scholarly journals Ozone Chemically Enhanced Backwash for Ceramic Membrane Fouling Control in Cyanobacteria-Laden Water

Membranes ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 213
Author(s):  
Stéphane Venne ◽  
Onita D. Basu ◽  
Benoit Barbeau
Keyword(s):  
Surface Water ◽  
Surface Waters ◽  
Membrane Fouling ◽  
Ceramic Membrane ◽  
Membrane Surface ◽  
Operating Costs ◽  
Fouling Control ◽  
Dead End ◽  
Cake Layer ◽  
Flow Experiments

Membrane fouling in surface waters impacted by cyanobacteria is currently poorly controlled and results in high operating costs. A chemically enhanced backwash (CEB) is one possible strategy to mitigate cyanobacteria fouling. This research investigates the potential of using an ozone CEB to control the fouling caused by Microcystis aeruginosa in filtered surface water on a ceramic ultrafiltration membrane. Batch ozonation tests and dead-end, continuous flow experiments were conducted with ozone doses between 0 and 19 mg O3/mg carbon. In all tests, the ozone was shown to react more rapidly with the filtered surface water foulants than with cyanobacteria. In addition, the ozone CEB demonstrated an improved mitigation of irreversible fouling over 2 cycles versus a single CEB cycle; indicating that the ozone CEB functioned better as the cake layer developed. Ozone likely weakens the compressible cake layer formed by cyanobacteria on the membrane surface during filtration, which then becomes more hydraulically reversible. In fact, the ozone CEB reduced the fouling resistance by 35% more than the hydraulic backwash when the cake was more compressed.

Exerting ultrasound to control the membrane fouling in filtration of anaerobic activated sludge—mechanism and membrane damage

2008 ◽  
Vol 57 (5) ◽  
pp. 773-779 ◽  
Author(s):  
Xianghua Wen ◽  
Pengzhe Sui ◽  
Xia Huang
Keyword(s):  
Activated Sludge ◽  
Hydroxyl Radicals ◽  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Chemical Interaction ◽  
Membrane Surface ◽  
Membrane Damage ◽  
Operational Conditions ◽  
Fouling Control ◽  
Cake Layer

In this study, ultrasound was applied to control membrane fouling development online in an anaerobic membrane bioreactor (AMBR). Experimental results showed that membrane fouling could be controlled effectively by ultrasound although membrane damage may occur under some operational conditions. Based upon the observation on the damaged membrane surface via SEM, two mechanisms causing membrane damage by exerting ultrasound are inferred as micro particle collide on the membrane surface and chemical interaction between membrane materials and hydroxyl radicals produced by acoustic cavitations. Not only membrane damage but also membrane fouling control and membrane fouling cleaning were resulted from these mechanisms. Properly selecting ultrasonic intensity and working time, and keeping a certain thickness of cake layer on membrane surface could be effective ways to protect membrane against damage.

scholarly journals Fouling Mechanisms Analysis via Combined Fouling Models for Surface Water Ultrafiltration Process

Membranes ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 149 ◽  
Author(s):  
Bin Huang ◽  
Hangkun Gu ◽  
Kang Xiao ◽  
Fangshu Qu ◽  
Huarong Yu ◽  
...  
Keyword(s):  
Water Treatment ◽  
Surface Water ◽  
Membrane Fouling ◽  
Mechanism Analysis ◽  
Surface Water Treatment ◽  
Dead End ◽  
Cake Layer ◽  
Significant Difference ◽  
Combined Models ◽  
And Control

Membrane fouling is still the bottleneck affecting the technical and economic performance of the ultrafiltration (UF) process for the surface water treatment. It is very important to accurately understand fouling mechanisms to effectively prevent and control UF fouling. The rejection performance and fouling mechanisms of the UF membrane for raw and coagulated surface water treatment were investigated under the cycle operation of constant-pressure dead-end filtration and backwash. There was no significant difference in the UF permeate quality of raw and coagulated surface water. Coagulation mainly removed substances causing turbidity in raw surface water (including most suspended particles and a few organic colloids) and thus mitigated UF fouling effectively. Backwash showed limited fouling removal. For the UF process of both raw and coagulated surface water, the fittings using single models showed good linearity for multiple models mainly due to statistical illusions, while the fittings using combined models showed that only the combined complete blocking and cake layer model fitted well. The quantitative calculations showed that complete blocking was the main reason causing flux decline. Membrane fouling mechanism analysis based on combined models could provide theoretical supports to prevent and control UF fouling for surface water treatment.

