Regulations last checked for updates: May 01, 2025
Title 40 - Protection of Environment last revised: Nov 01, 2025
§ 421.220 - Applicability: Description of the secondary molybdenum and vanadium subcategory.
The provisions of this subpart are applicable to discharges resulting from the production of molybdenum or vanadium by secondary molybdenum and vanadium facilities.
§ 421.221 - Specialized definitions.
For the purpose of this subpart the general definitions, abbreviations, and methods of analysis set forth in 40 CFR part 401 shall apply to this subpart.
§ 421.222 - 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) Leach tailings.
BPT Limitations for the Secondary Molybdenum and Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of technical grade molybdenum plus vanadium plus pure grade molybdenum produced
|
| Arsenic | 40.778 | 18.145
|
| Chromium | 8.585 | 3.512
|
| Lead | 8.195 | 3.902
|
| Nickel | 37.460 | 24.779
|
| Iron | 23.410 | 11.902
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 8078.000 | 3551.000
|
| Total Suspended Solids | 799.950 | 380.460
|
| pH | (
1) | (
1)
|
(b) Molybdenum filtrate solvent extraction raffinate.
BPT Limitations for the Secondary Molybdenum and Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of technical grade molybdenum plus vanadium plus pure grade molybdenum produced
|
| Arsenic | 121.720 | 54.162
|
| Chromium | 25.625 | 10.483
|
| Lead | 24.460 | 11.648
|
| Nickel | 111.819 | 73.964
|
| Iron | 69.887 | 35.526
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 24114.000 | 10600.000
|
| Total Suspended Solids | 2387.800 | 1135.660
|
| pH | (
1) | (
1)
|
(c) Vanadium decomposition wet air pollution control.
BPT Limitations for the Secondary Molybdenum and Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of vanadium produced by decomposition
|
| Arsenic | 0.000 | 0.000
|
| Chromium | 0.000 | 0.000
|
| Lead | 0.000 | 0.000
|
| Nickel | 0.000 | 0.000
|
| Iron | 0.000 | 0.000
|
| Molybdenum | 0.000 | 0.000
|
| Ammonia (as N) | 0.000 | 0.000
|
| Total suspended solids | 0.000 | 0.000
|
| pH | (
1) | (
1)
|
(d) Molybdenum drying wet air pollution control.
BPT Limitations for the Secondary Molybdenum and Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum produced
|
| Arsenic | 0.000 | 0.000
|
| Chromium | 0.000 | 0.000
|
| Lead | 0.000 | 0.000
|
| Nickel | 0.000 | 0.000
|
| Iron | 0.000 | 0.000
|
| Molybdenum | 0.000 | 0.000
|
| Ammonia (as N) | 0.000 | 0.000
|
| Total suspended solids | 0.000 | 0.000
|
| pH | (
1) | (
1)
|
(e) Pure Grade Molybdenum.
BPT Limitations for the Secondary Molybdenum and Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of pure molybdenum produced
|
| Arsenic | 48.655 | 21.650
|
| Chromium | 10.243 | 4.190
|
| Lead | 9.778 | 4.656
|
| Nickel | 44.698 | 29.566
|
| Iron | 27.936 | 14.201
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 9638.000 | 4237.000
|
| Total Suspended Solids | 954.480 | 453.960
|
| pH | (
1) | (
1)
|
§ 421.223 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best available technology economically achievable.
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 available technology economically achievable:
(a) Leach Tailings.
BAT Limitations for the Secondary Molybdenum and Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of technical grade molybdenum plus vanadium plus pure grade molybdenum produced
|
| Arsenic | 27.120 | 12.097
|
| Chromium | 7.219 | 2.927
|
| Lead | 5.463 | 2.536
|
| Nickel | 10.731 | 7.219
|
| Iron | 23.413 | 11.902
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 8078.000 | 3551.000 |
(b) Molybdenum filtrate solvent extraction raffinate.
BAT Limitations for the Secondary Molybdenum and Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of technical grade molybdenum plus vanadium plus pure grade molybdenum produced
|
| Arsenic | 80.952 | 36.108
|
| Chronium | 21.548 | 8.736
|
| Lead | 16.306 | 7.571
|
| Nickel | 32.031 | 21.548
|
| Iron | 69.887 | 35.526
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 24114.000 | 10600.000 |
(c) Vanadium decomposition wet air pollution control.
BAT Limitations for the Secondary Molybdenum and Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of vanadium produced by decomposition
|
| Arsenic | 0.000 | 0.000
|
| Chromium | 0.000 | 0.000
|
| Lead | 0.000 | 0.000
|
| Nickel | 0.000 | 0.000
|
| Iron | 0.000 | 0.000
|
| Molybdenum | 0.000 | 0.000
|
| Ammonia (as N) | 0.000 | 0.000 |
(d) Molybdenum drying wet air pollution control.
BAT Limitations for the Secondary Molybdenum and Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum produced
|
| Arsenic | 0.000 | 0.000
|
| Chromium | 0.000 | 0.000
|
| Lead | 0.000 | 0.000
|
| Nickel | 0.000 | 0.000
|
| Iron | 0.000 | 0.000
|
| Molybdenum | 0.000 | 0.000
|
| Ammonia (as N) | 0.000 | 0.000 |
(e) Pure Grade Molybdenum.
BAT Limitations for the Secondary Molybdenum and Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of pure molybdenum produced
|
| Arsenic | 32.359 | 14.434
|
| Chromium | 8.614 | 3.492
|
| Lead | 6.518 | 3.026
|
| Nickel | 12.804 | 8.614
|
| Iron | 27.936 | 14.201
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 9638.000 | 4237.000 |
§ 421.224 -
Any new source subject to this subpart shall achieve the following new source performance standards:
(a) Leach tailings.
