jmst
Abstract : The Performance of Hybrid Anaerobic Membrane Bioreactors (AnMBRs) Added with Powdered Activated Carbon (PAC) Based on Different Sludge Retention Times
|
|
Abstract: In this study, the effects of different sludge retention times (SRTs) on membrane fouling control with the addition of powdered activated carbon (PAC) were investigated for the anaerobic membrane bioreactors (AnMBRs). Chemical oxygen demand (COD), mixed liquor volatile suspended solids (MLVSS), food to microorganisms (F/M) ratio, particle size distribution, extracellular polymeric substances (EPS) and their relationships with membrane fouling were studied for AnMBR added with PAC at different SRTs. As SRT of the AnMBR increased to higher days, MLVSS concentration would increase and F/M ratio decreased and it was found to have a better membrane fouling control. It was also noticed that PAC addition would decrease EPS concentration and increased the floc size of the biomass which would help to reduce membrane fouling rate of AnMBRs. Keywords: Palm Oil Mill Effluent (POME), Anaerobic membrane bioreactor (AnMBR), membrane fouling, powdered activated carbon (PAC), sludge retention times (SRTs), F/M ratio. Download Full Article |
Abstract : Synthesis and Characterization of Nanocomposite Hydroxy-Sodalite/Ceramic Membrane via Pore-Plugging Hydrothermal Synthesis Technique
|
|
Abstract: In this article, synthesis and characterization of nanocomposite hydroxy sodalite (H-SOD)/α-alumina membrane via the so-called “pore-plugging” hydrothermal synthesis (PPH) protocol is reported for the first time. In nanocomposite architecture membranes, zeolite crystals are embedded within the pores of the supports instead of forming thin-film layers of the zeolite crystals on the surface of the supports. The as-prepared membranes were characterized with SEM and FTIR for morphology and purity of the H-SOD crystals. Compared to the conventional in-situ direct hydrothermal synthesis, membranes obtained from PPH possess higher mechanical and thermal stability. In addition, defect control with nanocomposite architecture membrane is possible because the zeolite crystals are embedded within the support pores of the membrane, thereby limiting the maximum defect size to the pore sizes of support. The nanocomposite architecture nature of the membranes safeguards the membrane from shocks or abrasion that could promote defects/inter-crystalline pores formation. These advantages could be helpful in the scale-up process of the preparation procedure of membranes at the commercial level with less-demanding conditions. Keywords: Hydroxy sodalite, Nanocomposites, Membranes, Ceramics, Porous materials, Thin films.Download Full Article |
Abstract : A Novel Approach to Synthesize Helix Wave Hollow Fiber Membranes for Separation Applications
|
|
Abstract: Helix wave hollow fiber membranes are promising candidate to mitigate fouling and polarization effects in membrane operations. Current study describes a novel but simple approach to synthesize hollow fiber membranes with helix wave configuration. Poly(ether sulfone) (PES) based helix-waved hollow fiber membranes have been fabricated by dry-wet phase inversion process by using asymmetric coagulation conditions. Frequencies of the wave cycle have been observed approximately 20 and the wave length 7.1-7.6mm under the specifically required operating conditions defined by dope solution extrudate rate of 1g/min through 4cm of air-gap heights with 8.6m/min of winding speeds. On the other hand, simple hollow fibers are formed when the elongation force exerted by the winder is much higher than the surface tension of the external coagulant. The process can be useful for making polymer fibers for other applications as well. Keywords: Helix wave, hollow fiber membranes, poly (ether sulfone), asymmetric coagulation.Download Full Article |
Abstract : Control of Membrane Surface Roughness and Pattern Wave Length by Changing the Nonsolvent (Water) Influx Rate
|
|
Abstract: The control of surface roughness of polyvinylidene fluoride (PVDF), polyethersulfone (PES), polysulfone (PS) and cellulose (CE) membranes was attempted by changing the rate of nonsolvent influx in the phase inversion process. PVDF and CE were chosen to represent membranes of high hydrophobicity and hydrophilicity, respectively, while PES and PS were chosen to represent membranes of intermediate hydrophobicity/-philicity. The concentration of sodium chloride (NaCl) in the aqueous coagulation medium was increased from 0 to 1.9 mol/L to decrease the rate of nonsolvent (water) influx in the solvent/nonsolvent exchange process. As well, the effect of polymer concentration and solvent on the surface roughness was investigated with respect to PVDF and PES. It was observed that the membrane surface roughness increased and decreased, respectively, for the hydrophobic PVDF and hydrophilic CE membrane as the rate of nonsolvent influx was decreased. For the PES and PS membranes of intermediate hydrophilic/-philicity, no significant roughness change was observed. The surface roughness tended to increase as the solution viscosity decreased. It was also observed that the pattern wave length of the hydrophobic membrane did not change significantly while that of the hydrophilic membrane increased significantly as the solvent influx rate was reduced. This trend is predictable by considering the shrinking or swelling of the cast polymer solution during the solvent/nonsolvent exchange process. Keywords: Surface roughness, pattern wave length, hydrophobicity/-philicity, AFM, nonsolvent influx rate, membrane..Download Full Article |