Integration of ceramic membrane and compressed air-assisted solvent extraction (CASX) for metal recovery

2010 ◽  
Vol 62 (6) ◽  
pp. 1274-1280 ◽  
Author(s):  
Chi-Wang Li ◽  
Chun-Hao Chiu ◽  
Yu-Cheng Lee ◽  
Chia-Hao Chang ◽  
Yu-Hsun Lee ◽  
...  
Keyword(s):  
Solvent Extraction ◽  
Removal Efficiency ◽  
Membrane Fouling ◽  
Water Solubility ◽  
Ceramic Membrane ◽  
Metal Removal ◽  
Membrane Surface ◽  
Extraction Process ◽  
Compressed Air ◽  
Dead End

In our previous publications, compressed air-assisted solvent extraction process (CASX) was developed and proved to be kinetically efficient process for metal removal. In the current study, CASX with a ceramic MF membrane integrated for separation of spent solvent was employed to remove and recover metal from wastewater. MF was operated either in crossflow mode or dead-end with intermittent flushing mode. Under crossflow mode, three distinct stages of flux vs. TMP (trans-membrane pressure) relationship were observed. In the first stage, flux increases with increasing TMP which is followed by the stage of stable flux with increasing TMP. After reaching a threshold TMP which is dependent of crossflow velocity, flux increases again with increasing TMP. At the last stage, solvent was pushed through membrane pores as indicated by increasing permeate COD. In dead-end with intermittent flushing mode, an intermittent flushing flow (2 min after a 10-min or a 30-min dead-end filtration) was incorporated to reduce membrane fouling by flush out MSAB accumulated on membrane surface. Effects of solvent concentration and composition were also investigated. Solvent concentrations ranging from 0.1 to 1% (w/w) have no adverse effect in terms of membrane fouling. However, solvent composition, i.e. D2EHPA/kerosene ratio, shows impact on membrane fouling. The type of metal extractants employed in CASX has significant impact on both membrane fouling and the quality of filtrate due to the differences in their viscosity and water solubility. Separation of MSAB was the limiting process controlling metal removal efficiency, and the removal efficiency of Cd(II) and Cr(VI) followed the same trend as that for COD.

Description of different effects of in-line coagulation upon semi-dead-end ultrafiltration

2003 ◽  
Vol 3 (5-6) ◽  
pp. 337-344 ◽  
Author(s):  
W. Doyen ◽  
R. Vandaele ◽  
B. Molenberghs ◽  
J. Cromphout ◽  
P. Bielen ◽  
...  
Keyword(s):  
Surface Water ◽  
Membrane Surface ◽  
Environmental Scanning Electron Microscopy ◽  
High Volume ◽  
High Water ◽  
Transmembrane Pressure ◽  
Water Recovery ◽  
Dead End ◽  
Cake Layer ◽  
Cake Porosity

This paper describes the results of research focussed on the different effects of in-line coagulation (FeCl3), towards the operation of semi-dead-end UF for drinking water and process water production starting from surface water. In this research, firstly the effects of the use of FeCl3 on the formed cake were studied, by both direct and indirect measurements. Using the ESEM technique (environmental scanning electron microscopy), which enables one to make pictures of wet samples, we observed that cake thickness was much higher upon use of FeCl3 (20 instead of 2 μm). As a result, the cake porosity was calculated to be much higher with than without coagulant use (93% instead of 37%). From the stability (nonincreasing) of the starting transmembrane pressure (TMP) in the successive filtration cycles, upon semidead-end operation, it was concluded that cake layer was less prone to adhere to the membrane surface when using coagulant. This is even more emphasized once the dosing is stopped, as a consequence the TMP rises very steeply under difficult circumstances, such as; high flux rates, high water recovery rates, and the use of membranes made from polymers with high adsorption properties. Secondly, indirect effects of the use of coagulant on filtration behaviour were investigated. Thus, it was found that TMP increase in the filtration cycle was much lower, due to depth filtration in the formed high-volume cake, and TMP was much more stable over a long time. These observations were in good agreement with found higher cake porosity. Moreover, it was observed that due to the use of a coagulant, the influences of membrane polymer nature and membrane structure disappeared, cleaning action could be postponed and cleaning aggressiveness could be lowered. In addition, water recovery and flux rate could be increased, and influence of seasonal water quality variations could be better faced. Finally, it was found that the treatment of surface water with high DOC content (e.g. 10 mg DOC/l) was enabled.

