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).

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.

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

Three-Dimensional Modeling of an Activated Sludge Floc

Langmuir ◽  
1997 ◽  
Vol 13 (1) ◽  
pp. 35-40 ◽  
Author(s):  
F. Zartarian ◽  
C. Mustin ◽  
G. Villemin ◽  
T. Ait-Ettager ◽  
A. Thill ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Three Dimensional ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling

Comparison of membrane biofouling in nitrification and denitrification for the membrane bioreactor (MBR)

2006 ◽  
Vol 53 (6) ◽  
pp. 43-49 ◽  
Author(s):  
N. Jang ◽  
X. Ren ◽  
K. Choi ◽  
I.S. Kim
Keyword(s):  
Membrane Fouling ◽  
Extracellular Polymeric Substances ◽  
Membrane Pore ◽  
Pore Blocking ◽  
Membrane Biofouling ◽  
Cake Layer ◽  
Layer Resistance ◽  
Nitrification And Denitrification ◽  
Stirred Cell ◽  
Modified Fouling Index

Batch filtration tests were conducted to compare the characteristics of membrane biofouling with regard to nitrification and denitrification. A Modified Fouling Index (MFI) was obtained using a stirred cell tester. The denitrification assays showed higher membrane fouling rates than the nitrification assays.The fouling became worse, not only due to pore blocking resistance, but also from cake layer resistance after denitrification. The Extracellular Polymeric Substances (EPS) concentration and relative hydrophobicity were decreased after denitrification, resulting in floc deterioration. The floc deterioration was assumed to have increased the cake layer resistance in the filtration test. The protein Soluble Microbial Products (SMP) concentration, portion of high molecular weight in carbohydrate SMP and relative hydrophobicity were increased after denitrification, which was assumed to cause membrane pore blocking. The changes in the EPS and SMP characteristics were the main fouling parameters in denitrification.

Comparative experimental study on fouling mechanisms in nano-porous membrane: cheese whey ultrafiltration as a case study

2016 ◽  
Vol 74 (12) ◽  
pp. 2737-2750 ◽  
Author(s):  
Mohammad Torkamanzadeh ◽  
Mohsen Jahanshahi ◽  
Majid Peyravi ◽  
Ali Shokuhi Rad
Keyword(s):  
Membrane Fouling ◽  
Porous Membrane ◽  
Quantitative Prediction ◽  
Layer Formation ◽  
Cake Filtration ◽  
Operational Conditions ◽  
Cake Layer ◽  
Classical Models ◽  
Pore Blockage ◽  
Relative Errors

Determination of fouling mechanisms and accurate quantitative prediction of nano-porous membrane behavior are of great interest in membrane processes. This work has focused on a comprehensive comparison of two classical and new fouling models. Different operational conditions were tested to analyze the level of agreement of these models with experimental observation. Whey solutions of 8, 0.8 and 0.5 g/L were ultrafiltered in transmembrane pressures (TMPs) of 300 and 500 KPa through a synthesized polyethersulfone/copolymer blend membrane. Fouling mechanisms and the effect of different combinations of TMPs and protein concentrations were determined and analyzed by fitting the experimental data to different models. Based on the results obtained from classical models, it was found that the predictions of the cake layer formation model were quite acceptable, followed by the intermediate blocking model. The new combined pore blockage-cake filtration model, however, was found to be very successful in predicting the flux decline over time for every operational condition tested, with all relative errors of prediction less than 5%. The latter also showed a good performance in the transition from the pore blockage mechanism to cake layer formation.

scholarly journals Investigation of membrane fouling mechanism of intracellular organic matter during ultrafiltration

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Weiwei Huang ◽  
Yuanhong Zhu ◽  
Bingzhi Dong ◽  
Weiwei Lv ◽  
Quan Yuan ◽  
...  
Keyword(s):  
Organic Matter ◽  
Chlorella Vulgaris ◽  
Membrane Fouling ◽  
Membrane Surface ◽  
Layer Formation ◽  
Fouling Control ◽  
Fouling Mechanism ◽  
Cake Layer ◽  
Severe Degree ◽  
Filtration Flux

