scholarly journals A new backwash strategy for reducing the cost of an immersed ultrafiltration system by restricting cake layer breakage

2020 ◽  
Vol 20 (4) ◽  
pp. 1453-1462
Author(s):  
Fangshu Qu ◽  
Xiaolian Li ◽  
Junguo He ◽  
Zhihui Pan ◽  
Yan Zhao ◽  
...  
Keyword(s):  
Membrane Fouling ◽  
Particle Deposition ◽  
Membrane Surface ◽  
Water Plant ◽  
Cake Layer ◽  
Driven System ◽  
Gravity Driven ◽  
Running Cost ◽  
The Cost ◽  
Potable Water Treatment

Abstract Ultrafiltration (UF) is increasingly used for potable water treatment, but membrane fouling necessitates the application of periodical backwash, which increases running cost. A new backwash strategy, in which air scouring was only applied with sludge water discharging, was proposed to improve backwash performance in a water plant using UF. Four gravity-driven UF systems were simultaneously run at increasing air scouring intervals (3–24hours) and sludge water discharging intervals (12–24hours). The membrane fluxes were monitored to assess membrane fouling and the mix solution turbidity was also monitored to investigate deposition of particles. The results indicated that membrane fouling was not aggravated by the extension of air scouring and sludge water discharging intervals. Water backwash on its own induced a shift of particle deposition from the membrane surface to the bottom of the membrane tank due to limited cake layer breakage, enabling the extension of sludge water discharging intervals. For the gravity-driven system investigated, the running cost, including energy, water and chemical demand, was reduced by 16.67% as the air scouring and sludge water discharging intervals increased from 3hours to 24hours and from 12hours to 24hours, respectively.

scholarly journals Algae-Laden Fouling Control by Gravity-Driven Membrane Ultrafiltration with Aluminum Sulfate-Chitosan: The Property of Floc and Cake Layer

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1990 ◽  
Author(s):  
Peng Du ◽  
Xing Li ◽  
Yanling Yang ◽  
Zhiwei Zhou ◽  
Xiaoyan Fan ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Water Treatment ◽  
Membrane Fouling ◽  
Aluminum Sulfate ◽  
Membrane Surface ◽  
Treatment Method ◽  
Cake Layer ◽  
Important Approach ◽  
Gravity Driven ◽  
Parallel Tests

Gravity-driven membrane (GDM) ultrafiltration is a promising water treatment method due to its low energy consumption and low maintenance. However, the low stable permeability in algae-laden water treatment is currently limiting its wider application. With the ultimate goal of increasing permeability, the aim of this study was to evaluate the effect of a composite coagulant of aluminum sulfate-chitosan (AS-CS) on the GDM filtration performance. In parallel tests with a single AS coagulant and without pre-coagulation, the analysis of membrane fouling resistance and the membrane fouling mechanism were evaluated. The results indicated that the AS-CS/GDM system can alleviate 23.74% and 58.80% membrane fouling, respectively, compared with AS/GDM and the GDM system. The AS-CS/GDM system can effectively remove humic-like substances having a molecular weight (MW) of 3–100 kDa, resulting in removal of 98.32% of algae cells and removal of 66.25% of dissolved organic carbon; the AS-CS/GDM system thereby improved the concentration of attached biomass on the membrane surface with the stronger biodegradability of organic matters. The application of AS-CS pre-coagulation in the GDM process could enhance the proliferation of microorganisms and the removal of low molecular weight humic-like substances. Therefore, the AS-CS/GDM system is a potentially important approach for algae-laden water treatment.

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 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.

scholarly journals A Study on Membrane Filtration Characteristics of Methanogenic Mixed Liquor in Two Phase Anaerobic Digestion of Food Waste

2020 ◽  
Vol 42 (3) ◽  
pp. 151-163
Author(s):  
Min-Ju Park ◽  
Gyu-Tae Seo
Keyword(s):  
Anaerobic Digestion ◽  
Food Waste ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Membrane Surface ◽  
Solid Retention Time ◽  
Two Phase ◽  
Mixed Liquor ◽  
Cross Flow Filtration ◽  
Cake Layer

Objectives:An experimental study was conducted to investigate the membrane filtration characteristics of mixed liquor in methanogenic reactor to extend solid retention time (SRT) in food waste anaerobic digestion system.Methods:On the basis of the particle size distribution (0.5~700 µm) of the methanogenic mixed liquor, three grade membranes (MF, UF, NF) were tested in a stirred cell filtration and a plate type module. Furthermore foulants of membrane, especially UF, was investigated by SEM-EDS, FTIR, SEC.Results and Discussion:As a result UF membrane was selected for stable filtration of the liquor in terms of flux (2.51 L/m<sup>2</sup>･h･bar) and the flux recovery (100%) as well as filtration resistance (Total 7.15.E+13 m<sup>-1</sup>). Average flux was 18 L/m<sup>2</sup>･h･bar for the selected UF membrane in cross flow filtration using a flat plate module. The filtration results showed that membrane fouling was caused by gel and cake layer formed on the membrane surface and 90% of the initial flux could be recovered by physical washing. It was identified that major fouling causing materials were byproducts of carbohydrate and protein decomposition, and small amount of inorganic substance detected on the membrane surface were salt and struvite like materials.Conclusions:Based on the membrane filtration characteristics analyzed from the study, the UF membrane coupled anaerobic digestion is feasible to be applied as a novel food waste treatment system for SRT extension of the methanogenic reactor.

