Modeling of pore blocking and cake layer formation in membrane filtration for wastewater treatment

Desalination ◽  
2006 ◽  
Vol 189 (1-3) ◽  
pp. 97-109 ◽  
Author(s):  
A. Broeckmann ◽  
J. Busch ◽  
T. Wintgens ◽  
W. Marquardt
Keyword(s):  
Wastewater Treatment ◽  
Membrane Filtration ◽  
Layer Formation ◽  
Pore Blocking ◽  
Cake Layer

Organic colloids and their influence on low-pressure membrane filtration

2004 ◽  
Vol 50 (12) ◽  
pp. 311-316 ◽  
Author(s):  
C. Laabs ◽  
G. Amy ◽  
M. Jekel
Keyword(s):  
Wastewater Treatment ◽  
Glass Fiber ◽  
Membrane Filtration ◽  
Membrane Surface ◽  
Treatment Plant ◽  
Low Pressure ◽  
Colloidal Solutions ◽  
Cake Layer ◽  
Stirred Cell ◽  
Macromolecular Component

Wastewater treatment by low-pressure membrane filtration (MF and UF) is affected to a large extent by macromolecules and colloids. In order to investigate the influence of organic colloids on the membrane filtration process, colloids were isolated from a wastewater treatment plant effluent using a rotaryevaporation pre-concentration step followed by dialysis. Stirred cell tests were carried out using redissolved colloids, with and without additional glass fiber filtration. After constant pressure membrane filtration of 190 L/m2, the initial flux had declined by 50% for colloids > 6-8 kD (glass fiber filtered) with a hydrophilic MF membrane and for colloids >12-14 kD (glass fiber filtered) with a hydrophobic MF membrane. For the non-filtered colloidal solutions, the flux decline was even steeper with the flux being below 10% of the initial flux after 190 L/m2 were passed through the membranes. As with larger particles, colloids form a filtration cake layer on top of the membrane surface when used as isolates without prior filtration. This filtration cake is easily removed during backwashing. However, polysaccharides as a macromolecular component of the colloid isolate cause severe fouling by the formation of a gel layer on the membrane surface that is difficult to remove completely.

Integrating activated sludge floc size information in MBR fouling modeling

2015 ◽  
Vol 71 (7) ◽  
pp. 1073-1080 ◽  
Author(s):  
T. A. Cao ◽  
G. Van De Staey ◽  
I. Y. Smets
Keyword(s):  
Activated Sludge ◽  
Membrane Fouling ◽  
Three Dimensional ◽  
Strong Impact ◽  
Layer Formation ◽  
Floc Size ◽  
Pore Blocking ◽  
Three Dimensional Modeling ◽  
Cake Layer ◽  
Floc Size Distributions

Although studied extensively, modeling fouling phenomena in membrane bioreactors (MBRs) remains challenging. It has been well established that cake layer formation and pore blocking have a strong impact on the filtration performance but how to capture that in comprehensive models is not fully defined yet. Since it has been shown that bioflocculation characteristics of activated sludge have a clear link with (the extent of) membrane fouling, this study integrates activated sludge floc size (i.e., particle size distribution) information in the model for pore blocking and cake layer formation with a focus on constant flux operated MBRs. Based on these floc size distributions, a three-dimensional modeling and visualization of the cake layer is envisaged which can then provide the required input information (e.g., the porosity of the cake layer) for the fouling model. The model is calibrated and validated on the basis of experimental data from Hwang et al. (2012) in ‘Membrane bioreactor: TMP rise and characterization of biocake structure using CLSM-image analysis’ (see J. Membr. Sci. 419–420, 33–41).

