Occurrence and removal of microbial indicators from municipal wastewaters by nine different MBR systems

2012 ◽  
Vol 66 (4) ◽  
pp. 865-871 ◽  
Author(s):  
Zakir M. Hirani ◽  
James F. DeCarolis ◽  
Geno Lehman ◽  
Samer S. Adham ◽  
Joseph G. Jacangelo
Keyword(s):  
Fecal Coliform ◽  
Polyvinylidene Fluoride ◽  
Coliform Bacteria ◽  
Membrane Pore ◽  
Microbial Indicators ◽  
Membrane Materials ◽  
Pore Sizes ◽  
Wide Range ◽  
Membrane Pore Size ◽  
The Impact

Nine different membrane bioreactor (MBR) systems with different process configurations (submerged and external), membrane geometries (hollow-fiber, flat-sheet, and tubular), membrane materials (polyethersulfone (PES), polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE)) and membrane nominal pore sizes (0.03–0.2 μm) were evaluated to assess the impact of influent microbial concentration, membrane pore size and membrane material and geometries on removal of microbial indicators by MBR technology. The log removal values (LRVs) for microbial indicators increased as the influent concentrations increased. Among the wide range of MBR systems evaluated, the total and fecal coliform bacteria and indigenous MS-2 coliphage were detected in 32, 9 and 15% of the samples, respectively; the 50th percentile LRVs were measured at 6.6, 5.9 and 4.5 logs, respectively. The nominal pore sizes of the membranes, membrane materials and geometries did not show a strong correlation with the LRVs.

scholarly journals Coalescence of Oil Droplets using Sponge-like Structure of Polyvinylidene Fluoride Membranes

2018 ◽  
Vol 23 (1) ◽  
Author(s):  
C. K. Chiam ◽  
M. Nurashiqin ◽  
K. Zykamilia ◽  
N. M. Ismail ◽  
K. Duduku ◽  
...  
Keyword(s):  
Size Distribution ◽  
Polyvinylidene Fluoride ◽  
Produced Water ◽  
Feed Solution ◽  
Transmembrane Pressure ◽  
Oil Droplets ◽  
Membrane Pore ◽  
Pore Sizes ◽  
Phase Inversion Technique ◽  
Membrane Pore Size

This work reports the effect of the membrane pore size distribution on the oil droplets size distribution in permeate using the polyvinylidene fluoride (PVDF) membranes. The sponge-like structures of the PVDF membranes were fabricated via the phase inversion technique using 30% v/v ethanol aqueous solution as coagulation medium. Water and polyethylene glycol (PEG1000) were used as the pore forming additives in the dope solutions. Microfiltration was employed to coalesce the oil droplets at the transmembrane pressure of 2.5 bar. Simulated alkaline-surfactant-polymer (ASP) produced water was tested as the feed solution. Results revealed that the PVDF membranes with sponge-like structure were formed. The additives in the dope solutions have induced the membranes to become thicker due to more porous, spongy and resilient structure. The membrane pore sizes increased with the presence of the additives in the dope solutions especially when larger molecular weight of the additive, i.e., PEG1000 was used. The mode of the oil droplets radius increased from 61.2 nm in the feed solution to 95.1, 356.2 and 1335 nm in the permeates by the corresponding membranes without additive, with water and PEG1000 as the additives. The membranes with larger pore sizes as well as more open structure were able to trap and coalesce more oil droplets which produced larger size of the oil droplets in the permeates.

Solvent Effects on the Synthesis of Polymeric Nanoparticles via Block Copolymer Self-Assembly Using Microporous Membranes

2020 ◽  
Vol 1000 ◽  
pp. 324-330
Author(s):  
Sri Agustina ◽  
Masayoshi Tokuda ◽  
Hideto Minami ◽  
Cyrille Boyer ◽  
Per B. Zetterlund
Keyword(s):  
Block Copolymer ◽  
Block Copolymers ◽  
Self Assembly ◽  
Polymeric Nanoparticles ◽  
Raft Polymerization ◽  
Membrane Emulsification ◽  
Membrane Pore ◽  
Novel Technique ◽  
Wide Range ◽  
Membrane Pore Size

