Depending on the application, H&T uses the packed tower forced draft or vacuum degasifier design to strip CO2, VOCs and other gases. The towers are circular and typically made of FRP for forced draft or steel construction for vacuum applications. They can be supplied with an integral clearwell or can sit above an existing below-grade clearwell. A polypropylene packing is used based on volume calculations to produce the required surface area. Various sizes and shapes of packing media are available, and selection would depend on job-specific requirements.
Influent water is sprayed on the packing at the top of the tower, and as the water cascades down through the packing, forms a film on its surface facilitating the release of entrained gases into the counter-current flow of air passing up through the tower. In a forced draft application, a low-pressure high-volume fan pushes air up through the tower and a demister removes water droplets from the air, which exit the tower through a vent. In a Vacuum degasifier application, there is a process connection at the top of the tower allowing the Vacuum pump to withdraw air. Performance is dependent on the water temperature and concentration of gases. The depth of packing, size and type of packing and air volume can all be adjusted to meet any requirements.