U of S | Mailing List Archive | alt-photo-process-l | Re: I have a question

Re: I have a question

In my understanding the limit of around 1 mg/liter is a very
common limit at the point of entry to the sewer system. I do
understand that the waste gets diluted very rapidly but that's
not a factor incorporated in regulation. Regardless, this is a
regulatory matter and whether I feel safe/ethical to continue
to use ferricyanide for b&w bleach is a different issue. I
think it's best to convince photographic chemical retail
businesses to offer better alternatives.

Ryuji Suzuki

From: Liam Lawless <lawless@bulldoghome.com>
Subject: RE: I have a question
Date: Sun, 21 Oct 2007 15:54:33 +0100

> Your figures re. pot. ferri. dilution are alarming, but at
> what point should the concentration be 1 p.p.m. - when it
> enters the drainage system, when it finally reached the
> treatment facility, or somewhere in between?  Won't it also
> be diluted by waste water from other sources?