The self-assembly of block copolymers has attracted attention for many decades because it can yield polymeric nanoobjects with a wide range of morphologies. Membrane emulsification is a fairly novel technique for preparation of various types of emulsions, which relies on the dispersed phase passing through a membrane in order to effect droplet formation. In this study, we have prepared polymeric nanoparticles of different morphologies using self-assembly of asymmetric block copolymers in connection with membrane emulsification. Shirasu Porous Glass (SPG) membranes has been employed as the membrane emulsification equipment, and poly (oligoethylene glycol acrylate)-block-poly (styrene) (POEGA-b-PSt) copolymers prepared via RAFT polymerization. It has been found that a number of different morphologies can be achieved using this novel technique, including spheres, rods, and vesicles. Interestingly, the results have shown that the morphology can be controlled not only by adjusting experimental parameters specific to the membrane emulsification step such as membrane pore size and pressure, but also by changing the nature of organic solvent. As such, this method provides a novel route to these interesting nanoobjects, with interesting prospects in terms of exercising morphology control without altering the nature of the block copolymer itself.

scholarly journals Mercury, Arsenic and Lead Removal by Air Gap Membrane Distillation: Experimental Study

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1574 ◽  
Author(s):  
Abdullah Alkhudhiri ◽  
Mohammed Hakami ◽  
Myrto-Panagiota Zacharof ◽  
Hosam Abu Homod ◽  
Ahmed Alsadun
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Removal Efficiency ◽  
Membrane Distillation ◽  
Air Gap ◽  
Lead Removal ◽  
Membrane Pore ◽  
Pore Sizes ◽  
Air Gap Membrane Distillation ◽  
Wide Range

Synthetic industrial wastewater samples containing mercury (Hg), arsenic (As), and lead (Pb) ions in various concentrations were prepared and treated by air gap membrane distillation (AGMD), a promising method for heavy metals removal. Three different membrane pore sizes (0.2, 0.45, and 1 μm) which are commercially available (TF200, TF450, and TF1000) were tested to assess their effectiveness in combination with various heavy metal concentrations and operating parameters (flow rate 1–5 L/min, feed temperature 40–70 °C, and pH 2–11). The results indicated that a high removal efficiency of the heavy metals was achieved by AGMD. TF200 and TF450 showed excellent membrane removal efficiency, which was above 96% for heavy metal ions in a wide range of concentrations. In addition, there was no significant influence of the pH value on the metal removal efficiency. Energy consumption was monitored at different membrane pore sizes and was found to be almost independent of membrane pore size and metal type.

scholarly journals An Efficient Method to Determine Membrane Molecular Weight Cut-Off Using Fluorescent Silica Nanoparticles

Membranes ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 271
Author(s):  
Mariam Fadel ◽  
Yvan Wyart ◽  
Philippe Moulin
Keyword(s):  
Molecular Weight ◽  
Silica Nanoparticles ◽  
Retention Rate ◽  
Transmembrane Pressure ◽  
Experimental Conditions ◽  
Membrane Pore ◽  
Fluorescent Silica Nanoparticles ◽  
Wide Range ◽  
Membrane Pore Size ◽  
Different Diameters

Membrane processes have revolutionized many industries because they are more energy and environmentally friendly than other separation techniques. This initial selection of the membrane for any application is based on its Molecular Weight Cut-Off (MWCO). However, there is a lack of a quantitative, liable, and rapid method to determine the MWCO of the membrane. In this study, a methodology to determine the MWCO, based on the retention of fluorescent silica nanoparticles (NPs), is presented. Optimized experimental conditions (Transmembrane pressure, filtration duration, suspension concentration, etc.) have been performed on different membranes MWCO. Filtrations with suspension of fluorescent NPs of different diameters 70, 100, 200 and 300 nm have been examined. The NPs sizes were selected to cover a wide range in order to study NPs diameters larger, close to, and smaller than the membrane pore size. A particle tracking analysis with a nanosight allows us to calculate the retention curves at all times. The retention rate curves were shifted over the filtration process at different times due to the fouling. The mechanism of fouling of the retained NPs explains the determined value of the MWCO. The reliability of this methodology, which presents a rapid quantitative way to determine the MWCO, is in good agreement with the value given by the manufacturer. In addition, this methodology gives access to the retention curve and makes it possible to determine the MWCO as a function of the desired retention rate.

