Several applications of modular shell and tube polyphosphazene coated membrane units are reported in this paper. These modules were used to measure the mixed-gas separation properties of poly[bis(phenoxy)phosphazene] based polymers on a larger scale. Transport behavior was determined using the variable volume technique. The test gas mixture was SO2/N-2 at temperatures between 80 degrees C and 270 degrees C. Transport of these gases was found to be a sorption controlled process. Several organic-aqueous and organic-organic separations have been performed using the polyphosphazene coated shell and tube modules. The separations include : methylene chloride/water, acetic acid/water, isopropyl alcohol/water, glycerol/water, and hexane/soy oil. The membranes were prepared using slip casting techniques. The results of these studies show that polyphosphazene membranes can effectively be used to separate acid gases acid organic chemicals from various waste streams in harsh, chemically aggressive environments.