کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
635628 1456101 2011 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Modeling cake filtration under coupled hydraulic, electric and osmotic effects
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی تصفیه و جداسازی
پیش نمایش صفحه اول مقاله
Modeling cake filtration under coupled hydraulic, electric and osmotic effects
چکیده انگلیسی

Pore blocking is considered to dominate the dewatering efficiency in filtration processes. Various engineering measures were adopted to promote the permeate flux of membrane filtration, e.g. electro-osmosis, flocculation and aggregation, membrane flush and pressure adjustment. A new model was proposed to address the coupling effect of hydraulic, electric and osmotic fields on cake filtration on the basis of thorough review on relevant researches. A moving boundary was configured to evaluate the time-dependent cake growth behavior. An instant mass balance was assumed valid at the cake–slurry interface, which was shown to reflect the experimental facts. The coupled governing equations were solved numerically by finite element method (FEM), and were validated by comparing with experimental results. The nonlinear constitutive behaviors of the filter cake under varied pressure head were further included in the models. FEM analysis indicates that the hydraulic conductivity and electro-osmotic coefficient of the formed cake are critical for the permeation flux. Correspondingly the pressure head and electrical potential gradient applied to the filtration system largely determine the separation efficiency. The filter cake (FC) formed in front of membrane filter contributes a lot to the reduction in solvent flux under certain dewatering conditions. Measures to improve the flocculation behavior of dispersible sludge were explained by the new model. Modifying the surface charge of sludge with polyelectrolyte is found to benefit the dewatering only within a limited time/leachate range, which was reported for the first time. Suggestions on cake filtration were provided according to our numerical simulations.


► A new model was proposed to address the coupling effect of hydraulic, electrical and osmotic fields on cake filtration.
► Hydraulic conductivity and electro-osmotic constant proved to be the key factors that influence the cake filtration.
► Flocculating agents that modify the surface charge of suspended particles could enhance the permeation flux during cake filtration within a limited time range. A threshold value in leachate volume was numerically observed according to our modeling results.
► Suggestions on membrane separation were provided according to our numerical simulations.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Membrane Science - Volume 378, Issues 1–2, 15 August 2011, Pages 485–494
نویسندگان
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