AbstractThis study investigated the ultrafiltration (UF) membrane fouling mechanism of intracellular organic matter (IOM) from Chlorella vulgaris (CV) and Microcystis aeruginosa (MA). Both CV- and MA-IOM caused severe membrane fouling during UF; however, there were significant differences in the membrane fouling by these two materials. Neutral hydrophilic (N-HPI) compounds were the organics that caused the most severe membrane fouling during CV-IOM filtration, whereas the MA-IOM membrane fouling was induced by mainly hydrophobic (HPO) organics. From an analysis based on Derjaguin–Landau–Verwey–Overbeek theory, it was found that the interaction energy between the membrane and foulants in the later stage of filtration was the major factor determining the efficiency of filtration for both CV-IOM and MA-IOM. The TPI organics in CV-IOM fouled the membrane to a more severe degree during the initial filtration flux; however, when the membrane surface was covered with CV-IOM foulants, the N-HPI fraction of CV-IOM caused the most severe membrane fouling because its attractive energy with the membrane was the highest. For MA-IOM, regardless of the initial filtration flux or the late stage of filtration, the HPO organics fouled the membrane to the greatest extent. An analysis of modified filtration models revealed that cake layer formation played a more important role than other fouling mechanisms during the filtration of CV-IOM and MA-IOM. This study provides a significant understanding of the membrane fouling mechanism of IOM and is beneficial for developing some strategies for membrane fouling control when treating MA and CV algae-laden waters.

Extracellular polymeric substances' influence on membrane fouling and cleaning during microfiltration process

2006 ◽  
Vol 6 (1) ◽  
pp. 141-148 ◽  
Author(s):  
C. Nuengjamnong ◽  
J. Cho ◽  
C. Polprasert ◽  
K.-H. Ahn
Keyword(s):  
Activated Sludge ◽  
Membrane Fouling ◽  
Extracellular Polymeric Substances ◽  
Positive Influence ◽  
Cleaning Efficiency ◽  
Chemical Cleaning ◽  
Submerged Membrane Bioreactor ◽  
Cake Layer ◽  
Solids Retention ◽  
Specific Cake Resistance

In this study, the influence of extracellular polymeric substances (EPS) on membrane fouling and cleaning efficiency was investigated during the microfiltration process of a submerged membrane bioreactor (SMBR). Two lab-scale SMBRs with different solids retention time (SRT) were operated and the variation of bound (or extractable) EPS in the activated sludge floc was observed in terms of total organic carbon and protein concentration of the extracted EPS solution. Experimental results showed that as SRT decreases, the amount of bound EPS in the activated sludge floc becomes higher. EPS had a positive influence on specific cake resistance to accelerate the membrane fouling. In order to clean the fouled membrane, de-ionized water flushing, chemical cleaning using sodium hypochlorite (NaOCl), and the combination of water flushing and chemical cleaning were performed. The flux recovery rate was calculated to quantify the cleaning efficiency and a microscopic image using scanning electron microscopy was taken to visualize the cleaning effect. It was found that the water flushing was not highly effective at removing the EPS formed in the cake layer. The chemical cleaning of membrane by 5,000 ppm NaOCl for 3 hours could be more effective to eliminate EPS.

BIM and GIS integration for infrastructure analysis

2021 ◽  
Author(s):  
Alessandro Di Benedetto ◽  
Salvatore Barba ◽  
Margherita Fiani ◽  
Marco Limongiello ◽  
Anna Sanseverino
Keyword(s):  
Structural Model ◽  
Semantic Representation ◽  
Local Level ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Information Modeling ◽  
Geodetic Reference System ◽  
Strong Impact ◽  
Campania Region ◽  
Three Dimensional Modeling

