removal of nitrates, herbicides, pesticides, and endocrine disrupting compounds may be achieved by MBRs.
191 citations
Cites background from "Mechanism of charged pollutants rem..."
...1994), whereas the other configuration used the membrane as a semi-permeable ion exchange barrier for nitrate transfer (Fonseca et al. 2000; Mansell and Schroeder 1998; Velizarov et al. 2000)....
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...…the membrane as a cell recycle tool in an external MBR set-up (Barreiros et al. 1998; Delanghe et al. 1994), whereas the other configuration used the membrane as a semi-permeable ion exchange barrier for nitrate transfer (Fonseca et al. 2000; Mansell and Schroeder 1998; Velizarov et al. 2000)....
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TL;DR: In this paper, the authors reviewed research regarding how numerous process parameters impact biofouling rates and, in particular, the possible contribution of microbial products to bio fouling, and assessed their potential affect on membrane fouling.
Abstract: A membrane bioreactor (MBR) combines membrane separation and biological treatment, normally involving the activated sludge process, in municipal wastewater treatment. Despite excellent performance over years of full‐scale operation, the interactions between microbes and the membrane in the MBR process, which determine its design and operational criteria, remain unclear. This report reviewed research regarding how numerous process parameters impact biofouling rates and, in particular, the possible contribution of microbial products to biofouling. This study also characterized different fractions of microbial products and assessed their potential affect on membrane fouling.
115 citations
Cites methods from "Mechanism of charged pollutants rem..."
...New functional membranes, such as the ionexchange membrane (20) or enzyme-immobilized bilayer membranes (21), have been effectively employed in MBR....
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TL;DR: In this paper, the authors present a review of the research to date appraising advantages and disadvantages associated with each configuration whilst also identifying areas that require further research and consequently assessing which nitrate removal MBR technologies will prevail for the future.
113 citations
Cites background or methods from "Mechanism of charged pollutants rem..."
...Corroborating these findings, Velizarov et al. (2000) reported ethanol concentrations in the effluent below the detection limit of 1 mg l, although when ethanol concentrations exceeded 450 mg l in the biocompartment (Table 2....
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...Mannheim enzymatic method adopted by Velizarov et al. (2001) in another drinking...
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...Corroborating these findings, Velizarov et al. (2000) reported ethanol concentrations in the effluent below the detection limit of 1 mg l-1, although when ethanol concentrations exceeded 450 mg l-1 in the biocompartment (Table 2.2), ethanol could be determined in the product water....
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...The authors also concluded that by adjusting the co-ion ratio, nitrate flux can be easily controlled (Velizarov et al., 2000)....
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TL;DR: An overview of the main membrane-assisted processes that can be used for the removal of toxic inorganic anions from drinking water supplies is provided in this article, with a focus on integrated process solutions, including the emerging issue of membrane bioreactors.
Abstract: This paper is designed to provide an overview of the main membrane-assisted processes that can be used for the removal of toxic inorganic anions from drinking water supplies. The emphasis has been placed on integrated process solutions, including the emerging issue of membrane bioreactors. An attempt is made to compare critically recently reported results, reveal the best existing membrane technologies and identify the most promising integrated membrane bio/processes currently being under investigation. Selected examples are discussed in each case with respect to their advantages and limitations compared to conventional methods for removal of anionic pollutants. The use of membranes is particularly attractive for separating ions between two liquid phases (purified and concentrated water streams) because many of the difficulties associated with precipitation, coagulation or adsorption and phase separation can be avoided. Therefore, membrane technologies are already successfully used on large-scale for removal of inorganic anions such as nitrate, fluoride, arsenic species, etc. The concentrated brine discharge and/or treatment, however, can be problematic in many cases. Membrane bioreactors allow for complete depollution but water quality, insufficiently stable process operation, and economical reasons still limit their wider application in drinking water treatment. The development of more efficient membranes, the design of cost-effective operating conditions, especially long-term operations without or with minimal membrane inorganic and/or biological fouling, and reduction of the specific energy consumption requirements are the major challenges.
107 citations
Cites methods from "Mechanism of charged pollutants rem..."
...This concept was first demonstrated in synthetic waters (Table 5) for the removal and bioconversion of nitrate to harmless nitrogen gas using Neosepta ACS mono-anion permselective membrane and ethanol as the carbon source (Fonseca et al. 2000; Velizarov et al. 2000)....
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TL;DR: The IEMB process, which combines Donnan dialysis and simultaneous biological degradation of both pollutants, proved to remove effectively perchlorate and nitrate while preserving the water composition with respect to other ions, thus avoiding secondary contamination of the treated water.
100 citations
References
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25 May 1984TL;DR: An overview of diffusion and separation processes brings unsurpassed, engaging clarity to this complex topic as mentioned in this paper, which is a key part of the undergraduate chemical engineering curriculum and at the core of understanding chemical purification and reaction engineering.
