In this study, the economic feasibility of two novel microwave-regenerated adsorption systems was evaluated by systematically comparing the capital and operating costs of the proposed systems with ten conventional VOC control technologies. The results indicate that under certain conditions microwave regeneration of adsorbent beds offers a cost-effective alternative to conventional VOC recovery (steam or inert gas stripping) and abatement technologies (thermal or catalytic incineration). In particular, it was found that the microwave systems have similar capital and operating costs to conventional steam regeneration systems and, therefore, may present an attractive alternative for recovering water-miscible solvents.
In general, the cost of the microwave subsystem is a relatively small component of the overall system costs and the microwave power requirements are within the range of commercially available generators even for large emission streams. The enhanced heat and mass transfer rates make it considerably more energy efficient than conventional regeneration; even with the higher unit cost of electrical energy, the operating costs are expected to be less than steam or hot-gas stripping. The additional capital costs incurred to generate and deliver the microwaves to the bed would be off-set by a much smaller recovery system and a reduced adsorbent inventory.