scholarly journals The impact of anionic polyacrylamide (APAM) on ultrafiltration efficiency in flocculation-ultrafiltration process

2017 ◽  
Vol 75 (8) ◽  
pp. 1982-1989 ◽  
Author(s):  
Ruijun Zhang ◽  
Shengnan Yuan ◽  
Wenxin Shi ◽  
Cong Ma ◽  
Zhiqiang Zhang ◽  
...  
Keyword(s):  
Membrane Fouling ◽  
Aluminium Chloride ◽  
Optimal Dosage ◽  
Cleaning Efficiency ◽  
Chemical Cleaning ◽  
Membrane Cleaning ◽  
Effluent Quality ◽  
Adsorption Sites ◽  
The Impact ◽  
Anionic Polyacrylamide

With the purpose of improving the ultrafiltration (UF) efficiency, anionic polyacrylamide (APAM) has been used as a coagulant aid in the flocculation-UF process. In this study, the impact of APAM on UF efficiency has been investigated with regard to membrane fouling, membrane cleaning and effluent quality. The results indicated that the optimal dosage of APAM had positive impacts on membrane fouling control, membrane cleaning and effluent quality. According to the flux decline curve, scanning electron microscopy and contact angle characterization, the optimal dosage of APAM was determined to be 0.1 mg/L coupled with 2 mg/L (as Al3+) poly-aluminium chloride. Under this optimal condition, membrane fouling can be mitigated because of the formation of a porous and hydrophilic fouling layer. APAM in the fouling layer can improve the chemical cleaning efficiency of 0.5% NaOH due to the disintegration of the fouling layer when APAM is dissolved under strong alkaline conditions. Furthermore, with the addition of APAM in the flocculation-UF process, more active adsorption sites can be formed in the flocs as well as the membrane fouling layer, thus more antipyrine molecules in the raw water can be adsorbed and removed in the flocculation-UF process.

Study on Fouling of Nanofiltration Membranes when Treating the MBR Effluent

2012 ◽  
Vol 442 ◽  
pp. 157-161
Author(s):  
Xiu Tao Zhang ◽  
Kai Sun
Keyword(s):  
Membrane Fouling ◽  
Sodium Tripolyphosphate ◽  
Membrane Surface ◽  
Sodium Dodecyl ◽  
Sodium Dodecyl Benzene Sulfonate ◽  
Cleaning Efficiency ◽  
Membrane Cleaning ◽  
Eds Analysis ◽  
Inorganic Substances ◽  
Dodecyl Benzene Sulfonate

The source of water in this paper is the effluent of MBR. The pressure of nanofiltration system was monitored during the conditioning phase to check the fouling of nanofiltration membrane. The morphology and distribution of polluants on the membrane surface were examined by scanning electron microscopy (SEM), with additionalenergy dispersive spectrometer (EDS) analysis. Then analyzes the main causes of membrane fouling. And the result of SEM and EDS about membrane showed that, the major foulants of membrane include organic substances and silicon dioxide. And there may be some inorganic substances, which contained magnesium (Mg) and calcium (Ca). Thought cleaning experiments with HCl, STPP (Sodium tripolyphosphate, Na5P3O10) + Na-DDBS (sodium dodecyl benzene sulfonate, C6H5(CH2)12-SO3Na) about fouled membrane, cleaning efficiency is up to 87%.

scholarly journals Maximizing the Impact of Air Bubbles for Membrane Fouling Control in Microalgae Harvesting

2017 ◽  
Vol 78 (1) ◽  
Author(s):  
Arthur Eliseus ◽  
Muhammad Roil Bilad
Keyword(s):  
Membrane Fouling ◽  
Membrane Surface ◽  
Air Bubbles ◽  
Membrane Cleaning ◽  
Shear Rates ◽  
Fouling Control ◽  
Microalgae Harvesting ◽  
Switching Mode ◽  
The Impact ◽  
Better Than

