Fate and impact of organics in an immersed membrane bioreactor applied to brine denitrification and ion exchange regeneration.
TL;DR: It was concluded that a denitrification MBR was an appropriate technology for IEX spent brine recovery and reuse and compared to that determined when using freshly produced brine for regeneration.
Abstract: The application of membrane bioreactors (MBRs) to brine denitrification for ion exchange regeneration has been studied. The developed culture was capable of complete brine denitrification at 50 gNaCl.l −1 . Denitrification reduced to c.60% and c.70% when salinity was respectively increased to 75 and 100 g.l −1 , presumed to be due to reduced growth rate and the low imposed solids retention time (10 days). Polysaccharide secretion was not induced by stressed cells following salt shocking, implying that cell lysis did not occur. Fouling propensity, monitored by critical flux, was steady at 12–15 l.m −2 .h −1 during salinity shocking and after brine recirculation, indicating that the system was stable following perturbation. Low molecular weight polysaccharide physically adsorbed onto the nitrate selective anion exchange resin during regeneration reducing exchange capacity by c.6.5% when operating up to complete exhaustion. However, based on a breakthrough threshold of 10 mgNO 3 − -N.l −1 the exchange capacity was comparative to that determined when using freshly produced brine for regeneration. It was concluded that a denitrification MBR was an appropriate technology for IEX spent brine recovery and reuse.
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TL;DR: Results from this study demonstrate that dissolved methane recovery could increase net electrical production from low temperature anaerobic processes by ca.
Abstract: This paper demonstrates the potential for recovering dissolved methane from low temperature anaerobic processes treating domestic wastewater. In the absence of methane recovery, ca. 45% of the produced methane is released as a fugitive emission which results in a net carbon footprint of −0.47 kg CO 2e m −3 . A poly-di-methyl-siloxane (PDMS) membrane contactor was applied to support sweep gas desorption of dissolved methane using nitrogen. The dense membrane structure controlled gaseous mass transfer thus recovery was maximised at low liquid velocities. At the lowest liquid velocity, V L , of 0.0025 m s −1 , 72% of the dissolved methane was recovered. A vacuum was also trialled as an alternative to sweep-gas operation. At vacuum pressures below 30 mbar, reasonable methane recovery was observed at an intermediate V L of 0.0056 m s −1 . Results from this study demonstrate that dissolved methane recovery could increase net electrical production from low temperature anaerobic processes by ca. +0.043 kWh e m −3 and reduce the net carbon footprint to +0.01 kg CO 2e m −3 . However, further experimental work to optimise the gas-side hydrodynamics is required as well as validation of the long-term impacts of biofouling on process performance.
102 citations
20 Oct 2014
TL;DR: In this article, the authors present the fundamentals of fouling issues in membrane separations, with specific regard to membrane fouling in Membrane Bioreactors and the most frequently applied preventive-control strategies.
Abstract: Membrane fouling is one of the most important considerations in the design and operation of membrane systems as it affects pretreatment needs, cleaning requirements, operating conditions, cost and performance. Given that membrane fouling represents the main limitation to membrane process operation, it is unsurprising that the majority of membrane material and process research and development conducted is dedicated to its characterization and amelioration. This work presents the fundamentals of fouling issues in membrane separations, with specific regard to membrane fouling in Membrane Bioreactors (MBRs) and the most frequently applied preventive-control strategies. Feed pretreatment, physical and chemical cleaning protocols, optimal operation of MBR process and membrane surface modification are presented and discussed in detail. Membrane fouling is the major obstacle to the widespread application of the MBR technology and, therefore, fouling preventive-control strategies is a hot issue that strongly concerns not only the scientific community, but industry as well.
97 citations
TL;DR: This work presents a strategy to photocatalytically reduce nitrate in IX brine, thereby extending the use of the brine and investigating the impact of residual FA for brine reuse.
Abstract: Nitrate is often removed from groundwater by ion exchange (IX) before its use as drinking water. Accumulation of nitrate in IX brine reduces the efficiency of IX regeneration and the useful life of the regeneration brine. For the first time, we present a strategy to photocatalytically reduce nitrate in IX brine, thereby extending the use of the brine. Titanium dioxide (Evonik P90), acting as photocatalyst, reduced nitrate effectively in both synthetic brines and sulfate-removed IX brine when formic acid (FA) was used as the hole scavenger (i.e., electron donor) and the initial FA to nitrate molar ratio (IFNR) was 5.6. Increasing the NaCl level in the synthetic brine slowed the nitrate reduction rate without affecting by-product selectivity of ammonium and gaseous N species (e.g., N2, N2O). In a non-modified IX brine, nitrate removal was greatly inhibited owing to the presence of sulfate, which competed with nitrate for active surface sites on P90 and induced aggregation of P90 nanoparticles. After removing sulfate through barium sulfate precipitation, nitrate was effectively reduced; approximately 3.6 × 1024 photons were required to reduce each mole of nitrate to 83% N Gases and 17% NH4+. To make optimum use of FA and control the residual FA level in treated brine, the IFNR was varied. High IFNRs (e.g., 4, 5.6) were found to be more efficient for nitrate reduction but left higher residual FA in brine. IX column tests were performed to investigate the impact of residual FA for brine reuse. The residual FA in the brine did not significantly affect the nitrate removal capacity of IX resins, and formate contamination of treated water could be eliminated by rinsing with one bed volume of fresh brine.
