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Role of Reverse Divalent Cation Diffusion in Forward Osmosis Biofouling
Ming Xie1,2, Edo Bar-Zeev1,3, Sara M Hashmi1
1Department of Chemical and Environmental Engineering Yale University , New Haven, Connecticut 06520-8286, United States.
Environmental Science & Technology
|October 28, 2015
Summary
Reverse calcium diffusion significantly worsens forward osmosis (FO) biofouling by altering biofilm structure and composition. This calcium-induced biofouling is linked to extracellular polymeric substances (EPS) complexation, unlike magnesium permeation.
Area of Science:
- Membrane Science
- Environmental Microbiology
- Biotechnology
Background:
- Forward osmosis (FO) is a promising membrane technology.
- Biofouling remains a significant challenge in FO systems.
- Understanding cation diffusion's role in biofouling is crucial for FO performance.
Purpose of the Study:
- To investigate the impact of reverse divalent cation diffusion on FO biofouling.
- To compare the effects of calcium (Ca2+) and magnesium (Mg2+) on biofouling.
- To elucidate the mechanism by which cations influence biofilm formation.
Main Methods:
- Simulated FO biofouling using Pseudomonas aeruginosa on polyamide membranes.
- Utilized MgCl2 and CaCl2 as draw solutions.
- Analyzed water flux decline, biofilm architecture, and composition.
- Employed dynamic and static light scattering, and transmission electron microscopy (TEM).
Main Results:
- Reverse calcium diffusion caused more severe water flux decline than magnesium.
- Calcium permeation altered biofilm architecture, forming thicker, denser extracellular polymeric substances (EPS).
- Calcium ions complexed with EPS, increasing their hydrodynamic radius and altering their shape.
Conclusions:
- Reverse calcium diffusion significantly enhances FO biofouling compared to magnesium.
- Calcium-induced biofouling is attributed to the complexation of Ca2+ with bacterial EPS.
- This finding provides insights into mitigating biofouling in FO systems.
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