<p>The use of Building Information Modeling (BIM) is certainly increasing, especially in the field of Civil Engineering and Architecture. In recent years, research for new solutions has focused on the integration of BIM and GIS (Geographic Information System), referred to as GeoBIM. Most applications focus on issues related to the import and interoperability of BIM data into a GIS environment and vice versa. Data integration in a well-designed GeoBIM should address the following aspects: i) data harmonization and consistency (e.g., accuracy estimation, geometric and semantic representation, amount of detail, geo-referencing); ii) interoperability of data coming from different sources; iii) transformation of a set of data into a standardized format. One of the most evident inconsistencies if working with BIM or GIS is in the georeferencing of data: BIM designers work in a local Cartesian system while the terrain morphology is referred to a Geodetic Reference System, in the case of Europe, and therefore also for Italy, such system is the ETRS89, realization ETRF2000. The objective of this work is to achieve a true integration between BIM and GIS through the use and combination of the strengths of both technologies: the semantic and spatial component of GIS with the 3D and detailed information coming from the BIM model. A model that meets these requirements will allow a management of the structure and / or infrastructure in a wider and more complete context; therefore, not only at the local level but will be applicable to structures that have a strong impact with the territory and located in areas subject to hydrogeological risk. One of the innovative aspects of the study is the integration of the regional Topographic Database (TDB) with the altimetric component extracted automatically from LiDAR data; the process aims to allow the reconstruction of the volumes in an automated way of each object to define the 3D spatial attribute for the purposes of three-dimensional modeling. The study area is located near the “Monti Lattari” in the Campania Region, in southern Italy. The whole area consists of areas exposed to high hydrogeological risk, characterized by the presence of a complex infrastructural network (railway, highway, national and provincial roads), rich in viaducts, tunnels and galleries. In details, the GeoBIM model of a viaduct (Olivieri Viaduct), built between the years ‘50 and ‘60, has been made. The main structure is a Maillart-arch-type bridge, made of reinforced concrete with a continuous frame deck and two access viaducts. The structural model has been generated from the point cloud acquired by Terrestrial Laser Scanner (TLS). The BIM model has been realized by using Revit software package (Autodesk), which allowed to organize the information useful to define the entire viaduct: each virtual element has been “informed” with all the parameters and characteristics of the structural elements. The next work phase was addressed to the design of a workflow able to combine the BIM model into a GIS developed by using ESRI tools. So, the parametric model produced in Revit is transformed into a GeoDatabase.</p>

Using magnetic powder to enhance coagulation membrane filtration for treating micro-polluted surface water

2015 ◽  
Vol 16 (1) ◽  
pp. 104-114 ◽  
Author(s):  
Jie Wang ◽  
Lulu Liu ◽  
Jun Yang ◽  
Sasa Yang ◽  
Hongwei Zhang ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Surface Water ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Layer Structure ◽  
Three Dimensional ◽  
Magnetic Powder ◽  
Enhanced Coagulation ◽  
Cake Layer ◽  
High Fractal Dimension

The magnetic enhanced coagulation membrane filtration (MECMF) process was introduced into micro-polluted surface water treatment. The process was conducted by adding magnetic powder (MP) for enhancing coagulation. By contrasting the water quality parameters including dissolved organic carbon (DOC), UV254 and turbidity of permeates of MECMF and coagulation/flocculation membrane filtration (CFMF), results showed that the removal efficiency in the MECMF process was higher than those in the CFMF process. According to normalized flux and resistance analysis, membrane flux declined relatively slow and irreversible fouling resistance was lesser in the MECMF process. By analyzing the three-dimensional fluorescence of permeates and raw water, it was clearly shown that the permeate quality of the MECMF process was superior to that of the CFMF process apparently, which highlighted the removal of protein-like substances was more effectively in MECMF. Furthermore, the addition of MP could provide Lorentz and magnetic dipole forces between colloidal matters during coagulation, leading to the increase of collision frequency and efficiency and the formation of large size flocs with high fractal dimension. Large and high fractal dimension flocs could form a porous cake layer, which could increase water permeability. On the basic of the above findings, it was suggested that magnetic-enhanced coagulation that promoted flocs to develop could regulate cake layer structure and mitigate membrane fouling to some extent.

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