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ABSTRACT: Dyes fouling of reverse osmosis (RO) membranes and its relation to adsorption had been investigated by using a crossflow RO filtration setup. Methylene blue (MB) and rhodamine B (RB) were used as model organic foulants. The calculated amount of the irreversible sorption was related to the irreversible flux decline. The characteristic fouling kinetics was accounted by Langmuir-Hinshelwood (L-H) kinetics model for initial fouling, with the fouling rate constant k=0.0556μm s(-1)min(-1) and k=0.0181μm s(-1)min(-1) for MB and RB fouling RO membrane CPA2, respectively. And the subsequent fouling was attributed to the growth of a dye cake. A remarkable correlation was obtained between the quantified irreversible sorption and irreversible flux decline under the solution chemistries investigated. In the presence of divalent cation, the extent of flux decline was related to the competition model.
Journal of hazardous materials 05/2011; 192(2):490-9. · 4.14 Impact Factor
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ABSTRACT: PURPOSE OF WORK: This study was to demonstrate the degradation effectiveness and application potential of Candida tropicalis JH8. A phenol-degrading yeast was isolated from activated sludge and was identified as C. tropicalis. It used phenol as the sole source of carbon at up to 1,800 mg l(-1). The optimal conditions for phenol degradation were pH 6 at 37 °C with a 2% (v/v) inoculum. Complete degradation of 1,800 mg phenol l(-1) was achieved after 62 h.
Biotechnology Letters 01/2011; 33(5):943-6. · 1.68 Impact Factor
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ABSTRACT: A novel phenol-degrading filamentous fungus, strain JH6, was isolated from activated sludge and identified as a member of Paecilomyces variotii based on standard morphological and phylogenetic analysis. The degradation assays suggested that the strain was able to utilize phenol as the sole source of carbon and energy at concentrations up to 1800 mg/l. The strain exhibited optimum phenol degradation performance with the addition of 100 mg/l glucose at pH 5, 37°C. Haldane's model could be fitted to the growth kinetics data well over a wide range of initial phenol concentrations (100-1800 mg/l), with kinetic values μ(max)=0.312 h(-1), K(s)=130.4 mg/l, and K(i)=200 mg/l. The decay coefficient was found to be 0.0073 h(-1). Complete phenol degradation by strain JH6 could be achieved in the presence of other toxicants, such as m-cresol and quinoline, which were often found in the real phenol-containing wastewater.
Journal of hazardous materials 11/2010; 183(1-3):366-71. · 4.14 Impact Factor
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ABSTRACT: Fatty acid fouling of reverse osmosis (RO) membranes and its relation to adsorption under various chemistries had been investigated by using a crossflow RO filtration setup. Octanoic acid was used as model organic foulant. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was utilized to semi-quantitatively determine the adsorption of the foulants on the membrane surface. The determined adsorption amount was related to the irreversible flux decline. Fouling was more significant at solution chemistries that resulted in larger adsorption amount, namely, lower pH, higher ionic strength and lower temperature. The flux decline increased first with the increasing ionic strength, and then it decreased at the ionic strength 50 mM. The rate and extent of flux decline decreased with the higher Ca2+ concentration due to the decreasing organic compound hydrophobicity. In the presence of magnesium, fouling behavior decreased slightly after the addition of magnesium ion, whereas, flux decline barely changed when Mg2+ concentration was increased gradually. To elucidate mechanisms of membrane fouling more clearly, the Lewis acid–base interfacial free energy was also studied according to the extended Derjaguin–Landau–Verwey–Overbeek (extended DLVO) approach.Graphical abstractWell-controlled fouling–cleaning experiments were conducted to investigate the correlation between the membrane fouling behaviors in terms of flux decline and the adsorption of organic foulants under various solution chemistries. The FTIR spectra of the membranes clearly demonstrated that octanoic acid was readily adsorbed onto the RO membrane and adsorption directly determined the membrane fouling behavior.Research highlights▶ The correlation between the irreversible flux decline and the adsorption of organic foulants was investigated under various solution chemistries though well-controlled fouling–cleaning experiments. ▶ As a result, pretreatment to manipulate solution pH was an effective way to control octanoic fouling, while pretreatment to manipulate solution hardness might not be an effective way.
Separation and Purification Technology 77(1):171-178. · 2.92 Impact Factor
