The bromoil bleach/tan formula that I use calls for 30 mls of a 1% solution of pot. dichchromate (along with 70 mls of a 10% soluton of copper sulphate and 70 mls of a 10% solution of pot. bromide) that is further diluted with 1000 mls of distilled water for a working solution. I discussed the disposal of this bleach with the proper folks in my county. I was told that the dichromate is so dilute and is in such small quantities, to put it down the drain and not to be concerned. That's what I do.