---
kind: "section"
citation: "40 C.F.R. § 421.256"
title: "40"
number: "421.256"
heading: "Pretreatment standards for new sources."
url: "https://uscodex.org/cfr/40/421.256"
---

# §421.256. Pretreatment standards for new sources.


Except as provided in [40 CFR 403.7](/cfr/40/403.7.md), any new source subject to this subpart which introduces pollutants into a publicly owned treatment works must comply with [40 CFR part 403](/cfr/40/part403.md) and achieve the following pretreatment standards for new sources. The mass of wastewater pollutants in primary precious metals and mercury process wastewater introduced into a POTW shall not exceed the following values:

- (a) **Smelter wet air pollution control.**
- (b) **Silver chloride reduction spent solution.**
- (c) **Electrolytic cells wet air pollution control.**
- (d) **Electrolyte preparation wet air pollution control.**
- (e) **Calciner wet air pollution control.**
- (f) **Calcine quench water.**
- (g) **Calciner stack gas contact cooling water.**
- (h) **Condenser blowdown.**
- (i) **Mercury cleaning bath water.**

## Notes

### Source

Source: 50 FR 38361, Sept. 20, 1985, unless otherwise noted.

### Authority

Authority: Secs. 301, 304 (b), (c), (e), and (g), 306 (b) and (c), 307 (b) and (c), 308 and 501 of the Clean Water Act (the Federal Water Pollution Control Act Amendments of 1972, as amended by the Clean Water Act of 1977) and the Water Quality Act of 1987 (the “Act”); 33 U.S.C. 1311, 1314 (b), (c), (e), and (g), 1316 (b) and (c), 1317 (b) and (c), 1318 and 1361; 86 Stat. 816, Pub. L. 92-500; 91 Stat. 1567, Pub. L. 95-217; 101 Stat. 7, Pub. L. 100-4.

### Source

Source: 49 FR 8790, Mar. 8, 1984, unless otherwise noted.