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.

Predictability of fouling-potential of raw water for ultrafiltration membranes

2011 ◽  
Vol 11 (4) ◽  
pp. 481-489
Author(s):  
S. Krause ◽  
A. Obermayer
Keyword(s):  
Water Quality ◽  
Membrane Fouling ◽  
Large Scale ◽  
High Capacity ◽  
Raw Water ◽  
Ultrafiltration Membranes ◽  
Small Water ◽  
Lab Experiments ◽  
Flux Decline ◽  
Public Drinking Water

The public drinking water supply of southern Germany is characterized by a rather decentralized network. Due to the hydrogeological setting in these parts of Germany many of the small water works with an average capacity of 50 m3/h have to treat raw water extracted from karstic or cliffy aquifers. These raw waters tend to be contaminated with particles and pathogens acquired during snowmelt or after strong rainfalls. In the last decade ultrafiltration has become the technology of choice for the removal of the aforementioned contaminants. Flux decline caused by unanticipated membrane fouling is the main limitation for the application of ultrafiltration membranes. This paper describes how membrane fouling phenomena can be predicted by using a statistical approach based on data from large scale filtration systems in combination with field and lab experiments on raw water quality and membrane performance. The data defines water quality and respective fouling phenomena both in technical scale filtration plants and in lab experiments of eleven different raw waters. The method described here is more economically feasible for small water works when compared to typical pilot experiments that are used for high capacity water works.

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.

Influence of calcium-NOM complexes on fouling of nanofiltration membranes in drinking water production

2006 ◽  
Vol 6 (4) ◽  
pp. 171-178 ◽  
Author(s):  
E.R. Cornelissen ◽  
W.G. Siegers ◽  
J. Ogier ◽  
E.F. Beerendonk
Keyword(s):  
Drinking Water ◽  
Membrane Fouling ◽  
Calcium Concentration ◽  
Calcium Content ◽  
Free Calcium ◽  
Feed Water ◽  
Nanofiltration Membranes ◽  
Water And Wastewater Treatment ◽  
Particulate Fouling ◽  
Flux Decline

The application of nanofiltration is growing rapidly in drinking water and wastewater treatment. The main problem during the operation of nanofiltration membranes is membrane fouling, part of which is due to the presence of Natural Organic Matter (NOM) in sources for drinking water. In this work the effect of calcium was investigated on the nanofiltration fouling behavior in relation to NOM. From Li and Elimelech (2004) it is known that calcium enhanced membrane fouling significantly due to the formation of calcium-NOM complexes. Two techniques were used in our research to determine the part of calcium which is complexated by NOM and the free calcium ion in solution. Results showed that a minimum calcium concentration and a minimum NOM concentration were required for calcium-NOM complex formation. Furthermore, the influence of the calcium concentration on the flux decline during nanofiltration experiments was investigated for different types of feed water. The observed flux decline was proven to be only caused by NOM fouling rather than other membrane fouling types, such as biofouling, scaling or particulate fouling. Fouling of nanofiltration membranes was related to the calcium content in the feed water, and more specifically to the calcium-NOM complex concentration. Membrane cleaning with SDS was found to be very effective.

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%.

RO filtration of biologically treated textile and dyeing effluents using ozonation as a pre-treatment

2010 ◽  
Vol 62 (4) ◽  
pp. 751-758 ◽  
Author(s):  
H. Y. Wang ◽  
Y. T. Guan ◽  
T. Mizuno ◽  
H. Tsuno
Keyword(s):  
Organic Matter ◽  
Membrane Fouling ◽  
Quality Parameters ◽  
Dyeing Wastewater ◽  
Improve Performance ◽  
Membrane Cleaning ◽  
Membrane Flux ◽  
Flux Decline ◽  
Pre Treatment ◽  
Water Purity

Bench-scale experiments were conducted to investigate the application of ozonation pre-treatment for biologically treated textile and dyeing wastewater to improve performance of the RO process. Based on ozonation experiments, four specific ozone consumptions (SOC), 0, 0.3, 0.6, 4.0 mg O3/mg DOC0 were chosen for study of the effects of ozonation on the reverse osmosis (RO) process. Membrane flux was recorded. Also, the permeate water quality parameters such as TOC, conductivity were analyzed. In addition, fouled membrane cleaning was studied. The study further examined the nature and mechanisms of membrane fouling using scanning electron microscopy (SEM) and the energy dispersive X-ray spectrometer (EDS). The effect of ozonation on RO filtration was found to depend on SOC. The study revealed that significant improvement can be achieved in the efficiency of RO filtration by employing ozonation with 0.6 mg O3/mg DOC0 SOC. Although the product water purity slightly decreased, the ozonation pre-treatment showed advantages at 0.6 mg O3/mg DOC0 SOC for the following: (i) mitigation of flux decline due to membrane fouling; (ii) improvement in foulants cleanability. In addition, hypotheses were put forward to explain the reasons from the aspect of organic matter characteristics changed by ozonation, such as changing on functional groups and molecular weight of organic matter.

