backwash Articles
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Effect of cycle run time of backwash and relaxation on membrane fouling removal in submerged membrane bioreactor treating sewage at higher flux
Intermittent backwashing and relaxation are mandatory in the membrane bioreactor (MBR) for its effective operation. The objective of the current study was to evaluate the effects of run-relaxation and run-backwash cycle time on fouling rates. Furthermore, comparison of the effects of backwashing and relaxation on the fouling behavior of membrane in high rate submerged MBR. The study was ...
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Application of backwashing with demineralized water for UF fouling control in UF-RO desalination
The effectiveness of demineralized water backwash on ultrafiltration (UF) fouling control of seawater is investigated in this study. Fouling experiments for two different backwashes (UF permeate and demineralized water) were conducted at three fluxes: 120, 180 and 240 L/(h m2) to compare their fouling control efficiency on UF membranes. Results show that backwashing with demineralized water ...
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Flux-step method for the assessment of operational conditions in a submerged membrane bioreactor
A flux-step method was used for monitoring the pressure variation in a solids separation membrane at different operating conditions. A submerged membrane bioreactor pilot plant, used during the short-term tests, was used to purify actual restaurant wastewater. The influence of membrane backwash and relaxation on the variation of pressure variation was also evaluated. In order to reduce the ...
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Numerical and experimental investigation for cleaning process of submerged outside-in hollow fiber membrane
Membrane fouling has limited extensive applications for hollow fiber membranes in water treatment. Backwashing and air scouring can effectively solve this problem in the submerged outside-in hollow fiber membrane system. In this study, variation of the fouling layer on the membrane surface during backwashing and the impact of shear stress caused by air scouring on fouling removal were ...
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Optimization of direct-osmosis–high-salinity cleaning for reverse osmosis fouling control in water reuse
This paper focuses on the systematic approach adopted towards optimizing the salt consumption when using direct-osmosis–high-salinity (DO-HS) cleaning method for RO membranes in water reuse application. Trials were carried out on a pilot RO system with a capacity of 50 m3/day. Initially, proof of concept for the DO-HS method in water reuse application was established wherein the profile of ...
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Bench-scale study of ultrafiltration membranes for evaluating membrane performance in surface water treatment
Currently, there is no standard bench-scale dead-end ultrafiltration (UF) testing system. The aim of the present study was to design and build a bench-scale hollow fiber UF system to assess the impact of operational parameters on membrane performance and fouling. A bench-scale hollow fiber UF system was built to operate at a constant flux (±2% of the set-point flux) and included automated ...
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Forward osmosis membrane fouling and cleaning for wastewater reuse
Membrane fouling properties and different physical cleaning methods for forward osmosis (FO) and reverse osmosis (RO) laboratory-scale filtration systems were investigated. The membrane fouling, with respect to flux reduction, was lower in FO than in RO when testing an activated sludge effluent. Cross-flow velocity, air-scouring, osmotic backwashing and effect of a spacer were compared to ...
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Pilot scale evaluation of biofiltration as an innovative pre-treatment for ultrafiltration membranes for drinking water treatment
Fouling remains one of the major constraints on the use of low pressure membranes in drinking water treatment. Work over the last few years has shown the importance of biopolymers (carbohydrates and protein-like material) as foulants for ultrafiltration (UF) membranes. The purpose of this study was to investigate at pilot scale the use of rapid biofiltration (without prior coagulation or ozone ...
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Ceramic membrane ultrafiltration of natural surface water with ultrasound enhanced backwashing
Ultrafiltration membrane cleaning with ultrasound enhanced backwashing was investigated with two ceramic membrane systems in parallel. One of them was subjected to ultrasound during backwashing, the other acted as a reference system. The feed water was directly taken from a creek with a sedimentation process as only pre-treatment. The cleaning performance was improved with ultrasound but after 3 ...
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Performances and fouling control of a flat sheet membrane in a MBR pilot-plant
This paper deals with the performance and the optimisation of the hydraulic operating conditions of the A3 Water Solutions flat sheet membrane technology in a MBR pilot-plant to achieve a satisfying fouling control and also a reduction in the required aeration. Two vertically stacked modules were tested at pilot-scale at Anjou Recherche under typical biological operating conditions (mixed liquor ...
