40 CFR § 439.36
Pretreatment standards for existing sources (PSES)
June 9, 2020
Except as provided in 40 CFR 403.7 and 403.13, any existing source subject to this subpart must continue achieving the standards for cyanide specified in paragraph (b) of this section and must achieve the standards specified in §439.16(a) by September 21, 2001.
(a) Sources that discharge to a POTW with nitrification capability (defined at §439.1(i)) are not required to achieve the standards for ammonia (as N).
(b) The standards for cyanide are the same as specified in §439.12(e), (f) and (g).
[68 FR 12274, Mar. 13, 2003]