Harvesting microalgae using membrane is challenging due to the nature of microalgae having very high membrane fouling potential. Numerous techniques have been proposed for membrane fouling control, including optimizing operational cycles, imposing shear-rates via air bubbles and dosing chemicals for feed conditioning and membrane cleaning. As an established  method, the eficacy of air bubbles for membrane fouling control can be improved by maximizing the impact of shear-rates in  scouring foulant from the membrane surface. In this study, we investigate the effect of tilting angles, switching periods as well as aeration rates in a lab-scale submerged iltration system by iltering microalgae solution. Results showed that higher tilting angles improve the cleaning eficiency by offering higher lux of up to 2.7 times at an angle of 20◦ as opposed to the vertical one. It was also found that operating a one-sided panel (without switching) was about 20% better than a two-sided panel, in which the latter involved switching mode to offer aeration of both panel sides. This technique is effective in controlling fouling and can lead to energy saving for full-scale modules.

Effects of flocculent aggregates on microfiltration with coagulation pretreatment of high turbidity waters

2006 ◽  
Vol 53 (7) ◽  
pp. 191-197 ◽  
Author(s):  
S. Lee ◽  
J. H. Kweon ◽  
Y. H. Choi ◽  
K.-H. Ahn
Keyword(s):  
Drinking Water ◽  
Membrane Fouling ◽  
Raw Water ◽  
Cleaning Efficiency ◽  
Membrane Cleaning ◽  
Han River ◽  
Turbid Waters ◽  
Flux Decline ◽  
Negative Effect ◽  
High Turbidity

Immersed membrane systems, and those with in-line coagulation, have been extensively applied in drinking water systems. Sedimentation is usually replaced by membrane processes in both systems. In these systems, voluminous flocculent aggregates formed during coagulation could be potential foulants. When raw waters with high turbidity are introduced, particle loadings to membrane due to coagulation pretreatment are enormous and thus could increase fouling. In general, during the rainy season, the turbidity of the Han River water, which supplies drinking water for the City of Seoul, Korea, is more than a hundred times higher than usual. Therefore, effects of floc on membrane fouling were investigated with highly turbid waters. Two turbidity concentrations, 40 and 200 NTU, were formulated by the addition of kaolin (used as a natural particle surrogate) to the Han River raw water. The results showed that the flux decline behaviours of the highly turbid waters were different from those of natural raw water. Coagulation pretreatment was very effective at reducing membrane fouling. Flocculent aggregates showed a negative effect on the flux decline, but a positive effect on the membrane cleaning efficiency.

A study on membrane fouling due to algal deposition

2000 ◽  
Vol 41 (10-11) ◽  
pp. 327-335 ◽  
Author(s):  
S. Babel ◽  
S. Takizawa
Keyword(s):  
Organic Matter ◽  
Membrane Fouling ◽  
Cell Lysis ◽  
Chemical Cleaning ◽  
Membrane Cleaning ◽  
Treatment Techniques ◽  
Ozone Pretreatment ◽  
Extensive Cell ◽  
Pre Treatment ◽  
Physical And Chemical

Batch filtration experiments in dead-end mode were carried out to investigate the membrane fouling phenomenon due to Chlorella deposition and to analyse the effectiveness of pretreatment techniques to control membrane fouling. Experiments were also conducted to identify efficient and effective physical and chemical methods for cleaning the membrane. For both cellulose acetate and PVDF membranes, the effect of algal concentration was found similar. Initially when the deposition was less, the flux was high and the resistance was very low or negligible. As the deposition increased, the resistance increased exponentially. With further increase in deposition, the resistance increases linearly at a constant rate. Among the three pre-treatment techniques studied, coagulation with alum and ozonation were effective in controlling the fouling of membrane. Chlorine pretreatment was not effective in reducing the algal cake resistance because it brought about an extensive cell lysis. Photographs taken by Scanning Electron Microscope (SEM) showed damage to the cell surface architecture and release of organic matter to the medium after chlorination. Ozone pretreatment was more effective than chlorine in disintegrating only the extracelluar organic matter (EOM) without causing cell lysis, thus bringing down the algal cake resistance. Cleaning experiments after algal filtration without pre-treatment showed that physical cleaning was less effective than chemical cleaning. All four chemicals tested for membrane cleaning could reduce the cake resistance by more than 99%.

scholarly journals Membrane cleaning in membrane distillation of reverse osmosis concentrate generated in landfill leachate treatment

