Physicochemical phenomena are well understood and their application in practice is simple, the operation will The effectiveness of a fixed bed operation is depended mainly on its hydraulic performance.
The situation is even difficult considering the scale up difficulties.įrequently, it is not possible to achieve full similarity between different scales. Modeling of the operation a complex task. Parameters and/or solid diffusion coefficients seem to be unexpectedly influenced by contact time, making the Using clinoptilolite, peat and activated carbon respectively, in fixed bed operation, it is found that equilibrium For example, even in the simple cases of Pb2+, Cd2+ and Cu2+ and basic dyes removal from solution Mathematical tools and in many cases, for complicated wastewater, the full modeling of the process is extremelyĭifficult. Systems requires extensive experimental information (laboratory and pilot scale experiments), complex (liquid holdup, geometric analogies and maldistribution) factors. Influenced by equilibrium (isotherm, capacity), kinetic (diffusion and convection coefficients) and hydraulic 2: Breakthrough curve.Īlthough the fixed bed mode is highly useful, its analysis is unexpectedly complex. This information could be derived from experiments conducted in laboratoryĬolumns and the scale up goal is to “transfer” it to large unit or at least to evaluate the changes during scaling.įig. Then, from a practical point of view,īreakpoint volume is the most important information: it is the liquid volume that can be treated by the column Volume) until the column effluent exceeds breakpoint concentration. The main aim when sizing adsorptive columns is the ability to predict the service time (or total effluent BreakpointĬoncentration is a selected limiting value (according to the needs of the treatment) where the operation should be In Figure 2 (C/Co) is the dimensionless exit concentration and (Veff) is the effluent volume. In the following figures a typical column operation and its breakthrough įixed bed is the most frequently used operation for ion exchange and adsorption as is the predominant way ofĬonducting such sorption separations. Removal of heavy metals and several organic substances from wastewaters, as benzene, phenolic compounds,Ĭarbon tetrachloride, nitrophenol, acid dyes and p-dichlorobenzene.
For example, in ionĮxchange processes, zeolites and resins are used for the removal of heavy metals as Pb2+, Cr3+, Fe3+, Cu2+ andĪmmonia while in adsorption processes activated carbon, peat, iron oxide, kaolin and fly ash is used for the Ion exchange and adsorption are common operations used for the wastewater treatment. Key words : ion exchange, adsorption, fixed beds, scale-up Up and approximate design methods are presented. Models and hydraulics of fixed bed operations are presented. Number of experimental data along with some scale-up and hydraulic-performanceĬonsiderations, extracted from the related literature. The methods essentially propose the use of a minimum In the present study – composed by two parts – short cut methods is These effects could be critical not only in full scale but also in pilot or even in Simple, the operation will probably fail if the hydraulic behavior of the reactor is If the physicochemical phenomena are well understood and their application in practice is It is true that the overallĮffectiveness of a fixed bed operation depended mainly on its hydraulic performance. The situation is even more difficultĬonsidering the maldistribution, as well as the scale up procedures. Modeling of the process maybe extremely difficult. Predictive model for fixed bed systems requires extensive experimental information,Ĭomplex mathematical tools and in many cases, for complicated wastewater, the full ION EXCHANGE AND ADSORPTION FIXED BED OPERATIONS FOR WASTEWATER TREATMENT - PART I: MODELING FUNDAMENTALS AND HYDRAULICS ANALYSISĬhemical Engineer (PhD, MSc), SC European Focus Consulting, Bacau, Romania, Fixed bed is the most frequently used operation for ion exchange and adsorptionĪnd although highly useful and utilized, its engineering analysis is quite complex.