Behavior of micro-particles in monolith ceramic membrane filtration with pre-coagulation

2004 ◽  
Vol 50 (12) ◽  
pp. 317-325 ◽  
Author(s):  
H. Yonekawa ◽  
Y. Tomita ◽  
Y. Watanabe
Keyword(s):  
Membrane Filtration ◽  
Ceramic Membrane ◽  
Membrane Surface ◽  
Flow Analysis ◽  
Ceramic Membranes ◽  
End Point ◽  
Micro Particles ◽  
Dead End ◽  
Cake Layer ◽  
The Dead

This paper is intended to clarify the characteristics unique to monolith ceramic membranes with pre-coagulation by referring to the behavior of micro-particles. Flow analysis and experiments have proved that monolith ceramic membranes show a unique flow pattern in the channels within the element, causing extremely rapid flocculation in the channel during dead-end filtration. It was assumed that charge-neutralized micro-particles concentrated near the membrane surface grow in size due to flocculation, and as a result, coarse micro-particles were taken up by the shearing force to flow out. As the dead end points of flow in all the channels are located near the end of the channels with higher filterability, most of the flocculated coarse particles are formed to a columnar cake intensively at the dead end point. Therefore cake layer forming on the membrane other than around the dead end point is alleviated. This behavior of particle flocculation and cake formation at the dead end point within the channels are unique characteristics of monolith ceramic membranes. This is why all monolith ceramic membrane water purification systems operating in Japan do not have pretreatment equipment for flocculation and sedimentation.

scholarly journals Investigation of membrane fouling mechanism of intracellular organic matter during ultrafiltration

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Weiwei Huang ◽  
Yuanhong Zhu ◽  
Bingzhi Dong ◽  
Weiwei Lv ◽  
Quan Yuan ◽  
...  
Keyword(s):  
Organic Matter ◽  
Chlorella Vulgaris ◽  
Membrane Fouling ◽  
Membrane Surface ◽  
Layer Formation ◽  
Fouling Control ◽  
Fouling Mechanism ◽  
Cake Layer ◽  
Severe Degree ◽  
Filtration Flux

AbstractThis study investigated the ultrafiltration (UF) membrane fouling mechanism of intracellular organic matter (IOM) from Chlorella vulgaris (CV) and Microcystis aeruginosa (MA). Both CV- and MA-IOM caused severe membrane fouling during UF; however, there were significant differences in the membrane fouling by these two materials. Neutral hydrophilic (N-HPI) compounds were the organics that caused the most severe membrane fouling during CV-IOM filtration, whereas the MA-IOM membrane fouling was induced by mainly hydrophobic (HPO) organics. From an analysis based on Derjaguin–Landau–Verwey–Overbeek theory, it was found that the interaction energy between the membrane and foulants in the later stage of filtration was the major factor determining the efficiency of filtration for both CV-IOM and MA-IOM. The TPI organics in CV-IOM fouled the membrane to a more severe degree during the initial filtration flux; however, when the membrane surface was covered with CV-IOM foulants, the N-HPI fraction of CV-IOM caused the most severe membrane fouling because its attractive energy with the membrane was the highest. For MA-IOM, regardless of the initial filtration flux or the late stage of filtration, the HPO organics fouled the membrane to the greatest extent. An analysis of modified filtration models revealed that cake layer formation played a more important role than other fouling mechanisms during the filtration of CV-IOM and MA-IOM. This study provides a significant understanding of the membrane fouling mechanism of IOM and is beneficial for developing some strategies for membrane fouling control when treating MA and CV algae-laden waters.

scholarly journals Effect of Pre-Oxidation on Coagulation/Ceramic Membrane Treatment of Yangtze River Water

Membranes ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 369
Author(s):  
Shengji Xia ◽  
Xinran Zhang ◽  
Yuanchen Zhao ◽  
Fibor J. Tan ◽  
Pan Li ◽  
...  
Keyword(s):  
Water Treatment ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Ceramic Membrane ◽  
Membrane Separation ◽  
Membrane System ◽  
Coagulation System ◽  
Fouling Control ◽  
Filtration System ◽  
Membrane Treatment