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Ceramic membranes for water treatment
Ceramic membranes, different in pore size and membrane material, were applied to remove particulate and dissolved matter from different spent filter backwash water types as well as from dam water. The study was conducted in pilot scale under conditions typical for waterworks at a dam water treatment plant. A comparison of different ceramic membranes implied that total membrane resistance was more ...
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Effects of tannic acid on membrane fouling and membrane cleaning in forward osmosis
The fouling behavior during forward osmosis (FO) was investigated. Tannic acid was used as a model organic foulant for natural organic matter analysis since the main characteristics are similar, and calcium ions were added at different concentrations to explore the anti-pollution capability of FO membranes. The initial permeate flux and calcium ions strength were varied in different operating ...
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Development of a model-based control system for membrane filtration process
Reduction of operational cost and certification of safety for treated water are required for the membrane filtration process for drinking water. Therefore a model-based control system is developed to reduce operational cost. A process model is used for the model-based control system that calculates the transmembrane pressure (TMP) in the future. This allows the model-based control system to ...
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Performance of a GAC and ultrafiltration hybrid process under high humidity and temperature conditions
The performance of a granular activated carbon (GAC) and ultrafiltration (UF) hybrid process and changes in UF membrane properties were studied. This hybrid process reduced total organic carbon by 59 ± 12% and UV absorbance (UV254) by 88 ± 31%, with GAC accounting for 93 and 98% of total reduction, respectively. Selected pharmaceuticals and personal care products were reduced by 32–92% during the ...
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Cake porosity analysis using 1D–3D fractal dimensions in coagulation–microfiltration of NOM
Fouling during coagulation–ceramic microfiltration of natural organic matter was investigated. Two process configurations (inline coagulation (IC) and tank coagulation (TC)) and two process conditions (types of coagulants–aluminum-based PAX and iron-based PIX–and G-values) were studied. The rate of irreversible fouling corresponding to the increase of initial transmembrane ...
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Preparation and characterization of fouling-resistant composite membranes based on layer-by-layer self-assembly technique
This paper introduces a versatile approach for surface modification of 621-terylene filtration fabric (FF) self-assembled by a dynamic layer-by-layer technique. The hexadecyl trimethyl ammonium bromide (HTAB) and cross-linked polyvinyl alcohol microspheres (PVA-MS) were alternatively deposited on support membrane under a pressure of 0.01 MPa to modify FF. Morphological changes and hydrophilicity ...
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Knowledge-based system for automatic MBR control
MBR technology is currently challenging traditional wastewater treatment systems and is increasingly selected for WWTP upgrading. MBR systems typically are constructed on a smaller footprint, and provide superior treated water quality. However, the main drawback of MBR technology is that the permeability of membranes declines during filtration due to membrane fouling, which for a large part ...
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Evaluation of an emerging water treatment technology: ceramic membranes
Historically, low-pressure membranes (microfiltration (MF) and ultrafiltration (UF)) used in potable water treatment are made of polymers (polysulfone (PS), polypropylene (PP), polyethersulfone (PES), polyvinylidene fluoride (PVDF) etc). Recently, membranes made of ceramic materials (aluminium oxide) have been developed by MetaWater (Japan), Kubota (Japan) and others and is being marketed in the ...
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Irreversible fouling of membrane bioreactors due to formation of a non-biofilm gel layer
Extra-cellular polymeric substances (EPS), known to contribute to fouling in membrane bio-reactors (MBRs), are generally divided into bound and free EPS. The free EPS are able to form a gel layer on the membrane active surface. The mechanisms involved in formation of such layer and its effects on performance of the MBR membranes were studied. The free EPS, extracted by centrifugation and ...
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Biological filtration of poor quality brackish water reducing Reverse Osmosis membrane fouling
Abstract A primary limitation in applying Reverse Osmosis (RO) is loss of performance caused by membrane fouling resulting from compounds that bacteria can use as energy or nutrient sources. When these compounds enter RO membranes, they are capable of sustaining extensive bacterial growths on the membrane sheets as well as within feed channel spacers. This leads to the entrapment of particles ...
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