Effect of membrane characteristics on the performance of membrane bioreactors for oily wastewater treatment

2011 ◽  
Vol 64 (5) ◽  
pp. 1154-1160 ◽  
Author(s):  
S. Mafirad ◽  
M. R. Mehrnia ◽  
M. H. Sarrafzadeh
Keyword(s):  
Wastewater Treatment ◽  
Pore Size ◽  
Oxygen Demand ◽  
Oily Wastewater ◽  
Layer Formation ◽  
Submerged Membrane Bioreactor ◽  
Working Volume ◽  
Cake Layer ◽  
Oily Wastewater Treatment

Influence of membrane material and pore size on the performance of a submerged membrane bioreactor (sMBR) for oily wastewater treatment was investigated. The sMBR had a working volume of about 19 L with flat sheet modules at the same hydrodynamic conditions. Five types of micro- and ultra-polymeric membranes containing cellulose acetate (CA), cellulose nitrate (CN), polyamide (PA), polyvinylidene difluoride (PVDF) and polyethersulfone (PES) were used and their filtration performance in terms of permeability, permeate quality and fouling intensity were evaluated. Characterization of the membranes was done by performing some analysis such as pore size distribution; contact angle and scanning electronic microscopy (SEM) microphotograph on all membranes. The quality of permeates from each membrane was identified by measuring chemical oxygen demand (COD). The results showed more irreversible fouling intensity for membranes with larger pore size which can be due to more permeation of bioparticles and colloids inside the pores. Membrane characteristics have a major role in the preliminary time of the filtration before cake layer formation so that the PA with the highest hydrophilicity had the lowest permeability decline by fouling in this period. Also, the PVDF and PES membranes had better performance according to better permeate quality in the preliminary time of the filtration related to smaller pore size and also their better fouling resistance and chemical stability properties. However, all membranes resulted in the same permeability and permeate quality after cake layer formation. An overall efficiency of about 95% in COD removal was obtained for oily wastewater treatment by the membranes used in this study.

Kinetic analysis of PAC cake-layer formation in hybrid PAC-MF systems

2008 ◽  
Vol 8 (1) ◽  
pp. 1-7 ◽  
Author(s):  
S. Takizawa ◽  
P. Zhao ◽  
S. Ohgaki ◽  
H. Katayama
Keyword(s):  
Membrane Filtration ◽  
Specific Resistance ◽  
Experimental Studies ◽  
Ceramic Membranes ◽  
Layer Formation ◽  
Void Space ◽  
Filtration Resistance ◽  
Saw Dust ◽  
Cake Layer ◽  
The Difference

Experimental studies were conducted to evaluate the effectiveness of backwashing and air-scouring to prevent cake-layer formation on the membranes in a hybrid PAC-MF process. The membrane filtration chamber used in this study was separated into two zones; namely, the PAC adsorption zone (PAZ) and the membrane filtration zone (MFZ). In MFZ tubular ceramic membranes were installed, and powdered activated carbon (PAC) was suspended in PAZ at a concentration of 20 g/L by aeration. Air-scouring and backwashing rates were gradually increased to see if these physical cleaning measures can reduce or maintain the filtration resistance due to formation of PAC cake layer on the membrane. Two types of saw-dust PAC having different sizes were used to find the difference of the effects of air-scouring and backwashing. A smaller PAC (Shirasagi C1, Japan EnviroChemicals, Co.) showed a slower increasing rate of filtration resistance than the larger PAC (Shirasagi S-10, Japan EnviroChemicals, Co.). It was found that air-scouring didn't reduce the rate of cake fouling formation of PAC S-10, but can quite effectively reduce the rate of PAC C-1 attachment to the membrane. On the contrary, backwashing was not effective for PAC C-1, but quite effective for PAC S-10. PAC C1 formed a porous cake with low specific resistance, which can be easily removed by air-scouring, but cannot be removed by backwashing. On the other hand, PAC S-10 formed a tight cake layer because suspended particles get in to the void space between the PAC S-10. A dynamic model was proposed to explain the effect of air-scouring and backwashing to removal cake layer from the membranes.

scholarly journals Tanning Wastewater Treatment by Ultrafiltration: Process Efficiency and Fouling Behavior

Membranes ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 461
Author(s):  
Fu Yang ◽  
Zhengkun Huang ◽  
Jun Huang ◽  
Chongde Wu ◽  
Rongqing Zhou ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Shear Rate ◽  
Membrane Surface ◽  
Filtration Efficiency ◽  
Operating Conditions ◽  
Process Efficiency ◽  
Transmembrane Pressure ◽  
Leather Industry ◽  
Pore Blocking ◽  
The Impact

