Effect of Aggregated Floc Circulation on Membrane Fouling in Contact Circulated Coagulation-Membrane Filtration Hybrid Process for Treatment of Surface Water

2013 ◽  
Vol 864-867 ◽  
pp. 1226-1232
Author(s):  
Xue Hui Zhao ◽  
Hong Wei Zhang ◽  
Jie Wang

The effect of aggregated floc circulation on membrane fouling in contact circulated coagulation-membrane filtration hybrid process for treatment of surface water was investigated in this study. In order to understand the floc characteristics, the floc formation, breakage and re-growth were monitored by Mastersizer 2000 under the coagulation dosage of 5, 10, 15 and 20mg/l. A contact circulated coagulation tests were carried out and the effluent was filtered by a dead-end micro-filtration with the hollow fibre membrane. The coagulation effluent quality and the relative permeability J/J0 of membrane was determined at the circulated floc dosage of 22, 44 and 66mg/l. The experiment results indicated that the addition of circulated floc obviously improved the flux decline and the degree of improvement was closely related to the dosage of circulated floc. Compared to traditional coagulation, the contact circulated coagulation was an economic and efficient method to retard the membrane fouling.


Membranes ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 460
Author(s):  
Bastiaan Blankert ◽  
Bart Van der Bruggen ◽  
Amy E. Childress ◽  
Noreddine Ghaffour ◽  
Johannes S. Vrouwenvelder

The manner in which membrane-fouling experiments are conducted and how fouling performance data are represented have a strong impact on both how the data are interpreted and on the conclusions that may be drawn. We provide a couple of examples to prove that it is possible to obtain misleading conclusions from commonly used representations of fouling data. Although the illustrative example revolves around dead-end ultrafiltration, the underlying principles are applicable to a wider range of membrane processes. When choosing the experimental conditions and how to represent fouling data, there are three main factors that should be considered: (I) the foulant mass is principally related to the filtered volume; (II) the filtration flux can exacerbate fouling effects (e.g., concentration polarization and cake compression); and (III) the practice of normalization, as in dividing by an initial value, disregards the difference in driving force and divides the fouling effect by different numbers. Thus, a bias may occur that favors the experimental condition with the lower filtration flux and the less-permeable membrane. It is recommended to: (I) avoid relative fouling performance indicators, such as relative flux decline (J/J0); (II) use resistance vs. specific volume; and (III) use flux-controlled experiments for fouling performance evaluation.



2001 ◽  
Vol 43 (10) ◽  
pp. 225-232 ◽  
Author(s):  
C. Jarusutthirak ◽  
G. Amy

The reuse of treated wastewater to augment natural drinking water supplies is receiving serious consideration. Treatment of secondary and tertiary effluent by membrane filtration was investigated by assessing nanofiltration (NF) membrane and ultrafiltration (UF) membranes in bench-scale experiments. It was found that secondary and tertiary effluent contained high concentration of effluent organic matter (EfOM), contributing EfOM-related fouling. Flux decline and EfOM rejection tests were evaluated, using a dead-end stirred cell filtration unit. Surface charge and molecular weight cut-off (MWCO) of membranes were significant factors in membrane performance including permeability and EfOM-rejection.



2018 ◽  
Vol 19 (3) ◽  
pp. 855-863 ◽  
Author(s):  
T. Miyoshi ◽  
Y. Takahashi ◽  
T. Suzuki ◽  
R. Nitisoravut ◽  
C. Polprasert

Abstract This study investigated the performance of a hybrid membrane filtration system to produce industrial water from highly-colored surface water. The system consists of a membrane filtration process with appropriate pretreatments, including coagulation, pre-chlorination, and anion exchange (IE) process. The results of the pilot-scale experiments revealed that the hybrid system can produce treated water with color of around 5 Pt-Co, dissolved manganese concentration of no more than 0.05 mg/L, and a silt density index (SDI) of no more than 5 when sufficient coagulant and sodium hypochlorite were dosed. Although the IE process effectively reduced the color of the water, a moderate increase in the color of the IE effluent was observed when there was a significant increase in the color of the raw water. This resulted in a severe membrane fouling, which was likely to be attributed to the excess production of inorganic sludge associated with the increased coagulant dosage required to achieve sufficient reduction of color. Such severe membrane fouling can be controlled by optimising the backwashing and relaxation frequencies during the membrane filtration. These results indicate that the hybrid system proposed is a suitable technology for treating highly-colored surface water.



Membranes ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 149 ◽  
Author(s):  
Bin Huang ◽  
Hangkun Gu ◽  
Kang Xiao ◽  
Fangshu Qu ◽  
Huarong Yu ◽  
...  

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.



Membranes ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 213
Author(s):  
Stéphane Venne ◽  
Onita D. Basu ◽  
Benoit Barbeau

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.





2017 ◽  
Vol 76 (2) ◽  
pp. 490-500 ◽  
Author(s):  
Yufei Wang ◽  
Hui Jia ◽  
Hongwei Zhang ◽  
Jie Wang ◽  
Wenjin Liu

A recycling magnetic flocculation membrane filtration (RMFMF) process integrating circulating coagulation, magnetic enhanced flocculation and membrane filtration was investigated for the treatment of surface water micro-polluted by tetracycline, a typical pharmaceutical and personal care product. A bench-scale experiment was conducted and several water quality parameters including turbidity, ultraviolet absorbance at 254 nm (UV254), total organic carbon and tetracycline concentration were evaluated, taking coagulation membrane filtration and magnetic flocculation membrane filtration processes as reference treatments. The experimental results showed that at the optimum doses of 20 mg·L−1 ferric chloride (FeCl3), 4 mg·L−1 magnetite (Fe3O4) and 6 mg·L−1 reclaimed magnetic flocs in RMFMF processes, removal efficiencies of above evaluated parameters ranged from 55.8% to 92.9%, which performed best. Simultaneously, the largest average particle size of 484.71 μm and the highest fractal dimension of 1.37 of flocs were achieved, which did not only present the best coagulation effect helpful in enhancing the performance of removing multiple contaminants, but also lead to the generation of loose and porous cake layers favouring reduced permeate flux decline and membrane fouling.