The membrane separation process is being widely used in water treatment. It is very important to control membrane fouling in the process of water treatment. This study was conducted to evaluate the efficiency of a pre-oxidation-coagulation flat ceramic membrane filtration process using different oxidant types and dosages in water treatment and membrane fouling control. The results showed that under suitable concentration conditions, the effect on membrane fouling control of a NaClO pre-oxidation combined with a coagulation/ceramic membrane system was better than that of an O3 system. The oxidation process changed the structure of pollutants, reduced the pollution load and enhanced the coagulation process in a pre-oxidation-coagulation system as well. The influence of the oxidant on the filtration system was related to its oxidizability and other characteristics. NaClO and O3 performed more efficiently than KMnO4. NaClO was more conducive to the removal of DOC, and O3 was more conducive to the removal of UV254.

scholarly journals Alleviation of Ultrafiltration Membrane Fouling by ClO2 Pre-Oxidation: Fouling Mechanism and Interface Characteristics

Membranes ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 78
Author(s):  
Bin Liu ◽  
Meng Wang ◽  
Kaihan Yang ◽  
Guangchao Li ◽  
Zhou Shi
Keyword(s):  
Natural Water ◽  
Membrane Fouling ◽  
Interaction Force ◽  
Interfacial Free Energy ◽  
Fouling Control ◽  
Membrane Flux ◽  
Flux Decline ◽  
Interface Characteristics ◽  
Cake Layer ◽  
Free Energy Analysis

In order to alleviate membrane fouling and improve removal efficiency, a series of pretreatment technologies were applied to the ultrafiltration process. In this study, ClO2 was used as a pre-oxidation strategy for the ultrafiltration (UF) process. Humic acid (HA), sodium alginate (SA), and bovine serum albumin (BSA) were used as three typical organic model foulants, and the mixture of the three substances was used as a representation of simulated natural water. The dosages of ClO2 were 0.5, 1, 2, 4, and 8 mg/L, with 90 min pre-oxidation. The results showed that ClO2 pre-oxidation at low doses (1–2 mg/L) could alleviate the membrane flux decline caused by humus, polysaccharides, and simulated natural water, but had a limited alleviating effect on the irreversible resistance of the membrane. The interfacial free energy analysis showed that the interaction force between the membrane and the simulated natural water was also repulsive after the pre-oxidation, indicating that ClO2 pre-oxidation was an effective way to alleviate cake layer fouling by reducing the interaction between the foulant and the membrane. In addition, ClO2 oxidation activated the hidden functional groups in the raw water, resulting in an increase in the fluorescence value of humic analogs, but had a good removal effect on the fluorescence intensity of BSA. Furthermore, the membrane fouling fitting model showed that ClO2, at a low dose (1 mg/L), could change the mechanism of membrane fouling induced by simulated natural water from standard blocking and cake layer blocking to critical blocking. Overall, ClO2 pre-oxidation was an efficient pretreatment strategy for UF membrane fouling alleviation, especially for the fouling control of HA and SA at low dosages.

scholarly journals Diethylene Glycol-Assisted Organized TiO2 Nanostructures for Photocatalytic Wastewater Treatment Ceramic Membranes

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 750 ◽  
Author(s):  
Ahmad ◽  
Kim ◽  
Kim ◽  
Kim
Keyword(s):  
Wastewater Treatment ◽  
Diethylene Glycol ◽  
Membrane Fouling ◽  
Ceramic Membrane ◽  
Membrane Surface ◽  
Ceramic Membranes ◽  
Tio2 Nanorods ◽  
Hydrolysis Rate ◽  
Capping Agent ◽  
Alumina Support

A high-performance photocatalytic ceramic membrane was developed by direct growth of a TiO2 structure on a macroporous alumina support using a hydrothermal method. The morphological nanostructure of TiO2 on the support was successfully controlled via the interaction between the TiO2 precursor and a capping agent, diethylene glycol (DEG). The growth of anatase TiO2 nanorods was observed both on the membrane surface and pore walls. The well-organized nanorods TiO2 reduced the perturbation of the alumina support, thus controlling the hydrolysis rate of the TiO2 precursor and reducing membrane fouling. However, a decrease in the amount of the DEG capping agent significantly reduced membrane permeability, owing to the formation of nonporous clusters of TiO2 on the support. Distribution of the organized TiO2 nanorods on the support was very effective for the improvement of the organic removal efficiency and antifouling under ultraviolet illumination. The TiO2 nanostructure associated with the reactive crystalline phase, rather than the amount of layered TiO2 formed on the support, which was found to be the key to controlling photocatalytic membrane reactivity. These experimental findings would provide a new approach for the development of efficacious photocatalytic membranes with improved performance for wastewater treatment.

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