Abstract: This overview of diffusion and separation processes brings unsurpassed, engaging clarity to this complex topic. Diffusion is a key part of the undergraduate chemical engineering curriculum and at the core of understanding chemical purification and reaction engineering. This spontaneous mixing process is also central to our daily lives, with importance in phenomena as diverse as the dispersal of pollutants to digestion in the small intestine. For students, Diffusion goes from the basics of mass transfer and diffusion itself, with strong support through worked examples and a range of student questions. It also takes the reader right through to the cutting edge of our understanding, and the new examples in this third edition will appeal to professional scientists and engineers. Retaining the trademark enthusiastic style, the broad coverage now extends to biology and medicine.
5,195 citations
TL;DR: In this paper, the authors reviewed the developments in the field of nitrate removal processes and concluded that ion exchange and biological denitrification are more acceptable for ground water than reverse osmosis.
Abstract: Nitrate concentrations in surface water and especially in ground water have increased in Canada, the United States, Europe, and other areas of the world. This trend has raised concern because nitrates cause methemoglobinemia in infants. Several treatment processes including ion exchange, biological denitrification, chemical denitrification, reverse osmosis, electrodialysis, and catalytic denitrification can remove nitrates from water with varying degrees of efficiency, cost, and ease of operation. Available technical data, experience, and economics indicate that ion exchange and biological denitrification are more acceptable for nitrate removal than reverse osmosis. Ion exchange is more viable for ground water while biological denitrification is the preferred alternative for surface water. This paper reviews the developments in the field of nitrate removal processes.
666 citations
TL;DR: Three generic membrane processes within bioreactors: for separation and recycle of solids; for bubbleless aeration of the bioreactor; and for extraction of priority organic pollutants from hostile industrial wastewaters are developed.
Abstract: Combining membrane technology with biological reactors for the treatment of municipal and industrial wastewaters has led to the development of three generic membrane processes within bioreactors: for separation and recycle of solids; for bubbleless aeration of the bioreactor; and for extraction of priority organic pollutants from hostile industrial wastewaters. Commercial aerobic and anaerobic membrane separation bioreactors already provides a small footprint alternative to conventional biological treatment methods, producing a high-quality effluent at high organic loading rates. Both the bubbleless aeration and extractive membrane bioreactors are in the development stages. The former uses gas-permeable membranes to improve the mass transfer of oxygen to the bioreactor by providing bubbleless oxygen. By using a silicon membrane process, extractive membrane bioreactors transfer organic pollutants from chemically hostile wastewaters to a nutrient medium for subsequent biodegradation. All three membrane bioreactor (MBR) processes are comparatively and critically reviewed.
330 citations
TL;DR: Permselectivity of specific anions through the anion exchange membranes is governed mainly by the balance of hydration energy of anions with hydrophilicity of the membranes, partially by hydrated ionic size of the anions, except the membranes having an oppositely charged layer on the membrane surface.
271 citations
TL;DR: A kinetic model for nitrate competitive inhibition of nitrite reduction is proposed, which shows that the regulation mechanism that shifts the electron flow between the two terminal reductases is readily reversible and does not change their relative maximum reduction rates.
Abstract: A pure culture of Pseudomonas fluorescens was used as a model system to study the kinetics of denitrification. An exponentially growing culture was harvested and resuspended in an anoxic acetate solution buffered with K/Na phosphate at pH values of 6.6, 7.0, 7.4, and 7.8. The temperature was kept at 28 degrees C in all assays. Nitrate pulses of approximately 0.2 mg N/L caused nitrite to accumulate due to a faster rate of nitrate reduction over nitrite reduction. The rate of nitrate reduction was observed to depend on its concentration as predicted by the Michaelis-Menten equation. At nonlimiting nitrate concentrations, nitrite reduction was described by the same equation. Otherwise, nitrite reduction also depended on nitrate concentration. Consequently, nitrate and nitrite reductions compete with each other for the oxidation of common electron donors. A kinetic model for nitrate competitive inhibition of nitrite reduction is proposed. The model was used to interpret the nitrate and nitrite profiles observed at the four pH values: the optimum pH value was 7.0 in both cases; the affinity for nitrite was also not affected by the medium pH in the range of values 6.6 to 7.4 (K(mNO(3) ) = 0.04 mg N/L); the affinity for nitrite was also not affected by the medium pH in the range of values 6.6 to 7.4 (K(mNO(2) ) = 0.06 mg N/L), but it decreased sharply for the pH value of 7.8. Although the ratio between the two maximum reduction rates (V(max NO(2) )/V(max NO(3) )) is constant, nitrite accumulation depends on the medium pH value. Therefore, the regulation mechanism that shifts the electron flow between the two terminal reductases is readily reversible and does not change their relative maximum reduction rates. (c) 1995 John Wiley & Sons, Inc.
199 citations