40 CFR 420.135 - Pretreatment standards for existing sources (PSES).
Except as provided in 40 CFR 403.7 and 403.13, any existing source subject to this subpart that introduces pollutants into a publicly owned treatment works must comply with 40 CFR part 403 and must achieve the following pretreatment standards for existing sources (PSES):
(a) Direct-reduced iron. [Reserved]
(b) Forging operations. [Reserved]
(c) Briquetting. There shall be no discharge of process wastewater pollutants to POTWs.