2011 ◽  
Vol 64 (8) ◽  
pp. 1685-1691 ◽  
Author(s):  
T. Li ◽  
B. Z. Dong ◽  
Z. Liu ◽  
W. H. Chu

Algogenic organic matter (AOM) was extracted from blue-green algae (cyanobacteria) and its characteristic was determined by various methods including high-pressure size-exclusion chromatography (HP-SEC), hydrophobic and hydrophilic fractionation, molecular weight (MW) fractionation and fluorescence excitation emission matrix (EEM). The results revealed that AOM was hydrophilic fractionation predominantly, accounting for 78%. The specific ultraviolet absorbance of AOM was 1.1 L/(mg m) only. The analysis for MW distribution demonstrated that organic matter greater than 30,000 MW accounted for over 40% and was composed of mostly neutral hydrophilic compound. EEM analyses revealed that protein-like and humic-substances existed in AOM. A test for membrane filtration exhibited that AOM could make ultrafiltration membrane substantial flux decline, which can be attributed to membrane pore clog caused by neutral hydrophilic compound with larger MW.



RSC Advances ◽  
2016 ◽  
Vol 6 (1) ◽  
pp. 163-173 ◽  
Author(s):  
Jun Nan ◽  
Meng Yao ◽  
Qinggui Li ◽  
Dan Zhan ◽  
Ting Chen ◽  
...  

The impact of shear conditions during coagulation on the ultrafiltration permeate flux in a coagulation–ultrafiltration (C–UF) process was investigated.



2017 ◽  
Vol 3 (2) ◽  
Author(s):  
Raissa Rosadi ◽  
Mahmud Mahmud ◽  
Chairul Abdi

ABSTRAK Penyisihan kandungan bahan organik alami (BOA) pada air gambut dengan menggunakan membran ultrafiltrasi polisulfon mempunyai kendala berupa terjadinya fouling membran. Proses hibrid koagulasi satu tahap dan ultrafiltrasi diketahui hanya mampu menyisihkan kandungan BOA yang bersifat hidrofobik dan sebagian kandungan hidrofilik. Penggunaan koagulasi dua tahap diduga mampu mengurangi potensi fouling pada membran, serta lebih baik dalam menyisihkan kandungan BOA hidrofobik dan hidrofilik. Penelitian ini bertujuan untuk mendapatkan dosis dan tekanan optimum pada proses hibrid koagulasi dua tahap dan UF-PSf dalam menyisihkan kandungan BOA air gambut, serta mengetahui pengaruh praperlakuan koagulasi dua tahap terhadap perubahan nilai fluks pada membran UF-PSf. Proses koagulasi menggunakan alat jar test dengan koagulan Al2(SO4)3. Sistem filtrasi pada membran UF-PSf menggunakan sistem aliran dead-end. Kondisi operasi optimum pada proses hibrid koagulasi dua tahap dan UF-PSf didapatkan pada dosis 175 mg/L dan tekanan filtrasi 3 bar dengan besar penyisihan BOA zat organik KMnO4 dan UV254 berturut-turut sebesar 97,32% dan 96,02%%. Praperlakuan koagulasi dua tahap memberikan pengaruh terhadap nilai fluks yang semakin besar pada proses hibrid koagulasi dua tahap dan UF-PSf. Nilai fluks pada tekanan optimum 3 bar yaitu sebesar 154,84 L/m2.jam. Kata kunci:   Air gambut, bahan organik alami,  fouling membran, koagulasi dua tahap, membran ultrafiltrasi polisulfon. ABSTRACT  Removal of natural organic matter (NOM) on peat water by Polysulfone ultrafiltration membrane (UF-PSf) have some of promblem, namely membrane fouling. Hybrid process of one-stage coagulation and UF-PSf can remove hydrophobic and some hydrophilic content of NOM. Two stage coagulation was allegedly able to decrease membrane fouling, and better to remove hydrophobic and hydrophilic content of NOM. The purpose of this reseach is to find the optimum dose and pressure on two stage coagulation and UF-PSf hybrid process to remove NOM in peat water, and to known the effect of two stage coagulation pretreatment towards flux value changes on UF-PSf membranes. The coagulation process using jar test instrument with Al2(SO4)3 coagulant. The filtration system on the UF-PSf membrane using dead-end flow system. The optimum dose and pressure on hybrid process of two stage coagulation and UF-PSf is 175 mg/L and 3 bar with BOA removal of organic subtances KMnO4 and UV254 respectively amounted to 97,32% and 96,02%. Two stage coagulation pretreatment giving icreasing the flux value on two stage coagulation and UF-PSf hybrid process. The flux value of optimum pressure at 3 bar is 154,84L/m2.hours.  Keywords:    peat water, natural organic matter (NOM), fouling membrane, two stage coagulation,           polysulfone ultrafiltration membrane.



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