Hybrid TiO2 photocatalytic oxidation and ultrafiltration for humic acid removal and membrane fouling control

2011 ◽  
Vol 11 (3) ◽  
pp. 324-332 ◽  
Author(s):  
Hongwei Bai ◽  
Darren Delai Sun
Keyword(s):  
Humic Acid ◽  
Membrane Fouling ◽  
Photocatalytic Oxidation ◽  
Removal Rate ◽  
Optimal Choice ◽  
Feed Water ◽  
Permeate Flux ◽  
Hydrophobic Membrane ◽  
Fouling Control ◽  
And Control

Hybrid UV/TiO2 photocatalytic oxidation (PCO) and ultrafiltration (UF) process (PCO-UF) were used to remove humic acid (HA) and control membrane fouling. The PCO-UF process showed advantages in terms of higher removal rate of HA, higher permeate flux and less membrane fouling over UF alone and PCO alone on HA removal and membrane fouling control. Membrane material and pH of feed water were shown to be the influence on the performance of PCO-UF process. It was observed that higher pH of HA feed water and a hydrophobic membrane lead to better removal of HA with relatively higher permeate flux. The experimental results in this study demonstrated that 100 kDa ultraflic UF membrane and pH 9 of HA feed water would be the optimal choice for HA removal in the combined PCO-UF process.

scholarly journals Membrane Fouling in Algal Separation Processes: A Review of Influencing Factors and Mechanisms

2021 ◽  
Vol 3 ◽  
Author(s):  
Andres Felipe Novoa ◽  
Johannes S. Vrouwenvelder ◽  
Luca Fortunato
Keyword(s):  
Membrane Fouling ◽  
Control Strategies ◽  
Membrane Surface ◽  
Cost Effective ◽  
Dynamic Responses ◽  
Feed Water ◽  
Operational Conditions ◽  
Term Operation ◽  
Fouling Control ◽  
And Control

The use of algal biotechnologies in the production of biofuels, food, and valuable products has gained momentum in recent years, owing to its distinctive rapid growth and compatibility to be coupled to wastewater treatment in membrane photobioreactors. However, membrane fouling is considered a main drawback that offsets the benefits of algal applications by heavily impacting the operation cost. Several fouling control strategies have been proposed, addressing aspects related to characteristics in the feed water and membranes, operational conditions, and biomass properties. However, the lack of understanding of the mechanisms behind algal biofouling and control challenges the development of cost-effective strategies needed for the long-term operation of membrane photobioreactors. This paper reviews the progress on algal membrane fouling and control strategies. Herein, we summarize information in the composition and characteristics of algal foulants, namely algal organic matter, cells, and transparent exopolymer particles; and review their dynamic responses to modifications in the feedwater, membrane surface, hydrodynamics, and cleaning methods. This review comparatively analyzes (i) efficiency in fouling control or mitigation, (ii) advantages and drawbacks, (iii) technological performance, and (iv) challenges and knowledge gaps. Ultimately, the article provides a primary reference of algal biofouling in membrane-based applications.

A study on the fouling phenomena of a microfiltration membrane

2004 ◽  
Vol 4 (5-6) ◽  
pp. 223-231
Author(s):  
H.-H. Yeh ◽  
W.-H. Wang
Keyword(s):  
Salicylic Acid ◽  
Humic Acid ◽  
Calcium Ion ◽  
Colloidal Particles ◽  
Alginic Acid ◽  
Particle System ◽  
Feed Water ◽  
Permeate Flux ◽  
Widespread Application ◽  
Latex Beads

