(516g) Removal and Recovery of Ammonia from Dilute Aqueous Process/Effluent Streams

There are many effluent/process streams containing a significant amount of ammonia. Current processes to remove and recover this ammonia involve packed tower stripping of this ammonia into air and its reabsorption in a second packed tower into say, a sulfuric acid stream to produce for example, ammonium sulfate. An improved compact membrane-based process has become commercial for some time without using packed towers. In such a process, microporous gas-filled hydrophobic hollow fiber membrane-based modules are used to strip ammonia from the aqueous solution on one side of the hollow fiber membrane and then reabsorb it into a sulfuric acid solution on the other side of the membrane. There is no current published model to describe the performance of such a process in a large module and thereby design such modules. We will describe our activities and results to achieve these goals. In order to carry out such a process, usually the feed solution pH is raised significantly by caustic addition. Alternative membrane-based processes will also be described in this presentation.