2021 ◽  
Author(s):  
Xiaolin Jia ◽  
Kuiling Li ◽  
Baoqiang Wang ◽  
ZhiChao Zhao ◽  
Deyin Hou ◽  
...  
Keyword(s):  
Reverse Osmosis ◽  
Landfill Leachate ◽  
Membrane Fouling ◽  
Membrane Distillation ◽  
Water Recovery ◽  
Permeate Flux ◽  
Chemical Cleaning ◽  
Leachate Treatment ◽  
Membrane Cleaning ◽  
Cleaning Methods

Abstract As a thermally induced membrane separation process, membrane distillation (MD) has drawn more and more attention for the advantages of treating hypersaline wastewaters, especially the concentrate from reverse osmosis (RO) process. One of the major obstacles in widespread MD application is the membrane fouling. We investigated the feasibility of direct contact membrane distillation (DCMD) for landfill leachate reverse osmosis concentrate (LFLRO) brine treatment and systematically assessed the efficiency of chemical cleaning for DCMD after processing LFLRO brine. The results showed that 80% water recovery rate was achieved when processing the LFLRO brine by DCMD, but the membrane fouling occurred during the DCMD process, and manifested as the decreasing of permeate flux and the increasing of permeate conductivity. Analysis revealed that the serious flux reduction was primarily caused by the fouling layer that consist of organic matters and inorganic salts. Five cleaning methods were investigated for membrane cleaning, including hydrogen chloride (HCl)-sodium hydroxide (NaOH), ethylene diamine tetraacetic acid (EDTA)-NaOH, critic acid, sodium hypochlorite (NaClO) and sodium dodecyl sulphate (SDS) cleaning. Among the chemical cleaning methods investigated, the 3 wt.% SDS cleaning showed the best efficiency at recovering the performance of fouled membranes.

scholarly journals Cleaning optimisation of reverse osmosis membranes used for wastewater reclamation

2012 ◽  
Vol 2 (1) ◽  
pp. 47-54
Author(s):  
X. Bernat ◽  
G. Prats ◽  
O. Gibert ◽  
B. Lefèvre ◽  
J. Tobella
Keyword(s):  
Reverse Osmosis ◽  
Municipal Wastewater ◽  
Economic Feasibility ◽  
Low Molecular Weight ◽  
Wastewater Reclamation ◽  
Tertiary Treatment ◽  
Cleaning Efficiency ◽  
Membrane Cleaning ◽  
The Impact ◽  
Cleaning Protocol

Wastewater reclamation contributes to the preservation of conventional water resources and thus helps to ensure appropriate human development for future generations. Wastewater reclamation can be achieved through several technologies. One of the most common technologies is the tertiary treatment of urban municipal wastewater, which is often based on membrane technologies. Reverse osmosis is an effective separation technology for removing dissolved salts and low molecular weight organic compounds. However, membranes suffer from fouling, which directly reduces technical, environmental and economic feasibility of the process and hence of the reclamation plant. One of the strategies helpful to reduce fouling is the optimisation of the membranes’ cleaning and maintenance. The aim of this work is to test the impact of the membrane cleaning protocol design on the recovery of the original properties of a reverse osmosis membrane used for several years in a wastewater reclamation plant in Spain. Furthermore, the work is focused on the validation of the adequacy of the most-common indicators used for assessing membranes’ cleaning efficiency.

scholarly journals An analysis of the effects of pressure-assisted osmotic backwashing on the high recovery reverse osmosis system

2019 ◽  
Vol 69 (3) ◽  
pp. 298-318 ◽  
Author(s):  
Naveenkumar Ashok Yaranal ◽  
Sneha Kumari ◽  
Selvaraju Narayanasamy ◽  
Senthilmurugan Subbiah
Keyword(s):  
Reverse Osmosis ◽  
Membrane Fouling ◽  
Low Cost ◽  
Water Pressure ◽  
Operating Parameter ◽  
High Recovery ◽  
Cleaning Efficiency ◽  
Membrane Cleaning ◽  
Number Of Leaves ◽  
Ro Membrane