The utilization of membrane processes for drinking water treatment has become more popular. However, fouling by source water probably is the major factor prohibits its widespread application. In this research, the fouling phenomena of a microfiltration (MF) membrane were studied. The interactions among colloidal particles, calcium ion, and dissolved organics, such as salicylic acid, humic acid, and alginic acid, on MF fouling were focused. A lab-scale single hollow fiber MF membrane, made of polyvinylidenefluoride (PVDF), module was used. The results show that, for single organic compound, the extent of fouling caused by humic acid was higher that of alginic acid. For the latter, the permeate flux decrease at lower pH was more significant than those at higher pH. For low MW salicylic acid, both rejection and flux decrease were minor. It seems that solubility have strong correlation with fouling rate. The higher the solubility is, the lower the fouling rate. For sole colloidal particle system, latex beads with diameter close to the pore size of MF membrane showed severe fouling. Adding Ca can aggregate the latex beads, and alleviate fouling. However, calcium ion also found to increase fouling of alginic acid on membrane under neutral or alkali pH condition, probably via charge neutralization and/or bridging. In conclusion, MF fouling seems to be strongly related to the type of organics, size of colloidal particles, and the existence of divalent ions, in the feed water.

Characteristics of coagulation-flocculation of humic acid with effective performance of polymeric flocculant and inorganic coagulant

2003 ◽  
Vol 47 (1) ◽  
pp. 89-95 ◽  
Author(s):  
J. Yu ◽  
D.D. Sun ◽  
J.H. Tay
Keyword(s):  
Humic Acid ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Molecular Size ◽  
Aluminium Sulphate ◽  
Fouling Control ◽  
Effective Performance ◽  
Water And Wastewater ◽  
Pre Treatment ◽  
Flocculation Process

Ferric chloride and aluminium sulphate as coagulants and positive charged flocculants PDDMAC ((PDDMAC = poly (diallyldimethylammonium chloride) were used for pre-treatment of water and wastewater for removing humic substance prior to RO membrane filtration. It was found that a combination of flocculant and coagulant enhanced the coagulation-flocculation process and humic acid removal. The optimum conditions of coagulation-flocculation were established in reference to the ratio of humic acid and coagulant. Zeta potential and the ratio of E4/E6 were investigated to explore the possible micro-mechanisms of coagulation-flocculation. The ratios of E4/E6 show the molecular size variations using different coagulants and flocculants, which are expected to benefit membrane-fouling control.

Influence of humic acid on the long-term performance of direct contact membrane distillation

2018 ◽  
Vol 30 (1) ◽  
pp. 109-120 ◽  
Author(s):  
Dong-Wan Cho ◽  
Gihoon Kwon ◽  
Jeongmin Han ◽  
Hocheol Song
Keyword(s):  
Humic Acid ◽  
Membrane Fouling ◽  
Coalbed Methane ◽  
Direct Contact ◽  
Membrane Surface ◽  
Membrane Distillation ◽  
Permeate Flux ◽  
Direct Contact Membrane Distillation ◽  
High Level

In this study, the influence of humic acid on the treatment of coalbed methane water by direct contact membrane distillation was examined with bench-scale test unit. During short-term distillation (1000 min), high level of humic acid above 50 ppm resulted in significant decrease in permeate flux, while low level of humic acid (∼2 ppm) had little influence on the flux. For the long-term distillation (5000 min), the flux decline began at 3400 min in the presence of 5 ppm humic acid and 5 mM Ca2+, and decreased to ∼40% of initial flux at 5000 min. The spectroscopic analysis of the membrane used revealed that the surface was covered by hydrophilic layers mainly composed of calcite. The membrane fouling effect of humic acid became more significant in the presence of Ca2+ due to more facile calcite formation on the membrane surface. It was demonstrated that humic acid enhanced CaCO3 deposition on the membrane surfaces, thereby expediting the scaling phenomenon.

Interactions of hypochlorite ion and humic acid: photolytic and photocatalytic pathways

2001 ◽  
Vol 44 (5) ◽  
pp. 205-210 ◽  
Author(s):  
D. Gonenç ◽  
M. Bekbolet
Keyword(s):  
Humic Acid ◽  
Reaction Kinetics ◽  
Removal Efficiency ◽  
Photocatalytic Oxidation ◽  
Removal Rate ◽  
Order Reaction ◽  
First Order Reaction ◽  
Acid Oxidation ◽  
First Order ◽  
Toc Removal

Photolytic and photocatalytic interactions of hypochlorite ion and humic acid are investigated under various conditions. Humic acid oxidation by aqueous chlorine under dark conditions are expressed in terms of first order reaction kinetics. Upon irradiation (300 nm < λ < 400 nm), photolysis of aqueous chlorine affect the removal efficiency of humic acid via oxidation. TiO2 sensitised photocatalytic oxidation conditions reveal an increase in the TOC removal rate of humic acid in the presence of aqueous chlorine. Under the specified conditions, increasing the photocatalyst loading up to 1.0 mg/mL markedly increase the TOC removal rate.

