Primary surface measurement reported
Sessile-drop contact angle (CA) measurements using a water droplet were used to evaluate surface hydrophilicity of mixed liquor and membrane samples.
Client Citation Analysis
Membrane performance evaluation and residual fouling characterization in a thermophilic submerged AnMBR treating pulp and paper primary sludge at varying solids retention times
This study evaluates thermophilic submerged AnMBR membrane performance and residual fouling across solids retention times (SRTs) and uses sessile-drop contact angle measurements to track membrane surface wettability changes.
At-a-Glance Summary
Dropometer attribution in the paper
CA measurements were conducted employing a “droplet sessile CA method (Droplet Smart Tech Inc., Markham, ON, Canada).”
How the surface-tension / contact-angle data were used in the study
Contact angle changes were used to compare employed membranes versus unused membranes under different SRTs and to support interpretation of SRT-linked changes in membrane surface properties during sludge digestion.
Replication / reliability statement
Both the mixed liquor and membrane samples underwent triplicate analyses, with subsequent computation of average values.
Paper Details
Title
Membrane performance evaluation and residual fouling characterization in a thermophilic submerged AnMBR treating pulp and paper primary sludge at varying solids retention times
Authors
Alnour Bokhary; Mathew Leitch; Baoqiang Liao
Journal
Separation and Purification Technology
Year
2025
Volume
358
Pages / Article
130438
License
© 2024 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Journal context
What it is
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How to read it
Compare metrics within category; updates are annual and lag current-year publications.
Scopus metrics (Elsevier / Scopus rating 2024)
CiteScore 2024
15.1
CiteScore subject ranks (CiteScore 2024)
Q1 - Chemistry: Analytical Chemistry (7/160) Q1 - Chemical Engineering: Filtration and Separation (3/19)
SNIP 2024
1.383
SJR 2024
1.697
Journal Impact Factor (Clarivate JCR)
Journal Impact Factor (JCR 2024)
9.0
5-Year Impact Factor
JCR category rank
Q1 - ENGINEERING, CHEMICAL (16/176)
What Was Measured
Primary surface / interfacial measurement
Contact angle (CA) measurements were performed using a sessile droplet method with a 3 μL water droplet to determine surface hydrophilicity.
Supporting measurements
Surface characterization included FTIR for residual foulants, SEM/EDX for membrane morphology and elemental composition, and XPS for elemental composition/chemical state/surface characteristics. The study also reports zeta potential (mixed liquor supernatants), SEM-image-derived surface roughness (Ra, Rq) and pore size distribution (ImageJ-based analysis), SEM texture analysis (Gwyddion), and particle size distribution (laser diffraction).
Role of the Dropometer
Contact angle measurements were conducted employing a droplet sessile CA method (Droplet Smart Tech Inc., Markham, ON, Canada) using a 3 μL water droplet to determine surface hydrophilicity; mixed liquor and membrane samples underwent triplicate analyses with average values computed.
In the results and discussion, the contact angle outputs support comparisons of employed versus unused membranes across SRT conditions and are used in the interpretation of membrane surface-property changes during sludge digestion.
Key Findings
SRT-linked contact angle decreases on employed membranes
Compared to unused membranes, contact angles of employed membranes decreased by 20% (32-day SRT), 24% (45-day SRT), and 39% (55-day SRT).
Statistically significant effect of SRT on contact angle
The authors report that solids retention time significantly impacted contact angle values (p < 0.01).
Wettability change used in residual-fouling interpretation
The authors state that the contact angle change indicates wettability of the employed membrane declined during sludge digestion, and they discuss wettability deterioration in relation to membrane fouling resistance and performance.
Figures & Visuals
Figure 2 — Performance context for residual fouling comparisons
What it shows
Shows permeability of pristine membranes and employed membrane after physical/chemical cleaning and reports membrane resistances under different SRTs.
Figure 3 — Structural change context accompanying surface-property shifts
What it shows
Illustrates pore size distribution comparisons between used and pristine membranes, supporting the membrane surface-property narrative used alongside wettability discussion.
Figure 6 — Residual foulant chemistry used to interpret surface-property changes
What it shows
Presents FTIR spectra for pristine and used membranes and discusses band intensity differences across SRT conditions.
Figure 7 — Morphology and surface-texture visuals tied to membrane surface characterization
What it shows
Provides SEM images and surface textures of virgin and used membranes under different SRTs after physical and chemical cleaning.
Why It Matters
Within the paper’s residual-fouling characterization workflow, contact angle measurements provide a surface-property indicator that is used alongside morphology (SEM) and surface chemistry (FTIR/XPS) to compare membrane condition across operating SRTs.
The study uses these wettability-linked outputs to support its interpretation that membrane surface properties evolve during sludge digestion and to connect surface-property changes with fouling resistance and membrane performance under different SRT conditions.
Practical Takeaways
Defined sessile-drop CA settings
A 3 μL water droplet was used for contact angle measurements, with triplicate analyses and averaging reported for mixed liquor and membrane samples.
SRT comparison is built into the CA reporting
Contact angle changes are reported as percent decreases for employed membranes versus unused membranes at 32-, 45-, and 55-day SRT conditions.
CA is positioned as part of a multi-technique surface characterization set
Contact angle measurements are presented alongside SEM/EDX, FTIR, XPS, and SEM-image-based roughness/pore metrics in the residual fouling characterization workflow.
Statistical support accompanies the CA trend
The authors report a significant SRT effect on contact angle (p < 0.01), supporting comparisons across operating conditions.