Membrane condenser: technology for water recovery from atmosphere

Nowadays, the availability of potable water has become an environmental issue due to the continuous growth in water demand not balanced by an adequate recharge. Recovery of water from atmosphere and in particular from the waste gaseous streams could become a new water source. In this work, hydrophobic membranes are used in membrane contactor configuration for the selective removal of water from the evaporated industrial "waste". In particular, hydrophobic membranes are utilized in a membrane condenser. In this system, the feed (super-satured industrial gas) is brought into contact with one side (retentate side) of a hydrophobic, microporous membrane. The hydrophobic nature of the membrane prevents the penetration of the liquid into the pores while the gases pass through the membrane. Therefore, the liquid is recovered from the retentate side of the membrane, whereas the dehydrated gases from the permeate side of the membrane. A simulation study of the process has been developed for predicting the membrane-based process performance. The achieved results indicate that feed flow rate Q, interfacial membrane area , the ratio Q/A, the temperature difference (?T) between the fed flue gas and the membrane module are the parameters controlling the process. In particular, the amount of recovered water rises at increasing ?T and Q/A, whereas its quality is made worse at increasing ?T and Q. Moreover, a 20% water recovery (the amount to make the plant self-sufficient) can be achieved with temperature reductions less than 5 °C if flue gas is in common conditions (i.e., 50 °C < T < 90°C and 90% < RH < 100%). The simulation study was validated by an experimental analysis confirming its validity and suitability for a screening of the potentialities offered by the membrane condenser in the dehydration of gaseous streams.