40 CFR § 421.142 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available.

---
identifier: "/us/cfr/t40/s421.142"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 421.142 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available."
title_number: 40
title_name: "Protection of Environment"
section_number: "421.142"
section_name: "Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available."
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"
---


# 421.142 Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available.

Except as provided in 40 CFR 125.30 through 125.32, any existing point source subject to this subpart shall achieve the following effluent limitations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available:

(a) Sodium Antimonate Autoclave Wastewater.

BPT Limitations for the Primary Antimony Subcategory

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/kg (pounds per million pounds) of antimony contained in sodium antimonate product |  |
| Antimony | 44.840 | 20.000 |
| Arsenic | 32.650 | 14.530 |
| Mercury | 3.906 | 1.562 |
| Total suspended solids | 640.600 | 304.700 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(b) Fouled anolyte.

BPT Limitations for the Primary Antimony Subcategory

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/kg (pounds per million pounds) of antimony metal produced by electrowinning |  |
| Antimony | 44.840 | 20.000 |
| Arsenic | 32.650 | 14.530 |
| Mercury | 3.906 | 1.562 |
| Total suspended solids | 640.600 | 304.700 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(c) Cathode Antimony Wash Water.

BPT Limitations for the Primary Antimony Subcategory

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/kg (pounds per million pounds) of antimony metal produced by electrowinning |  |
| Antimony | 89.680 | 40.000 |
| Arsenic | 65.310 | 29.060 |
| Mercury | 7.812 | 3.125 |
| Total suspended solids | 1,281.000 | 609.300 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |