Primary surface measurement reported
Contact angle measurements of membranes and mixed liquor suspended solids (MLSS) were conducted to evaluate surface hydrophobicity and fouling characteristics.
Client Citation Analysis
Advanced separation and anaerobic digestion technologies for value-added bioproducts and biofuel from pulp and paper mill wastes
This study investigates hemicellulose extraction from thermomechanical pulp (TMP) mill process water and evaluates biogas production and membrane performance of pulp and paper primary sludge using a thermophilic submerged anaerobic membrane bioreactor, including surface property analysis via Dropometer.
At-a-Glance Summary
Dropometer attribution in the paper
Dropometer (Droplet Lab, Canada) was used to measure contact angles on membranes and MLSS, with analysis including surface characterization and fouling assessment.
How the surface-tension / contact-angle data were used in the study
Contact angle data were applied to correlate surface hydrophobicity with membrane fouling, flux performance, and dewaterability of sludge under varying operating conditions (SRT, HRT, OLR) in the ThSAnMBR.
Replication / reliability statement
Measurements were performed on multiple membrane and MLSS samples; exact replicate counts were not specified in the available text.
Paper Details
Title
Advanced separation and anaerobic digestion technologies for value-added bioproducts and biofuel from pulp and paper mill wastes
Authors
Alnour Mahmmoud Alnour Bokhary
Journal
Thesis, Lakehead University
Year
2021
Pages / Article
246
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What Was Measured
Primary surface / interfacial measurement
Static water contact angle (sessile drop) on PVDF membranes and MLSS aggregates to assess surface hydrophobicity relevant to fouling propensity.
Supporting measurements
Membrane flux, transmembrane pressure, SEM-EDX, FTIR, XPS, and particle size distribution were also analyzed to interpret correlations between surface characteristics and operational performance of the ThSAnMBR.
Role of the Dropometer
The Dropometer was used to measure static contact angles of water droplets on both membrane surfaces and MLSS particles. Contact angles were recorded to assess hydrophobicity changes due to sludge exposure and fouling deposition. These measurements supported analysis of fouling layer formation, membrane performance, and digestate surface properties.
Key Findings
Membrane surface hydrophobicity shifts
Contact angle measurements indicated that the used PVDF membranes developed more hydrophobic surfaces over longer SRTs, consistent with fouling deposition patterns observed in SEM/EDX.
MLSS hydrophobicity correlates with fouling
Higher MLSS contact angles were linked to increased gel-layer formation and membrane resistance, supporting operational data on flux decline.
Operating conditions influence surface properties
Variations in SRT, HRT, and OLR affected membrane and MLSS contact angles, demonstrating the role of process parameters in modifying surface hydrophobicity.
Surface chemistry confirmation
XPS and FTIR data aligned with contact angle measurements, confirming chemical changes (e.g., protein and polysaccharide deposition) on membranes and sludge surfaces.
Figures & Visuals
Figure 5.8 — Membrane surface analysis
What it shows
Shows sessile drop contact angles on PVDF membranes after SRT-dependent operation.
Figure 5.9 — MLSS particle wettability
What it shows
Illustrates water droplet contact angles on mixed liquor solids, supporting correlation with fouling.
Figure 7.6 — Surface morphology plots
What it shows
Depicts 3D plots of membrane surfaces used at different SRTs, supporting the contact angle trends.
Figure 7.10 — XPS vs contact angle
What it shows
Compares elemental composition to measured contact angles for virgin and used membranes.
Why It Matters
Dropometer contact angle measurements enabled a quantitative assessment of surface hydrophobicity changes during anaerobic membrane treatment of pulp and paper mill sludge. These outputs were directly linked to fouling formation, membrane performance, and sludge dewaterability, helping to optimize operational conditions (SRT, HRT, OLR) for stable biogas production and membrane longevity.
Practical Takeaways
Fouling prediction
Contact angle data can be used to anticipate gel layer formation and flux decline.
Operational tuning
Adjusting SRT and OLR influences surface hydrophobicity and membrane performance.
Sludge handling
MLSS hydrophobicity informs downstream dewatering strategies.
Membrane maintenance
Contact angles post-cleaning indicate effectiveness of chemical cleaning protocols.