Advanced Dynamic Simulation of Membrane Desalination Modules Accounting for Organic Fouling
A reliable dynamic simulator (based on a sound process model) is highly desirable for optimizing the performance of individual membrane modules and of entire desalination plants. This paper reports on progress toward development of a comprehensive model of the complicated physical-chemical processes occurring in spiral wound membrane (SWM) modules, that accounts for the temporal system variability caused by organic membrane fouling. To render the mathematical modeling-problem tractable, justified simplifications (retaining the physical parameter interdependencies) lead to a system of basic equations in two spatial planar coordinates, enabling to obtain a realistic temporal evolution of all process parameters at retentate and permeate flow channels of SWM modules. The developed flexible model structure, and process simulator, allow incorporation of sub-models (for phenomena occurring at small spatial scales during desalination) that account for a) feed-spacer effects on friction losses and mass transfer and b) membrane fouling. These sub-models, in the form of generalized expressions, are obtained for the former case through advanced numerical simulations, and for the latter by correlating experimental data of specific fouling resistance with permeation flux. Typical parametric study results presented herein, for realistic combinations of design and operating system parameters, demonstrate the versatility and reliability of the new model/simulator and its potential to analyze the complicated interaction of mechanisms involved during fouling evolution. The new results warrant further model development that would include other types of fouling and scaling, thus leading to a comprehensive simulator useful for practical applications.