Title: Fouling behavior and foulant characteristics of reverse osmosis membranes for treated secondary effluent reclamation
Journal: Journal of Membrane Science
Authors: Yan Zhaoa, Lianfa Songb, Say Leong Onga
Corresponding author: Say Leong Ong
Institute:
a Division of Environmental Science & Engineering, National University of Singapore, 10 Kent Ridge Crescent, 119260 Singapore, Singapore
b Department of Civil and Environmental Engineering, Texas Tech University, 10th and Akron, Lubbock, TX 79409, USA
The original and creativity of paper: This study point out the method to characterize the fouling layer on a RO membrane fed with full-scale UF filtered secondary effluent for reclamation by conducting well-controlled laboratory-scale fouling experiments. For each experiment, the organic and inorganic constituents of the fouling layer and accompanying changes in membrane surface morphology and chemistry were analyzed and correlated to the fouling behaviors observed. Finally, fouling mechanisms could be elucidated based on experimental results and data from feed water quality analysis.
Summary: The study operate laboratory-scale cross-flow RO membrane test unit to observe fouling behavior at different recovery. Feed water in this study was UF pre-filtered secondary effluent collected from a local water reclamation plant employing a dual-membrane UF-RO system and UV disinfection technology to produce high-quality reclaimed water. A polyamide thin film composite (PA-TFC)
RO membranes were support by AG, GE Infrastructure Water Process and Technologies, USA).
The summary of results is explained following;
1. More rapid flux decline and poor fouling reversibility were observed when recovery was above a critical value for both fouling experiments at different initial fluxes.
2. There was a remarkable correlation between the different fouling behaviors observed and the characteristics of fouling layers developed.
3. At lower recovery of 55%, organic fouling by carbohydrates and protein-like matters was principally responsible for the flux decline.
4. At a higher recovery of 70%,
a. The formation of a thicker and irreversible composite fouling layer was promoted from the deposition of organic foulants together with inorganic precipitation.
b. The major precipitates (i.e., calcium phosphate and calcium carbonate) most likely formed via bulk crystallization as confirmed by concentrate particle counting and size distribution analysis.
c. An increasing permeates recovery as well as significantly increasing organic fouling enhanced organic deposition on membrane surface.
d. Hydrophobic property and less negatively charged were introduced to membrane surface, which led to further accelerate the fouling development.
Contribution to ESEL:
This study gave an ideas and systematically methods to identify fouling mechanisms. Moreover, research was point out another key which play an important role for fouling formation (i.e., recovery rate). Based on this information, it leads the reviewer in the right track of research about fouling behavior and mechanisms detection.
Reviewed by Monruedee Moonkhum
Email: moon@gist.ac.kr
