Bob, CCHT stands for Certified Clinical Hemodialysis Technician/Technologist. It is a certification patient care staff need to get and can test for after 6 months on the job. In CT it allows a pct to administer heparin, sub-q lidocaine, CVC care. It does free up nurses from running over to give saline and heparin "pushes" or having to be assigned all the cath pts. I've never heard of it being used for Machine/equipment techs.
I don't know why anyone is sweating about taking the test. I didn't even study for it and the night before drank a bottle of crown. I had a killer hangover and still made the highest grade of everyone that took it in our clinic.
Majority of the questions are clinical, info that you should have learned or know by working on the floor. There are just a few on the water system, reuse, and technical. It you would like to futher your knowledge I would recommend getting the book Hemodialysis for Nurses and Dialysis Personnel, this book has alot of good info.
I recently took the Bonnet exam, and I must say it was quite easy if you know what you are doing and review the Core Curriculum for the Dialysis Tech which a link has been posted to here a few times. I also purchased the secret study guide which was just ok, but in my mind a complete waste of money. The test did not have anything on it we should not know in performing our job.