I believe Carrier built some of the air washers during that time. Buffalo Forge was another if I'm not mistaken.
My guess is they used city water for whatever cooling effect was achieved, and just let the water run down the drain. This was fairly common back then.
If you get the opportunity...
Depending on your requirements, the systems are custom engineered to meet the demands. I've worked on several of these; sewage effluent to space heating (~140F water) and just finishing up one for 170F water supply.
These are essentially a "regular" refrigeration system, using a refrigerant...