Ultrafiltration is a promising, environment-friendly alternative to the current physicochemical-based tannery wastewater treatment. In this work, ultrafiltration was employed to treat the tanning wastewater as an upstream process of the Zero Liquid Discharge (ZLD) system in the leather industry. The filtration efficiency and fouling behaviors were analyzed to assess the impact of membrane material and operating conditions (shear rate on the membrane surface and transmembrane pressure). The models of resistance-in-series, fouling propensity, and pore blocking were used to provide a comprehensive analysis of such a process. The results show that the process efficiency is strongly dependent on the operating conditions, while the membranes of either PES or PVDF showed similar filtration performance and fouling behavior. Reversible resistance was the main obstacle for such process. Cake formation was the main pore blocking mechanism during such process, which was independent on the operating conditions and membrane materials. The increase in shear rate significantly increased the steady-state permeation flux, thus, the filtration efficiency was improved, which resulted from both the reduction in reversible resistance and the slow-down of fouling layer accumulate rate. This is the first time that the fouling behaviors of tanning wastewater ultrafiltration were comprehensively evaluated, thus providing crucial guidance for further scientific investigation and industrial application.

scholarly journals Gravity-Driven Membrane Reactor for Decentralized Wastewater Treatment: Effect of Reactor Configuration and Cleaning Protocol

Membranes ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 388
Author(s):  
Ihtisham Ul Haq Shami ◽  
Bing Wu
Keyword(s):  
Wastewater Treatment ◽  
Municipal Wastewater ◽  
Economic Feasibility ◽  
Reactor Configuration ◽  
Membrane Performance ◽  
Decentralized Wastewater Treatment ◽  
Water Head ◽  
Cake Layer ◽  
Gravity Driven ◽  
Cleaning Protocol

In this study, three gravity-driven membrane (GDM) reactors with flat sheet membrane modules and various biocarriers (synthetic fibers, lava stones, and sands) were operated for municipal wastewater treatment. The effects of water head, periodically cleaning protocol, and operation temperature on the GDM reactor performance were illustrated in terms of membrane performance and water quality. The results indicated that: (1) the cake layer fouling was predominant (>~85%), regardless of reactor configuration and operation conditions; (2) under lower water head, variable water head benefited in achieving higher permeate fluxes due to effective relaxation of the compacted cake layers; (3) the short-term chemical cleaning (30–60 min per 3–4 days) improved membrane performance, especially when additional physical shear force was implemented; (4) the lower temperature had negligible effect on the GDM reactors packed with Icelandic lava stones and sands. Furthermore, the wastewater treatment costs of the three GDM reactors were estimated, ranging between 0.31 and 0.37 EUR/m3, which was greatly lower than that of conventional membrane bioreactors under lower population scenarios. This sheds light on the technical and economic feasibility of biocarrier-facilitated GDM systems for decentralized wastewater treatment in Iceland.

scholarly journals The role of wastewater treatment plants in surface water contamination by plastic pollutants

2018 ◽  
Vol 45 ◽  
pp. 00054 ◽  
Author(s):  
Bozena Mrowiec
Keyword(s):  
Wastewater Treatment ◽  
Surface Water ◽  
Water Contamination ◽  
Membrane Filtration ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Point Sources ◽  
Municipal Sewage ◽  
Municipal Wastewater Treatment ◽  
Surface Water Contamination

The aim of this paper was to review the literature data regarding the physico-chemical characteristic of plastic pollutants discharged with municipal sewage, the practical possibility of removing microplastic particles from wastewater during different treatment steps in WWTPs and the problem of surface water contamination within them. Microplastics (the size range of 1 nm to < 5 mm), have been recognized as an emerging threat, as well as an ecotoxicological and ecological risk for water ecosystems. Municipal wastewater treatment plants (WWTPs) are mentioned as the main point sources of microplastics in an aquatic environment. Microplastic particles can be effectively removed in the primary treatment zones via solids skimming and sludge settling processes. Different tertiary treatment processes such as: gravity sand filtration, discfilter, air flotation and membrane filtration provide substantial additional removal of microplastics, and the efficiency of wastewater treatment process can be at a removal level of 99.9%. Nevertheless, given the large volumes of effluent constantly discharged to receivers, even tertiary level WWTPs may constitute a considerable source of microplastics in the surface water.

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