90 citations
TL;DR: In this paper, an overview of different types of brine effluents, their sources and characteristics are discussed, as well as impacts of brines on the environment and management options related to their characteristics.
Abstract: Brine discharge is one of the largest sources of wastewater from industrial processes. Because of the environmental impacts arising from improper treatment of brine discharge and more rigorous regulations of pollution control, industries have started to focus on waste minimization and improving the process of wastewater treatment. Several approaches have been proposed to provide a strategy for brine handling by recovering both brine and water or to remove pollutant components so it complies with environmental regulations when discharged. One of the most promising alternatives to brine disposal is reusing the brine, which results in reduction of pollution, minimizing waste volume and salt recovery. The brine may also contain valuable components that could be recovered for profitable use. Also, water recovery from brine effluent is generally performed to save water. In the case of rejected brine from desalination plants, water recovery from higher brine concentrations has huge potential for salt production. This paper gives an overview of different types of brine effluents, their sources and characteristics. Also discussed are impacts of brine on the environment and management options related to their characteristics.
50 citations
TL;DR: This demonstrates that ammonia rich wastewaters can facilitate chemically enhanced CO2 separation which eliminates the need for costly exogenic chemicals or complex chemical handling which are critical barriers to implementation of chemical absorption.
Abstract: The use of ammonia (NH3) rich wastewaters as an ecological chemical absorption solvent for the selective extraction of carbon dioxide (CO2) during biogas upgrading to 'biomethane' has been studied. Aqueous ammonia absorbents of up to 10,000 gNH3 m(-3) demonstrated CO2 absorption rates higher than recorded in the literature for packed columns using 20,000-80,000 g NH3 m(-3) which can be ascribed to the process intensification provided by the hollow fibre membrane contactor used in this study to support absorption. Centrifuge return liquors (2325 g m(-3) ionised ammonium, NH4(+)) and a regenerant (477 gNH4(+) m(-3)) produced from a cationic ion exchanger used to harvest NH4(+) from crude wastewater were also tested. Carbon dioxide fluxes measured for both wastewaters compared reasonably with analogue ammonia absorption solvents of equivalent NH3 concentration. Importantly, this demonstrates that ammonia rich wastewaters can facilitate chemically enhanced CO2 separation which eliminates the need for costly exogenic chemicals or complex chemical handling which are critical barriers to implementation of chemical absorption. When testing NH3 analogues, the potential to recover the reaction product ammonium bicarbonate (NH4HCO3) in crystalline form was also illustrated. This is significant as it suggests a new pathway for ammonia separation which avoids biological nitrification and produces ammonia stabilised into a commercially viable fertiliser (NH4HCO3). However, in real ammonia rich wastewaters, sodium bicarbonate and calcium carbonate were preferentially formed over NH4HCO3 although it is proposed that NH4HCO3 can be preferentially formed by manipulating both ion exchange and absorbent chemistry.
42 citations
Cites methods from "Fate and impact of organics in an i..."
...…of clinoptilolite resin (RS Minerals, Guisborough, UK) and was prepared by passing a 50 gNaCl L -1 (99%, Fisher Chemicals, Loughborough, UK) regenerant through the column at 5 bed volumes per hour (Bv h-1) for 30 minutes followed by a DI rinse at 5 Bv h-1 for 60 minutes (McAdam et al., 2010) (Fig....
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References
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TL;DR: The lipid decomposition studies in frozen fish have led to the development of a simple and rapid method for the extraction and purification of lipids from biological materials that has been applied to fish muscle and may easily be adapted to use with other tissues.
Abstract: Lipid decomposition studies in frozen fish have led to the development of a simple and rapid method for the extraction and purification of lipids from biological materials. The entire procedure can...
46,099 citations
TL;DR: Wimpenny & Colasanti (1997) have suggested that biofilm structure is largely determined by the concentration of substrate, and postulated that such differences also validate at least three conceptual models of biofilms – heterogeneous mosaics, structures penetrated by water channels, and dense confluent bioFilms.
Abstract: Biofilms probably comprise the normal environment for most microbial cells in many natural and artificial habitats, and as such are complex associations of cells, extracellular products and detritus either trapped within the biofilm or released from cells which have lysed as the biofilm ages (Christensen, 1989). The main ‘cement ’ for all these cells and products is the mixture of polysaccharides secreted by the cells established within the biofilm. Probably the nearest analogy is processed food, in which a mixture of macromolecules of all types interact in variousways to form a recognizable structure. Within such a structure, cells, water, ions and soluble low-and high-molecular-mass products are trapped. In many biofilms, as in food, the hydrated polysaccharides may be in a semi-solid state. The major component in the biofilm matrix is water – up to 97% (Zhang et al., 1998), and the characteristics of the solvent are determined by the solutes dissolved in it. The exact structure of any biofilm is probably a unique feature of the environment in which it develops. As pointed out by Stoodley et al. (1999a), nutritional and physical conditions greatly affect the nature of laboratory biofilms and this is equally true for other types. Wimpenny & Colasanti (1997) have also suggested that biofilm structure is largely determined by the concentration of substrate. They further postulated that such differences also validate at least three conceptual models of biofilms – heterogeneous mosaics, structures penetrated by water channels, and dense confluent biofilms.