Effect of coagulation mechanisms on the fouling and ultrasonic cleaning of PTFE membrane

2012 ◽  
Vol 66 (11) ◽  
pp. 2291-2298 ◽  
Author(s):  
Meng-Wei Wan ◽  
Cybelle Morales Futalan ◽  
Cheng-Hung Chang ◽  
Chi-Chuah Kan
Keyword(s):  
Membrane Fouling ◽  
Permeate Flux ◽  
Cleaning Efficiency ◽  
Ultrasonic Cleaning ◽  
Ptfe Membrane ◽  
Pore Blocking ◽  
Dead End ◽  
Flux Decline ◽  
Cake Formation ◽  
Scanning Electron

In this study, the effect of coagulation pretreatment on membrane fouling and ultrasonic cleaning efficiency was investigated using a dead-end polytetrafluoroethylene (PTFE) microfiltration system. The extent of membrane fouling was examined under different coagulation mechanisms such as charge neutralization (CN), electrostatic patch effect (EPE) and sweep flocculation (SW). Fouling through EPE mechanism provided the greatest flux decline and least permeate flux recovery over CN and SW. EPE produces more stable, smaller and more compact flocs while CN and SW have large, easily degraded and highly-branched structured flocs. The predominant fouling mechanism of EPE, CN and SW is pore blocking, a combination of pore blocking and cake formation, and cake formation, respectively. Better permeate flux recovery is observed with SW over CN and EPE, which implies formation of less dense and more porous cake deposits. The morphology of fouled membranes was examined using scanning electron microscopy (SEM).

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.

Advanced treatment for taste and odour control in drinking water: case study of a pilot scale plant in Seoul, Korea

2007 ◽  
Vol 55 (5) ◽  
pp. 111-116 ◽  
Author(s):  
W.H. Joe ◽  
I.C. Choi ◽  
Y.A. Baek ◽  
Y.J. Choi ◽  
G.S. Park ◽  
...  
Keyword(s):  
Drinking Water ◽  
Removal Efficiency ◽  
Tap Water ◽  
Pilot Scale ◽  
Chlorine Concentration ◽  
Advanced Treatment ◽  
Raw Water ◽  
Han River ◽  
Odour Control

Taste and odour problems of tap water in Seoul are attributed to 2-methylisoborneol (2-MIB) and trans-1,10-dimethyl-trans-9-decalol (geosmin), which are the result of metabolism of algae and chlorine for disinfection. This study was carried out to measure 2-MIB and geosmin in the raw water from the Han River, to investigate removal efficiency of GAC and BAC integrated with post-ozonation, and to minimise and quantify the required chlorine concentration as a final disinfectant through the candidate process.

Fouling of low-pressure membranes during drinking water treatment: effect of NOM components and biofiltration pretreatment

2013 ◽  
Vol 14 (3) ◽  
pp. 453-460 ◽  
Author(s):  
I. Rahman ◽  
S. Ndiongue ◽  
X. Jin ◽  
M. I. Van Dyke ◽  
W. B. Anderson ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Membrane Fouling ◽  
Drinking Water Treatment ◽  
Low Pressure ◽  
Pilot Scale ◽  
Substantial Improvement ◽  
Raw Water ◽  
Minimal Impact ◽  
Detection Analysis

Fouling is a major challenge for low-pressure membrane drinking water treatment systems. Previous research has demonstrated that under the right conditions, biofiltration is an effective method to reduce fouling of low-pressure polymeric membranes. This study provides additional insight into the effect of biofiltration as a pretreatment for fouling reduction by using river water with different raw water quality characteristics than has been examined in previous studies. Two parallel pilot-scale dual media (sand/anthracite) biological filters were operated continuously over a period of 14 months. Liquid chromatography–organic carbon detection analysis confirmed that the parallel biofilters performed similarly with both averaging on 21% biopolymer removal. Raw and treated water biopolymer concentrations were correlated, with increased absolute removals occurring at higher raw water concentrations. Ultrafiltration (UF) membrane fouling experiments showed substantial improvement in performance following biofiltration pretreatment by reducing hydraulically irreversible and reversible fouling rates by 14–68% and 8–55%, respectively. The results also reaffirm the importance of biopolymers at concentrations as low as ∼0.1 mg/L on irreversible and reversible UF membrane fouling and a minimal impact of humic substances.

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