Nanofiltration membrane fouling by conventionally treated surface water

2003 ◽  
Vol 3 (5-6) ◽  
pp. 183-190
Author(s):  
R. Liikanen ◽  
H. Kiuru ◽  
T. Tuhkanen ◽  
M. Nyström
Keyword(s):  
Water Treatment ◽  
Surface Water ◽  
Membrane Fouling ◽  
Feed Water ◽  
Water Characteristics ◽  
Treatment Train ◽  
Water Constituents ◽  
Filtration Unit ◽  
And Control ◽  
Chemical Water

Nanofiltration is a very effective technique for improving the removal of trace organics after a conventional chemical water treatment train. However, the fouling of the membranes decreases the applicability of the process, and thus, an understanding and control of membrane fouling are crucial for a more widespread use of nanofiltration in water treatment. The fouling of different nanofiltration membranes by pre-treated surface waters was investigated in a laboratory-scale filtration unit in this study. The results indicate that the traditional chemical treatment does not remove membrane foulants from the surface water. No correlation was found between the feed water constituents and nanofiltration performance, but most feed water components are expected to interact in membrane fouling. Actually, the performance of the nanofiltration process was more related to membrane than to feed water characteristics.

Critical design considerations for harnessing reverse osmosis processes in water/wastewater treatment

2006 ◽  
Vol 6 (6) ◽  
pp. 61-70 ◽  
Author(s):  
L.F. Song ◽  
K.G. Tay ◽  
G. Singh
Keyword(s):  
Mass Transfer ◽  
Membrane Fouling ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Full Scale ◽  
Driving Pressure ◽  
Feed Water ◽  
Permeate Flux ◽  
Membrane Channel ◽  
Permeable Membrane

In this paper, the performance of the full-scale RO process with highly permeable membranes and the governing mechanisms were carefully studied. It was found that the performance of a full-scale RO process could be controlled by two possible mechanisms, namely mass transfer rate and thermodynamic limitations. Under relatively low driving pressure, it was controlled by mass transfer rate (water flux) of the membrane. However, with the highly permeable membrane, it is possible that the performance is limited by the thermodynamic limitation, in which the osmotic pressure becomes equal to the driving pressure inside of the membrane channel. A process controlled by thermodynamic limitation is an extremely case of the hydraulic imbalance problem. When it occurs, it means part of the membranes in the processes do not contribute to permeate production. More complicated are situations in the intermediate pressure range, in which both mechanisms contribute to, but none of them can dominate, the performance of the process. Some innovative concepts and theories on the performance of the full-scale RO processes were developed. These concepts and theories may provide better qualitative explanations for the behaviors often observed in the full-scale RO processes. A better quantitative simulations or predictions of the performance of the process were developed upon these concepts and theories. Experiments were carried out on a pilot membrane process of 6 m membrane channel to imitate the performance of the full-scale RO under various conditions. The experimental performance data were compared with theoretical simulations and excellent agreement was obtained. Another focus of this current study was on characterization and modeling of membrane fouling in the full-scale RO process. Colloidal fouling experiments were conducted to study the fouling potential of feed water and a new fouling indicator was proposed. The indicator can be directly used in the mathematical model to simulate fouling development in the full-scale RO processes. Model simulations showed that under certain condition (thermodynamic restriction), the recovery or average permeate flux of a full-scale RO process would maintain a constant value even membrane fouling was taking place. Experimental verification of the simulation results is currently under way. With the new developments and findings in this area, methods or protocols for optimization of full-scale processes of the highly permeable RO membranes were suggested.

