Simulation of pervaporation-based hybrid processes to recover organic compounds from waste water

Hybrid-processes combining pervaporation with a conventional separation process to recover organic compounds from waste water has been critically reviewed. Previous research which focused primarily on hydrophobic pervaporation combined with either adsorption, liquid-liquid phase separation, or reverse osmosis showed that these processes offered significant advantages over the exclusive use of just one of the processes involved. It has been discovered that hybrid-processes could often achieve separations more economically than conventional alternatives. In order to explore further benefits of hybrid processes and to create more efficient process combinations, tools must be provided which allow the design of pervaporation units in combination with other separation processes. An effective way to simulate such hybrid processes is to combine a simulation of a pervaporation unit with an existing simulation package which allows one to describe the conventional processes. In this study the pervaporation process simulation is based on an extended ‘resistance-in-series model’ by taking process conditions, membrane properties and module geometric into account. Based on this, the membrane area of the pervaporation unit is divided into small segments and the mass, concentration and energy balance for each of these elements are solved. The permeate and retentate stream for each element is estimated. The process parameters of the final permeate and retentate stream of the pervaporation unit are thus derived for further analysis. This simulation is used in a case study for the removal of pyridine to illustrate the influence of various process parameters on the pervaporation process. The data collected for the pervaporation unit is combined with results for the conventional processes. As a result, the hybrid processes is optimised and compared against conventional waste water treatment alternatives. According to the results obtained pervaporation-based hybrid processes appear to be a viable method of recovering organic compounds from waste water.