scholarly journals Performance of an indigenous integrated slurry photocatalytic membrane reactor (PMR) on the removal of aqueous phenanthrene (PHE)

2018 ◽  
Vol 77 (11) ◽  
pp. 2642-2656 ◽  
Author(s):  
C. Nirmala Rani ◽  
S. Karthikeyan
Keyword(s):  
Membrane Fouling ◽  
Membrane Reactor ◽  
Membrane Surface ◽  
Continuous Process ◽  
Permeate Flux ◽  
Toc Removal ◽  
Recovery Potential ◽  
Cake Layer ◽  
Alkaline Conditions ◽  
Photocatalytic Membrane Reactor

Abstract In this study, a slurry photocatalytic membrane reactor (PMR) was developed and evaluated for the degradation of aqueous phenanthrene (PHE). During continuous process with a hydraulic retention time (HRT) of 140 min, the maximum PHE degradation and total organic carbon (TOC) removal efficiencies were found to be 97% and 79%, respectively. The reuse and recovery potential of TiO2 was studied with continuous recycling. The major intermediates during photodegradation of PHE were found to be phenanthrenequinone, phenanthenol and fluorine. This study also includes an investigation of membrane fouling caused by hydrophilic nano TiO2. The cake layer observed on the membrane surface was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and energy dispersive spectroscopy (EDS). In addition, the effect of operating parameters such as pH and permeate flux on membrane fouling were also investigated. Low permeate flux and alkaline conditions reduced membrane fouling.

scholarly journals Effect and mechanism of reduced membrane bioreactor fouling by powdered activated carbon

2021 ◽  
Vol 83 (5) ◽  
pp. 1005-1016
Author(s):  
Yongji Zhang ◽  
Xiaotong Wang ◽  
Hexiu Ye ◽  
Lingling Zhou ◽  
Zhiling Zhao
Keyword(s):  
Activated Carbon ◽  
Membrane Fouling ◽  
Positive Impact ◽  
Membrane Surface ◽  
Polluted Water ◽  
Transmembrane Pressure ◽  
Carbon Membrane ◽  
Cake Layer ◽  
Cleaning Methods ◽  
Alkaline Cleaning

Abstract Powered Activated Carbon – Membrane Bioreactors (PAC-MBRs) have been used with good results for slightly polluted water treatment. Our batch experiments showed that the transmembrane pressure of a PAC-MBR was 25% less than that of a MBR in one period of test, which indicated that PAC did help control the fouling in MBRs. Based on this observation, several mechanisms of membrane fouling of MBRs and PAC-MBRs were investigated to have some insight into how PAC brought a positive impact. The total resistances decreased by 60% and different resistances were redistributed after adding PAC. The dominant one changed from filtration resistance to cake resistance. These smaller cake resistances resulted from the PAC because, showing in the scanning electron microscopy pictures, it made the cake layer looser and rougher than that on a normal membrane. Meanwhile, the analysis of the membrane eluent showed that the addition of PAC changed the microbial species and its metabolites on the membrane and effectively reduced the adsorption of hydrophilic organic molecules on the membrane surface. Additionally, PAC prevented polypeptide compounds from being trapped inside the pores of membranes, so the cake on the PAC-MBR contaminated membrane surface was easier to scrape off. In the test of cleaning methods, alkaline cleaning removed the most organics from contaminated membranes to restore membrane performance.

Experimental test to evaluate performance of an anaerobic reactor provided with an external membrane unit

1998 ◽  
Vol 38 (8-9) ◽  
pp. 385-392 ◽  
Author(s):  
S. Elmaleh ◽  
L. Abdelmoumni
Keyword(s):  
Membrane Fouling ◽  
Industrial Development ◽  
Particle Deposition ◽  
Membrane Surface ◽  
Cross Flow ◽  
Membrane Unit ◽  
Anaerobic Reactor ◽  
Flux Decline ◽  
Aerobic Reactor ◽  
Sludge Production

The coupling of a wastewater treatment anaerobic reactor with a microfiltration or ultrafiltration membrane is particularly attractive: lower sludge production than in an aerobic reactor, methane production and dissociation of the mean residence times of the different phases. However, the industrial development of such a process is hampered by membrane fouling which can be a result of many causes and require a comprehensive study especially fouling by anaerobic suspensions. In order to simplify the study, the different phases of anaerobic oxidation were separated and this work is focused on the filtration of an anaerobic suspension fed with acetic acid as the sole carbon source at 2 g/l TOC. The effluent quality was excellent without sludge production in spite of large variation of the liquid phase space time. The tested filtration elements were tubular Carbosep membranes. The M14 membrane showed the greatest flux of 120 l/m2 h at 0.5 bar and 25 Pa shear stress and the flux increased to 180 l/m2 h when a baffle was introduced. The main fouling mechanism appears to be the particle deposition on the membrane surface as no flux decline was observed at higher cross-flow velocity.