1,702 citations
Book•
01 Jan 2006
TL;DR: The second edition of the MBR Book as mentioned in this paper provides more content than the first edition, with more than 120 contributors from the academic research and municipal/industrial practitioner communities, covering all important aspects of Membrane BioReactors in water and waste water treatment.
Abstract: A Membrane BioReactor (MBR) is the combination of a membrane process (e.g. microfiltration/ ultrafiltration) with a suspended growth bioreactor. When used with domestic wastewater, MBR processes can produce effluent of high enough quality to be discharged to waterways, or to be reclaimed for urban irrigation. Other advantages of MBRs over conventional processes include small footprint, easy retrofit and upgrade of old wastewater treatment plants.
The MBR Book covers all important aspects of Membrane BioReactors in water and waste water treatment, from the fundamentals of the processes via design principles to MBR technologies. Industrial case studies help interpret actual results and give pointers for best practice. Useful appendices provide data on commercial membranes and international membrane organizations.
The MBR book enables readers to:
Understand the fundamental processes involved in membrane and biotreatment technologies
Compare and contrast design options and work through sample calculations
Review commercial MBR systems in terms of specific applications
Learn from case studies involving domestic and industrial effluent treatment and recycling
Analyze process design, operation, performance and maintenance to draw conclusions appropriate to their requirements
New to the second edition:
45% more content than the first edition.
Over 120 contributors from the academic research and municipal/industrial practitioner communities.
Review of MBR status in ten countries.
Expanded section on anaerobic MBRs, micropollutant fate and hybrid systems.
Simplified design methodology, with biokinetics for dynamic modelling and cost benefit analysis.
Expanded operation and maintenance section, informed by expert panel of practitioners offering more than 40 years combined experience.
Over 40 MBR membrane products described, with most of the technical specifications provided.
Over 50 case studies provided, including key design, performance, and operation and maintenance data in almost all cases.
Membrane Bioreactors are a major growth area in the water and waste water treatment industries
Internationally-known author, one of the leading senior experts in MBR research
Principles and practice, backed by industrial case studies
1,278 citations
"Fate and impact of organics in an i..." refers background or methods in this paper
...This appears counter-intuitive, based on the presence of accumulated 183 organics and challenges previous reports which link fouling propensity to elevated 184 concentrations of biopolymers in the bulk phase (Judd, 2006; Reid et al., 2006)....
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...Soluble microbial products 119 (SMP) were extracted according to the method described in Judd (2006) and 120 polysaccharide and protein concentration quantified using the phenol–sulphuric acid 121 method (Zhang et al., 1999) and modified Lowry method (Frølund et al., 1995) 122 respectively....
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TL;DR: The enzymatic activity of activated sludge was investigated with special emphasis on the localization of the enzymes in the sludge floc matrix, showing that the exoenzymes should be considered to be an integrated part of the EPS matrix rather than as direct indicators of the microbial activity or biomass.
Abstract: The enzymatic activity of activated sludge was investigated with special emphasis on the localization of the enzymes in the sludge floc matrix. Activated sludge from an advanced activated-sludge treatment plant, performing biological N and P removal, was used. An enzymatic fingerprint was established using a panel of six different enzymes. The fingerprint revealed peptidase as the most dominating specific enzyme tested. By monitoring sludge bulk enzymatic activity over a 3-month period using fluorescein diacetate as an enzyme substrate, considerable variations in activity were observed even over short periods (a few days). The variation in esterase activity was to some extent correlated to the presence of humic compounds in the sludge, but not to the sludge protein content. Comparison of full sludge enzyme activity to the activity of a batch-grown sludge culture indicated that enzymes accumulated in sludge flocs. A large proportion of the exoenzymes were immobilized in the sludge by adsorption in the extracellular polymeric substances (EPS) matrix. This was demonstrated by extraction of EPS from the activated sludge using cation exchange. Contemporary to the release of EPS a very large fraction of the exoenzymes was released into the water. This showed that the exoenzymes should be considered to be an integrated part of the EPS matrix rather than as direct indicators of the microbial activity or biomass.
1,266 citations
"Fate and impact of organics in an i..." refers methods in this paper
..., 1999) and modified Lowry method (Frølund et al., 1995) 122 respectively....
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...Soluble microbial products 119 (SMP) were extracted according to the method described in Judd (2006) and 120 polysaccharide and protein concentration quantified using the phenol–sulphuric acid 121 method (Zhang et al., 1999) and modified Lowry method (Frølund et al., 1995) 122 respectively....
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