Comparative study of polyvinylidene fluoride and PES flat membranes in submerged MBRs to treat domestic wastewater

2009 ◽  
Vol 59 (3) ◽  
pp. 399-405 ◽  
Author(s):  
T. Zhu ◽  
Y. H. Xie ◽  
J. Jiang ◽  
Y. T. Wang ◽  
H. J. Zhang ◽  
...  
Keyword(s):  
Polyvinylidene Fluoride ◽  
Domestic Wastewater ◽  
Membrane Bioreactors ◽  
Membrane Pore ◽  
Pvdf Membrane ◽  
Membrane Flux ◽  
Removal Efficiencies ◽  
Membrane Pore Size ◽  
Pes Membrane ◽  
Flat Membranes

Two kinds of membranes, polyvinylidene fluoride (PVDF) and polyethersulfone (PES), were used in submerged flat membrane bioreactors (MBRs) to treat domestic wastewater in this study. The MBRs ran under the same reactor structure, the same membrane pore size of 0.45 μm and the same anoxic/ oxic (A/O) process. The experimental results showed that: (1) With the influent of BOD5 200–500 mg/L and CODCr 400–1,000 mg/L, PVDF MBR achieved the removal efficiencies of BOD5 96–98% and CODCr 89–98%, and those were 97–99% and 93–97% in PES MBR. The interceptive efficiency of PES membrane to BOD5 and CODCr was superior to PVDF membrane. (2) The removal efficiencies of TN and NH3-N in two MBRs exhibited good results which were greater than 85%. The removal efficiencies of TP were greater than 80% in both MBRs. (3) MLSS concentration changed from 2,000 mg/L to 7,000 mg/L during the experiment. PES membrane was not washed and the membrane flux was steady. However, the flux of PVDF one decreased quickly and was washed for twice. It meant that PES membrane had fine capability than PVDF one.

scholarly journals Influence of Membrane Properties on Pineapple Wine Clarification and Fouling Behavior

2017 ◽  
Vol 1 (1) ◽  
Author(s):  
W. Youravong ◽  
M. Phukdeekhong ◽  
P. Taksinpatanapong
Keyword(s):  
Pore Size ◽  
Membrane Fouling ◽  
Polyvinylidene Fluoride ◽  
Pilot Scale ◽  
Membrane Properties ◽  
Permeate Flux ◽  
Membrane Pore ◽  
Dead End ◽  
Membrane Pore Size ◽  
Stirred Cell

The experiment was carried out to investigate the influence of membrane pore size and hydrophobicity on the quality of clarified pineapple wine and fouling characteristics, using stirred cell dead–end microfiltration. The test membranes were mixed cellulose acetate (MCE, pore size 0.45 and 0.22 μm), modified polyvinylidene fluoride (MPVDF, 0.22 μm) and polyethersulfone (PESF, 0.22 μm). It was found that all types of membrane successfully clarified the pineapple wine. The membrane pore size and hydrophobicity played an importance role in membrane fouling, both reversible and irreversible. Regarding the permeate flux and fouling, 0.45 μm MCE was the most suitable for pineapple wine clarification. However, intensive organoleptic test with pilot scale would be needed.

scholarly journals Mechanism investigation of virus removal in a membrane bioreactor

2006 ◽  
Vol 6 (6) ◽  
pp. 51-59 ◽  
Author(s):  
X. Zheng ◽  
J.X. Liu
Keyword(s):  
Membrane Bioreactor ◽  
Membrane Surface ◽  
Membrane Pore ◽  
Virus Removal ◽  
Pore Sizes ◽  
Pathogenic Viruses ◽  
Mean Size ◽  
Membrane Modules ◽  
Membrane Pore Size ◽  
Model Virus