Chemical pretreatment of feed water for membrane distillation

2008 ◽  
Vol 62 (1) ◽  
Author(s):  
Marek Gryta
Keyword(s):  
Membrane Fouling ◽  
Membrane Surface ◽  
Membrane Distillation ◽  
Feed Water ◽  
Chemical Pretreatment ◽  
Permeate Flux ◽  
Membrane Scaling ◽  
Water Pretreatment ◽  
Energy Dispersion Spectrometry ◽  
Process Operation

AbstractMembrane distillation was used to produce demineralized water from ground water. The influence of feed water pretreatment carried out in a contact clarifier (softening with Ca(OH)2 and coagulation with FeSO4 · 7H2O) followed by filtration, on the process effectiveness was evaluated. It was found that the chemical pretreatment decreased the membrane fouling; however, the degree of water purification was insufficient because precipitation of small amounts of deposit on the membrane surface during the process operation was still observed. The permeate flux was gradually decreasing as a result of scaling. The morphology and composition of the fouling layer were studied using scanning electron microscopy coupled with energy dispersion spectrometry. The presence of significant amounts of silica, apart from calcium and magnesium, was determined in the formed deposit. The removal of foulants by heterogeneous crystallization performed inside the filter (70 mesh), assembled directly at the module inlet, was found to be a solution preventing the membrane scaling.

scholarly journals Performances of air gap and water gap MD desalination modules

2018 ◽  
Vol 13 (1) ◽  
pp. 200-209 ◽  
Author(s):  
Atia E. Khalifa
Keyword(s):  
Specific Energy Consumption ◽  
Membrane Distillation ◽  
Air Gap ◽  
Dominant Factor ◽  
Feed Water ◽  
Permeate Flux ◽  
Hydrophobic Membrane ◽  
Air Gap Membrane Distillation ◽  
Gap Width ◽  
Feed Temperature

Abstract Membrane distillation (MD) is a promising thermally-driven membrane separation technology for water desalination. In MD, water vapor is being separated from the hot feed water solution using a micro-porous hydrophobic membrane, due to the difference in vapor pressures across the membrane. In the present work, experiments are conducted to compare the performance of water gap membrane distillation (WGMD) and air gap membrane distillation (AGMD) modules under the main operating and design conditions including the feed and coolant temperatures, membrane material and pore sizes, and the gap width. Results showed that the WGMD module produced higher fluxes as compared to the AGMD module, for all test conditions. The feed temperature is the dominant factor affecting the system flux. The permeate flux increases with reducing the gap width for both water and air gap modules. However, WGMD module was found to be less sensitive to the change in the gap width compared to the AGMD module. The PTFE membrane produced higher permeate flux as compared to the PVDF membrane. Bigger mean pore diameter enhanced the permeate flux, however, this enhancement is marginal at high feed temperatures. With increasing the feed temperature, the GOR values increase and the specific energy consumption decreases.

Production of process water using integrated membrane processes

2006 ◽  
Vol 60 (6) ◽  
Author(s):  
K. Karakulski ◽  
M. Gryta ◽  
M. Sasim
Keyword(s):  
Reverse Osmosis ◽  
Membrane Fouling ◽  
Tap Water ◽  
Industrial Effluents ◽  
Membrane Distillation ◽  
Process Water ◽  
Feed Water ◽  
Reverse Osmosis Membrane ◽  
Permeate Flux ◽  
Membrane Processes

AbstractApplication of ultrafiltration, nanofiltration, reverse osmosis, membrane distillation, and integrated membrane processes for the preparation of process water from natural water or industrial effluents was investigated. A two-stage reverse osmosis plant enabled almost complete removal of solutes from the feed water. High-purity water was prepared using the membrane distillation. However, during this process a rapid membrane fouling and permeate flux decline was observed when the tap water was used as a feed. The precipitation of deposit in the modules was limited by the separation of sparingly soluble salts from the feed water in the nanofiltration. The combined reverse osmosis—membrane distillation process prevented the formation of salt deposits on the membranes employed for the membrane distillation. Ultrafiltration was found to be very effective removing trace amounts of oil from the feed water. Then the ultrafiltration permeate was used for feeding of the remaining membrane modules resulting in the total removal of oil residue contamination. The ultrafiltration allowed producing process water directly from the industrial effluents containing petroleum derivatives.

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