40 CFR § 421.295 - Pretreatment standards for existing sources.
---
identifier: "/us/cfr/t40/s421.295"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 421.295 - Pretreatment standards for existing sources."
title_number: 40
title_name: "Protection of Environment"
section_number: "421.295"
section_name: "Pretreatment standards for existing sources."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "N"
subchapter_name: "EFFLUENT GUIDELINES AND STANDARDS"
part_number: "421"
part_name: "NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
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."
regulatory_source: "49 FR 8790, Mar. 8, 1984, unless otherwise noted."
cfr_part: "421"
---
# 421.295 Pretreatment standards for existing sources.
Except as provided in 40 CFR 403.7 and 403.13, any existing source subject to this subpart which introduces pollutants into a publicly owned treatment works must comply with 40 CFR part 403 and achieve the following pretreatment standards for existing sources. The mass of wastewater pollutants in secondary tin process wastewater introduced into a POTW must not exceed the following values:
(a) Tin smelter SO<sub>2</sub> scrubber.
PSES for the Secondary Tin Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/kg (pounds per million pounds) of crude tapped tin produced | |
| Arsenic | 12.790 | 5.703 |
| Lead | 2.575 | 1.196 |
| Iron | 11.040 | 5.611 |
| Tin | 3.495 | 2.024 |
(b) Dealuminizing rinse.
PSES for the Secondary Tin Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/kg (pounds per million pounds) of dealuminized scrap produced | |
| Lead | 0.010 | 0.005 |
| Cyanide (total) | 0.007 | 0.003 |
| Fluoride | 1.225 | 0.697 |
| Tin | 0.013 | 0.008 |
(c) Tin mud acid neutralization filtrate.
PSES for the Secondary Tin Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/kg (pounds per million pounds) of neutralized dewatered tin mud produced | |
| Lead | 1.413 | 0.656 |
| Cyanide (total) | 1.009 | 0.404 |
| Fluoride | 176.600 | 100.400 |
| Tin | 1.918 | 1.110 |
(d) Tin hydroxide wash.
PSES for the Secondary Tin Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/kg (pounds per million pounds) of tin hydroxide washed | |
| Lead | 3.347 | 1.554 |
| Cyanide (total) | 2.391 | 0.956 |
| Fluoride | 418.400 | 237.900 |
| Tin | 4.542 | 2.630 |
(e) Spent electrowinning solution from new scrap.
PSES for the Secondary Tin Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/kg (pounds per million pounds) of cathode tin produced | |
| Lead | 4.704 | 2.184 |
| Cyanide (total) | 3.360 | 1.344 |
| Fluoride | 588.000 | 334.300 |
| Tin | 6.384 | 3.696 |
(f) Spent electrowinning solution from municipal solid waste.
PSES for the Secondary Tin Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/kg (pounds per million pounds) of MSW scrap used as raw material | |
| Lead | 0.033 | 0.015 |
| Cyanide (total) | 0.024 | 0.010 |
| Fluoride | 4.165 | 2.368 |
| Tin | 0.045 | 0.026 |
(g) Tin hydroxide supernatant from scrap.
PSES for the Secondary Tin Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/kg (pounds per million pounds) of tin metal recovered from scrap | |
| Lead | 15.580 | 7.233 |
| Cyanide (total) | 11.130 | 4.451 |
| Fluoride | 1,947.000 | 1,107.000 |
| Tin | 21.140 | 12.240 |
(h) Tin hydroxide supernatant from plating solutions and sludges.
PSES for the Secondary Tin Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/kg (pounds per million pounds) of tin metal recovered from plating solutions and sludges | |
| Lead | 32.20 | 14.95 |
| Cyanide (total) | 23.00 | 9.20 |
| Fluoride | 4,025.00 | 2,289.00 |
| Tin | 43.70 | 25.30 |
(i) Tin hydroxide filtrate.
PSES for the Secondary Tin Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/kg (pounds per million pounds) of tin metal produced | |
| Lead | 7.012 | 3.256 |
| Cyanide (total) | 5.009 | 2.004 |
| Fluoride | 876.500 | 498.400 |
| Tin | 9.517 | 5.510 |