Virus removal in a membrane bioreactor (MBR) by gravity drain was studied. Coliphage f2 (mean size of 25 nm), which is similar in size to human enteric pathogenic viruses, was selected as a model virus. Two microfiltration membrane modules with pore sizes of 0.22 μm and 0.1 μm were applied to investigate the effects of membrane pore size on the virus rejection. The MBR with these modules could reject virus in a range of 2.6–5.1 logs. The experimental results showed that the mechanisms of virus removal in the MBR involved rejection and inactivation. The virus rejection depended mainly on the dynamic layer on the membrane surface (not membrane itself) because virus rejection by the membrane modules with pore sizes of 0.1 μm and 0.22 μm were similar. The microbial activity and the aeration oxidation were the two important factors for the virus inactivation. It was found that the inactivation of coliphage f2 was much more rapidly in activated sludge mixed liquor than in clean water, and the effect of aeration was significant.

scholarly journals The Evolution of the Bacterial Community Between Hospitals, Wastewater Treatment Plants and the Aquatic Environment

2020 ◽  
Vol 71 (4) ◽  
pp. 313-316
Author(s):  
Alina Roxana Banciu ◽  
Lucian Ionescu ◽  
Daniela Liliana Ionica ◽  
Monica Alexandra Vaideanu ◽  
Simona Mariana Calinescu ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Surface Water ◽  
Fecal Coliform ◽  
Wastewater Treatment Plants ◽  
Fecal Coliforms ◽  
Coliform Bacteria ◽  
Treatment Processes ◽  
Rural And Urban ◽  
Hospital Effluents ◽  
The Impact

Wastewater treatment plants are major interface between rural and urban activities and the natural environment with problems relating to the survival and transmission of the fecal bacteria into streams and rivers. The main goal of this paper was to showed the impact of WWTPs on fecal populations bacteria and their dissemination into the aquatic ecosystems. The sampling campaigns were conducted in 2019 where the hospital and WWTPs wastewater from three cities from the south-eastern part of Romania and the surface water of their emissaries were trimestral collected. The quantitative and qualitative analysis of total and fecal coliforms indicated the efficiency of wastewater treatment processes but at the same time, the contribution of contamination with hospital effluents has been demonstrated. Also, the microbiological results showed the selectivity of the destruction of fecal coliform bacteria between wastewater and surface water.

Comparative Assessment of Membrane Fouling Propensity Using Colloidal Silica as Foulant

2012 ◽  
Vol 209-211 ◽  
pp. 1995-1998 ◽  
Author(s):  
Chai Hoon Koo ◽  
Abdul Wahab Mohammad ◽  
Fatihah Suja' ◽  
Meor Zainal Meor Talib
Keyword(s):  
Membrane Fouling ◽  
Polyvinylidene Fluoride ◽  
Colloidal Silica ◽  
Crossflow Filtration ◽  
Membrane Pore ◽  
Dead End ◽  
Silica Suspension ◽  
Index Tests ◽  
Membrane Pore Size ◽  
Modified Fouling Index

Other than silt density index (SDI), modified fouling index (MFI) is claimed as one of most useful fouling predictive tools in the practice of reverse osmosis. In this study, the effect of colloidal silica particles on the MFI value with the presence of crossflow sampler (CFS) cell at the upstream of MFI setup was systematically investigated. Colloidal silica with the particle size ranging from 70-100 nm was used as the model foulant in this experiment. The feed silica suspension was 0, 50, and 200 mg/L. The effect of membrane pore size as the test membrane in the dead-end cell on the fouling indices was also studied. Polyvinylidene fluoride (PVDF) membranes with molecular weight cut-offs of 150 and 100 kDa were employed. As predicted, the experiment results demonstrated that the fouling indices increased significantly as the feed silica concentration increased. The CFS-MFI values were always lower than the MFI in all the fouling index tests due to the shear force effect generated under the crossflow filtration mode. The fouling index generated from PVDF100 was higher than that of PVDF150 due to the retention of smaller particles. For this reason, PVDF100 membrane was preferred to be used as the test membrane for fouling index tests using colloidal silica over the PVDF150.

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