Quote Originally Posted by Leigh B View Post
When you compare the small amount of hca used with the dramatic decrease in the volume of wash water used,
the environmental impact balance is strongly in favor of hca.

- Leigh

Go here for the MSDS of HCA : https://www2.itap.purdue.edu/msds/docs/9725.pdf

The working solution is up to 50 g/l Na2SO3 which has a very high COD. It ranks up there with some developers and near or below hypo itself! I don't deny it is useful, but rather I argue that if you dump a 1 L tray, you have to contend with normal hypo/silver in wash #1, HCA that you dumped, and HCA / silver in wash #2. It is the hca dumped and wash #2 that I am pointing to. These must be at least handled properly.