Ultrafiltration of biologically treated domestic wastewater: How membrane properties influence performance

In this study, the impact of membrane properties on membrane fouling and permeate water quality was investigated. Short- and long-term laboratory scale experiments using four commercially available hollow fiber UF membranes were performed to study the impact of membrane properties on reversible and irreversible fouling. No significant differences in terms of permeate quality (i.e. biopolymer rejection) were observed over the four tested membranes. It was found that membrane characteristics including pore size, pore distribution and especially materials had a strong impact on the filtration performances in terms of both reversible and irreversible fouling. The short-term filtration tests showed that due to its specific hydrodynamic condition only the inside-out mode UF membrane was subjected to irreversible fouling. These data demonstrate the importance of membrane selection with appropriate operating conditions for optimum performances. The added value of membrane characterization to lab-scale filtration tests for membrane performance was discussed. © 2014 Elsevier B.V. All rights reserved

Characterization of secondary treated effluents for tertiary membrane filtration and water recycling

This study evaluates the impacts of water quality from three different secondary effluents on low pressure membrane fouling. Effluent organic matter (EfOM) has been reported by previous studies as responsible for membrane fouling. However, the contribution of the different components of EfOM to membrane fouling is still not well understood. In order to improve and optimize treatment processes, characterization and quantification of the organic matter are important. The characterization methods used in this study are liquid chromatography coupled with an organic detector (LC-OCD) and excitation emission matrix fluorescence spectroscopy (EEM). A bench-scale hollow fibre membrane system was used to identify the type of fouling depending on the feed water quality. Results showed no measurable dissolved organic carbon removal by the membranes for the three secondary effluents. Biopolymers and humic-like substances found in different proportions in the three effluents were partially retained by the membranes and were identified to contribute significantly to the flux decline of the low pressure membranes. The observed fouling was determined to be reversible by hydraulic backwashing for two effluents and only by chemical cleaning for the third effluent. © IWA Publishing 2012

Impact of effluent organic matter on low-pressure membrane fouling in tertiary treatment

This study aims at comparing low-pressure membrane fouling obtained with two different secondary effluents at bench and pilot-scale based on the determination of two fouling indices: the total fouling index (TFI) and the hydraulically irreversible fouling index (HIFI). The main objective was to investigate if simpler and less costly bench-scale experimentation can substitute for pilot-scale trials when assessing the fouling potential of secondary effluent in large scale membrane filtration plants producing recycled water. Absolute values for specific flux and total fouling index for the bench-scale system were higher than those determined from pilot-scale, nevertheless a statistically significant correlation (r(2) = 0.63, α = 0.1) was obtained for the total fouling index at both scales. On the contrary no such correlation was found for the hydraulically irreversible fouling index. Advanced water characterization tools such as excitation-emission matrix fluorescence spectroscopy (EEM) and liquid chromatography with organic carbon detection (LC-OCD) were used for the characterization of foulants. On the basis of statistical analysis, biopolymers and humic substances were found to be the major contribution to total fouling (r(2) = 0.95 and r(2) = 0.88, respectively). Adsorption of the low molecular weight neutral compounds to the membrane was attributed to hydraulically irreversible fouling (r(2) = 0.67)