40 CFR § 421.112 - 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/s421.112"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 421.112 - 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: "421.112"
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"
---


# 421.112 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 technology currently available:

(a) Subpart K—Concentrate Digestion Wet Air Pollution Control.

BPT Effluent Limitations

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/kg (pounds per million pounds) of concentrate digested |  |
| Lead | 2.612 | 1.244 |
| Zinc | 9.080 | 3.794 |
| Ammonia (as N) | 829.000 | 364.500 |
| Fluoride | 217.700 | 124.400 |
| Total suspended solids | 255.000 | 121.300 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(b) Subpart K—Solvent Extraction Raffinate.

BPT Effluent Limitations

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/kg (pounds per million pounds) of concentrate digested |  |
| Lead | 3.888 | 1.851 |
| Zinc | 13.520 | 5.647 |
| Ammonia (as N) | 1,233.000 | 542.500 |
| Fluoride | 324.000 | 185.100 |
| Total Suspended Solids | 379.500 | 189.500 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(c) Subpart K—Solvent Extraction Wet Air Pollution Control.

BPT Effluent Limitations

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/kg (pounds per million pounds) of concentrate digested |  |
| Lead | 1.032 | .491 |
| Zinc | 3.586 | 1.498 |
| Ammonia (as N) | 327.400 | 143.900 |
| Fluoride | 85.960 | 49.120 |
| Total suspended solids | 100.700 | 47.890 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(d) Subpart K—Precipitation and Filtration.

BPT Effluent Limitations

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/kg (pounds per million pounds) of concentrate digested |  |
| Lead | 5.750 | 2.738 |
| Zinc | 19.990 | 8.350 |
| Ammonia (as N) | 1,825.000 | 802.200 |
| Fluoride | 479.100 | 273.800 |
| Total suspended solids | 561.300 | 267.000 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(e) Subpart K—Precipitation and Filtration Wet Air Pollution Control.

BPT Effluent Limitations

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/kg (pounds per million pounds) of concentrate digested |  |
| Lead | 26.680 | 12.700 |
| Zinc | 92.730 | 38.740 |
| Ammonia (as N) | 8,466.000 | 3,722.000 |
| Fluoride | 2,223.000 | 1,270.000 |
| Total suspended solids | 2,604.000 | 1,239.000 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(f) Subpart K—Tantalum Salt Drying.

BPT Effluent Limitations

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/kg (pounds per million pounds) of tantalum salt dried |  |
| Lead | 25.430 | 12.110 |
| Zinc | 88.390 | 36.930 |
| Ammonia (as N) | 8,070.000 | 3,548.000 |
| Fluoride | 2,119.000 | 1,211.000 |
| Total suspended solids | 2,482.000 | 1,181.000 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(g) Subpart K—Oxides Calcining Wet Air Pollution Control.

BPT Effluent Limitations

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/kg (pounds per million pounds) of columbium-tantalum oxide dried |  |
| Lead | 16.140 | 7.685 |
| Zinc | 56.100 | 23.440 |
| Ammonia (as N) | 5,122.000 | 2,252.000 |
| Fluoride | 1,345.000 | 768.500 |
| Total suspended solids | 1,576.000 | 749.200 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(h) Subpart K—Reduction of Tantalum Salt to Metal.

BPT Effluent Limitations

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/kg (pounds per million pounds) of tantalum salt reduced |  |
| Lead | 69.750 | 33.220 |
| Zinc | 242.500 | 101.300 |
| Ammonia (as N) | 22,140.000 | 9,732.000 |
| Fluoride | 5,813.000 | 3,322.000 |
| Total suspended solids | 6,809.000 | 3,239.000 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(i) Subpart K—Reduction of Tantalum Salt to Metal Wet Air Pollution Control.

BPT Effluent Limitations

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/kg (pounds per million pounds) of tantalum salt reduced |  |
| Lead | .858 | .409 |
| Zinc | 2.983 | 1.246 |
| Ammonia (as N) | 272.400 | 119.700 |
| Fluoride | 71.510 | 40.860 |
| Total suspended solids | 83.770 | 39.840 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(j) Subpart K—Tantalum Powder Wash.

BPT Effluent Limitations

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/kg (pounds per million pounds) of tantalum power washed |  |
| Lead | 8.582 | 4.087 |
| Zinc | 29.830 | 12.470 |
| Ammonia (as N) | 2,724.000 | 1,198.000 |
| Fluoride | 715.200 | 408.700 |
| Total suspended solids | 837.800 | 398.500 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(k) Subpart K—Consolidation and Casting Contact Cooling.

BPT Effluent Limitations

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/kg (pounds per million pounds) of columbium or tantalum cast or consolidated |  |
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
| Fluoride | .000 | .000 |
| Total suspended solids | .000 | .000 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

[49 FR 8817, Mar. 8, 1984, as amended at 49 FR 29795, July 24, 1984; 50 FR 12253, Mar. 28, 1985]