scholarly journals Studies of polypropylene membrane fouling during microfiltration of broth with Citrobacter freundii bacteria

2015 ◽  
Vol 17 (4) ◽  
pp. 56-64 ◽  
Author(s):  
Marek Gryta ◽  
Marta Waszak ◽  
Maria Tomaszewska
Keyword(s):  
Membrane Fouling ◽  
Membrane Surface ◽  
Transmembrane Pressure ◽  
Citrobacter Freundii ◽  
Permeate Flux ◽  
Process Duration ◽  
Polypropylene Membrane ◽  
Flux Decline ◽  
Cake Layer ◽  
Scanning Electron

Abstract In this work a fouling study of polypropylene membranes used for microfiltration of glycerol solutions fermented by Citrobacter freundii bacteria was presented. The permeate free of C. freundii bacteria and having a turbidity in the range of 0.72–1.46 NTU was obtained. However, the initial permeate flux (100–110 L/m2h at 30 kPa of transmembrane pressure) was decreased 3–5 fold during 2–3 h of process duration. The performed scanning electron microscope observations confirmed that the filtered bacteria and suspensions present in the broth formed a cake layer on the membrane surface. A method of periodical module rinsing was used for restriction of the fouling influence on a flux decline. Rinsing with water removed most of the bacteria from the membrane surface, but did not permit to restore the initial permeate flux. It was confirmed that the irreversible fouling was dominated during broth filtration. The formed deposit was removed using a 1 wt% solution of sodium hydroxide as a rinsing solution.

Impact of Microcystis aeruginosa on membrane fouling in a biologically treated effluent

2011 ◽  
Vol 63 (12) ◽  
pp. 2853-2859 ◽  
Author(s):  
Y. T. Goh ◽  
J. L. Harris ◽  
F. A. Roddick
Keyword(s):  
Microcystis Aeruginosa ◽  
Membrane Fouling ◽  
Early Phase ◽  
Cell Concentration ◽  
Membrane Surface ◽  
Late Phase ◽  
Protective Layer ◽  
Green Algal ◽  
Treated Effluent ◽  
Cake Layer

Microcystis aeruginosa was cultured in biologically treated municipal effluent to simulate blue-green algal bloom conditions in a treatment lagoon. The effect of algae in the early, mid and late phases of growth on membrane fouling, chemical coagulation (alum or aluminium chlorohydrate (ACH)) and hydraulic cleaning on the microfiltration of this effluent was investigated. The effect of M. aeruginosa in the early phase was negligible and gave a similar flux profile and permeate volume to that of effluent alone. The increase in M. aeruginosa concentration for the mid and late phases caused a significant reduction in permeate volume compared with the early phase. Full flux recovery was achieved with an alum dose of 1 mg Al3+ L−1 (early phase) and 10 mg Al3+ L−1 (mid phase), demonstrating that membrane fouling was hydraulically reversible. For the late phase, the highest flux recovery was 89%, which was achieved with an alum dose of 5 mg Al3+ L−1. Higher alum dosages resulted in a reduction in flux recovery. The use of 1.5 µm pre-filtration after alum treatment showed little improvement in water quality but led to a drastic reduction in flux recovery, which was attributed to diminishing the protective layer on the membrane surface, thus enabling internal fouling. The performance of ACH was comparable to alum at low dissolved organic carbon (DOC) and cell concentration, but was not as effective as alum at high DOC and cell concentration due to the formation of more compact ACH flocs, which resulted in a higher cake layer specific resistance, leading to the deterioration of performance.

scholarly journals The Combination of Coagulation and Adsorption for Controlling Ultra-Filtration Membrane Fouling in Water Treatment

Water ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 90 ◽  
Author(s):  
Fan Bu ◽  
Baoyu Gao ◽  
Qinyan Yue ◽  
Caiyu Liu ◽  
Wenyu Wang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Water Treatment ◽  
Natural Organic Matter ◽  
Membrane Fouling ◽  
Membrane Surface ◽  
Filtration Membrane ◽  
Cake Layer ◽  
Ultra Filtration ◽  
The Impact ◽  
Filtration Technology

Ultra-filtration technology has been increasingly used in drinking water treatment due to improvements in membrane performance and lowering of costs. However, membrane fouling is the main limitation in the application of ultra-filtration technology. In this study, we investigated the impact of four different pre-treatments: Coagulation, adsorption, coagulation followed by adsorption (C-A), and simultaneous coagulation and adsorption (C+A), on membrane fouling and natural organic matter removal efficiency. The results showed that adsorption process required a large amount of adsorbent and formed a dense cake layer on the membrane surface leading to severe membrane fouling. Compared to adsorption alone, the coagulation and C-A processes decreased the transmembrane pressure by 4.9 kPa. It was due to less accumulation of particles on the membrane surface. As for water quality, the C-A ultra-filtration process achieved the highest removal efficiencies of natural organic matter and disinfection by-product precursors. Therefore, the addition of adsorbent after coagulation is a potentially important approach for alleviating ultra-filtration membrane fouling and enhancing treatment performance.

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