NSPS for the Secondary Molybdenum and Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of technical grade molybdenum plus vanadium plus pure grade molybdenum produced
|
| Arsenic | 27.120 | 12.097
|
| Chromium | 7.219 | 2.927
|
| Lead | 5.463 | 2.536
|
| Nickel | 10.731 | 7.219
|
| Iron | 23.413 | 11.902
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 8078.000 | 3551.000
|
| Total Suspended Solids | 292.665 | 234.132
|
| pH | (
1) | (
1)
|
(b) Molybdenum filtrate solvent extraction raffinate.
NSPS for the Secondary Molybdenum and Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of technical grade molybdenum plus vanadium plus pure grade molybdenum produced
|
| Arsenic | 80.952 | 36.108
|
| Chromium | 21.548 | 8.736
|
| Lead | 16.306 | 7.571
|
| Nickel | 32.031 | 21.548
|
| Iron | 69.887 | 35.526
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 24114.000 | 10600.000
|
| Total Suspended Solids | 873.585 | 698.868
|
| pH | (
1) | (
1)
|
(c) Vanadium decomposition wet air pollution control.
NSPS for the Secondary Molybdenum and Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum and vanadium produced
|
| Arsenic | 0.000 | 0.000
|
| Chromium | 0.000 | 0.000
|
| Lead | 0.000 | 0.000
|
| Nickel | 0.000 | 0.000
|
| Iron | 0.000 | 0.000
|
| Molybdenum | 0.000 | 0.000
|
| Ammonia (as N) | 0.000 | 0.000
|
| Total suspended solids | 0.000 | 0.000
|
| pH | (
1) | (
1)
|
(d) Molybdenum drying wet air pollution control.
NSPS for the Secondary Molybdenum and Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum and vanadium produced
|
| Arsenic | 0.000 | 0.000
|
| Chromium | 0.000 | 0.000
|
| Lead | 0.000 | 0.000
|
| Nickel | 0.000 | 0.000
|
| Iron | 0.000 | 0.000
|
| Molybdenum | 0.000 | 0.000
|
| Ammonia (as N) | 0.000 | 0.000
|
| Total suspended solids | 0.000 | 0.000
|
| pH | (
1) | (
1)
|
(e) Pure Grade Molybdenum.
NSPS for the Secondary Molybdenum and Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of pure molybdenum produced
|
| Arsenic | 32.359 | 14.434
|
| Chromium | 8.614 | 3.492
|
| Lead | 6.518 | 3.026
|
| Nickel | 12.804 | 8.614
|
| Iron | 27.936 | 14.201
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 9638.000 | 4237.000
|
| Total Suspended Solids | 349.200 | 279.360
|
| pH | (
1) | (
1)
|
§ 421.225 - [Reserved]
§ 421.226 - Pretreatment standards for new sources.
Except as provided in 40 CFR 403.7, any new 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 new sources. The mass of wastewater pollutants in secondary molybdenum and vanadium process wastewater introduced into a POTW shall not exceed the following values:
(a) Leach tailings.
PSNS for the Secondary Molybdenum and Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of technical grade molybdenum plus vanadium plus pure grade molybdenum produced
|
| Arsenic | 27.120 | 12.097
|
| Chromium | 7.219 | 2.927
|
| Lead | 5.463 | 2.536
|
| Nickel | 10.731 | 7.219
|
| Iron | 23.413 | 11.902
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 8078.000 | 3551.000 |
(b) Molybdenum filtrate solvent extraction raffinate.
PSNS for the Secondary Molybdenum And Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of technical grade molybdenum plus vanadium plus pure grade molybdenum produced
|
| Arsenic | 80.952 | 36.108
|
| Chromium | 21.548 | 8.736
|
| Lead | 16.306 | 7.571
|
| Nickel | 32.031 | 21.548
|
| Iron | 69.887 | 35.526
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 24114.000 | 10600.000 |
(c) Vanadium decomposition wet air pollution control.
PSNS for the Secondary Molybdenum and Vandadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) vanadium produced by decomposition
|
| Arsenic | 0.000 | 0.000
|
| Chromium | 0.000 | 0.000
|
| Lead | 0.000 | 0.000
|
| Nickel | 0.000 | 0.000
|
| Iron | 0.000 | 0.000
|
| Molybdenum | 0.000 | 0.000
|
| Ammonia (as N) | 0.000 | 0.000 |
(d) Molybdenum drying wet air pollution control.
PSNS for the Secondary Molybdenum and Vandadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum produced
|
| Arsenic | 0.000 | 0.000
|
| Chromium | 0.000 | 0.000
|
| Lead | 0.000 | 0.000
|
| Nickel | 0.000 | 0.000
|
| Iron | 0.000 | 0.000
|
| Molybdenum | 0.000 | 0.000
|
| Ammonia (as N) | 0.000 | 0.000 |
(e) Pure Grade Molybdenum.
PSNS for the Secondary Molybdenum And Vanadium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of pure molybdenum produced
|
| Arsenic | 32.359 | 14.434
|
| Chromium | 8.614 | 3.492
|
| Lead | 6.518 | 3.026
|
| Nickel | 12.804 | 8.614
|
| Iron | 27.936 | 14.201
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 9638.000 | 4237.000 |
§ 421.227 - [Reserved]
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,
c,
e,
and, 1316 (b) and
c, 1317 (b) and
c,
1318; 86 Stat. 816, Pub. L. 92-500; 91 Stat. 1567, Pub. L. 95-217; 101 Stat. 7, Pub. L. 100-4
source: 49 FR 8790, Mar. 8, 1984, unless otherwise noted.
cite as: 40 CFR 421.223