Abstract The low cost simplified method for implementation of pressure-assisted osmotic (PAO) backwash (BW) for spiral wound reverse osmosis (RO) membrane module is presented in this work. The effect of membrane design and an operating parameter concerning the efficiency of PAO membrane BW is analyzed. The following design and operating parameters are considered in this study: (i) spacer thickness, (ii) dimension of the permeate channel, (iii) number of leaves, and (iv) BW water pressure. The performance of PAO BW with respect to membrane cleaning efficiency is analyzed for three different high recovery RO systems by purifying 1,500 liters of water. The membrane cleaning efficiency is measured by examining the rate of permeate quality and quantity decline using ASTM D4516 method. Finally, to quantify the membrane fouling with respect to different high recovery configurations, the thickness, and composition of foulants present in the used membrane's surface are measured by using field emission scanning electron microscope with energy dispersive X-ray (FESEM-EDX). The result concludes that the RO membrane operated at high recovery with PAO BW is found to have less fouling deposits than membrane without PAO BW.

Analysis of organic matter causing membrane fouling in drinking water treatment

2000 ◽  
Vol 41 (10-11) ◽  
pp. 59-67 ◽  
Author(s):  
Y. Kaiya ◽  
Y. Itoh ◽  
S. Takizawa ◽  
K. Fujita ◽  
T. Tagawa
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Membrane Fouling ◽  
Drinking Water Treatment ◽  
Gas Chromatography Mass Spectrometry ◽  
Raw Water ◽  
Cleaning Efficiency ◽  
Chemical Cleaning

A study was conducted on characteristics of membrane-fouling matter and chemical cleaning of fouled membranes. The membranes were those used for the filtration of raw water taken from the Lake Kitaura, Ibaraki, Japan. Analysis of the molecular weight distribution of extracted foulants by ultrafilters showed that 23% of organic matter was in the fraction exceeding a molecular weight of 100,000 daltons and 33% between 10,000 to 100,000 daltons. Analysis by gel permeation chromatography (GPC) revealed a void peak and five peaks at a molecular weight of less than 6,000 daltons. Assessment by Fourier transform infrared spectroscopy( FTIR) and pyrolysis gas chromatography mass spectrometry (Py-GC-MS) revealed that organic fouling matter contained polysaccharides, proteins, amino sugars and aromatic compounds that constitute humic substances. A comparison of the apparent molecular weight distribution and the FTIR spectra of both the raw water and fouled membrane extracts revealed the attachment of membrane-fouling matter nonexistent in the raw water, which was considered to be extracellular organic matter. Chemical cleaning of fouled membranes suggested that sodium hypochlorite and hydrogen peroxide were effective for the recovery of membrane permeability. In most of the experiments, the higher the cleaning temperature is between 5°C and 40°C, the more effective the chemical cleaning. However, chemical cleaning by a mixture of 1%-NaOCl and 4%-NaOH showed a comparable cleaning efficiency at 5°C as chemical cleaning at 40°C after two hours.

scholarly journals Membrane fouling control and cleaning technology of ceramic membrane treating wastewater

2019 ◽  
Vol 118 ◽  
pp. 04023
Author(s):  
Guoqiang Ma ◽  
Shoubin Zhang ◽  
Yanming Yang ◽  
Liping Qiu ◽  
Guicai Liu ◽  
...  
Keyword(s):  
Membrane Fouling ◽  
Ceramic Membrane ◽  
Effective Means ◽  
Stable Operation ◽  
Efficient Technology ◽  
Chemical Cleaning ◽  
Membrane Cleaning ◽  
Membrane Technique ◽  
Cleaning Methods ◽  
Cleaning Technology

Ceramic membrane technique was a new and efficient technology for wastewater treatment and used more and more widely in recent years. Controlling membrane fouling was the key method to ensure the efficient and stable operation of ceramic membrane. In this paper, the causes, influencing factors and control methods of ceramic membrane fouling were summarized. As one of the most effective means to control membrane fouling, several common membrane cleaning methods, such as physical cleaning, chemical cleaning, ultrasonic cleaning and combined cleaning, were introduced. And the application of ceramic membrane cleaning was presented too. Then the future directions for ceramic membrane techniquresearching was prospected.

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