Regulations last checked for updates: May 01, 2025
Title 40 - Protection of Environment last revised: Nov 01, 2025
§ 421.210 - Applicability: Description of the primary molybdenum and rhenium subcategory.
The provisions of this subpart are applicable to discharges resulting from the production of molybdenum and rhenium facilities.
§ 421.211 - 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.
§ 421.212 - 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 limitation representing the degree of effluent reduction attainable by the application of the best practicable technology currently available:
(a) Molybdenum sulfide leachate.
BPT Limitations for the Primary Molybdenum Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum sulfide leached
|
| Arsenic | 0.968 | 0.431
|
| Lead | 0.195 | 0.093
|
| Nickle | 0.889 | 0.588
|
| Selenium | 0.570 | 0.255
|
| Molybdenum | [Reserved] | [Reserved].
|
| Ammonia (as N) | 61.720 | 27.130
|
| Fluoride | 16.210 | 9.214
|
| Total suspended solids | 18.980 | 9.029
|
| pH | (
1) | (
1)
|
(b) Roaster SO2 scrubber.
BPT Limitations for the Primary Molybdenum and Rhenium Subcategory
| Pollutant of pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum sulfide roasted
|
| Arsenic | 3.509 | 1.561
|
| Lead | 0.705 | 0.336
|
| Nickel | 3.224 | 2.133
|
| Selenium | 2.065 | 0.924
|
| Molybdenum | [Reserved] | [Reserved].
|
| Ammonia (as N) | 223.800 | 98.390
|
| Fluoride | 58.770 | 33.410
|
| Total suspended solids | 68.840 | 32.740
|
| pH | (
1) | (
1)
|
(c) Molybdic oxide leachate.
BPT Limitations for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum contained in molybdic oxide leached
|
| Arsenic | 24.210 | 10.770
|
| Lead | 4.865 | 2.317
|
| Nickel | 22.240 | 14.710
|
| Selenium | 14.250 | 6.371
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 1,544.000 | 678.800
|
| Fluoride | 405.400 | 230.500
|
| Total suspended solids | 474.900 | 225.900
|
| pH | (
1) | (
1)
|
(d) Hydrogen reduction furnace scrubber.
BPT Limitations for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum metal powder produced
|
| Arsenic | 47.860 | 21.300
|
| Lead | 9.617 | 4.580
|
| Nickel | 43.970 | 29.080
|
| Selenium | 28.170 | 12.600
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 3,052.000 | 1,342.000
|
| Fluoride | 801.400 | 455.700
|
| Total suspended solids | 938.800 | 446.500
|
| pH | (
1) | (
1)
|
(e) Depleted rhenium scrubbing solution.
BPT Limitations for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum sulfide roasted
|
| Arsenic | 1.497 | 0.666
|
| Lead | 0.301 | 0.143
|
| Nickel | 1.375 | 0.909
|
| Selenium | 0.881 | 0.394
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 95.440 | 41.960
|
| Fluoride | 25.060 | 14.250
|
| Total suspended solids | 29.360 | 13.960
|
| pH | (
1) | (
1)
|
§ 421.213 - 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) Molybdenum sulfide leachate.
BAT Limitations for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds million pounds) of molybdenum sulfide leached
|
| Arsenic | 0.644 | 0.287
|
| Lead | 0.130 | 0.060
|
| Nickel | 0.255 | 0.171
|
| Selenium | 0.380 | 0.171
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 61.720 | 27.130
|
| Fluoride | 16.210 | 9.214 |
(b) Roaster SO2 scrubber.
BAT Limitations for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per/million pounds) of molybdenum sulfide roasted
|
| Arsenic | 2.334 | 1.041
|
| Lead | 0.470 | 0.218
|
| Nickel | 0.924 | 0.621
|
| Selenium | 1.377 | 0.621
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 223.800 | 98.390
|
| Fluoride | 58.770 | 33.410 |
(c) Molybdic oxide leachate.
BAT Limitations for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per/million pounds) of molybdenum contained in molybdic oxide leached
|
| Arsenic | 16.100 | 7.182
|
| Lead | 3.244 | 1.506
|
| Nickel | 6.371 | 4.286
|
| Selenium | 9.499 | 4.286
|
| Molybdenum | [Reserved] | [Reserved]
|
| Ammonia (as N) | 1,544.000 | 678.800
|
| Fluoride | 405.400 | 230.500 |
(d) Hydrogen reduction furnace scrubber.
BAT Limitations for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per/million pounds) of molybdenum metal powder produced
|
| Arsenic | 3.183 | 1.420
|
| Lead | 0.641 | 0.298
|
| Nickel | 1.260 | 0.847
|
| Selenium | 1.878 | 0.847
|
| Molybdenum | [Reserved] | [Reserved].
|
| Ammonia (as N) | 305.300 | 134.200
|
| Fluoride | 80.150 | 45.570 |
(e) Depleted rhenium scrubbing solution.
BAT Limitations for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per/million pounds) of molybdenum sulfide roasted
|
| Arsenic | 0.995 | 0.444
|
| Lead | 0.201 | 0.093
|
| Nickel | 0.394 | 0.265
|
| Selenium | 0.587 | 0.265
|
| Molybdenum | [Reserved] | [Reserved].
|
| Ammonia (as N) | 95.440 | 41.960
|
| Fluoride | 25.060 | 14.250 |
§ 421.214 - Standards of performance for new sources.
Any new source subject to this subpart shall achieve the following new source performance standards:
(a) Molybdenum sulfide leachate.
NSPS for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum sulfide leached
|
| Arsenic | 0.644 | 0.287
|
| Lead | 0.130 | 0.060
|
| Nickel | 0.255 | 0.171
|
| Selenium | 0.380 | 0.171
|
| Molybdenum | [Reserved] | [Reserved].
|
| Ammonia (as N) | 61.720 | 27.130
|
| Fluoride | 16.210 | 9.214
|
| Total suspended solids | 6.945 | 5.556
|
| pH | (
1) | (
1)
|
(b) Roaster SO2 scrubber.
NSPS for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum sulfide roasted
|
| Arsenic | 2.334 | 1.041
|
| Lead | 0.470 | 0.218
|
| Nickel | 0.924 | 0.621
|
| Selenium | 1.377 | 0.621
|
| Molybdenum | [Reserved] | [Reserved].
|
| Ammonia (as N) | 223.800 | 98.390
|
| Fluoride | 58.770 | 33.410
|
| Total suspended solids | 25.190 | 20.150
|
| pH | (
1) | (
1)
|
(c) Molybdic oxide leachate.
NSPS for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum contained in molybdic oxide leached
|
| Arsenic | 16.100 | 7.182
|
| Lead | 3.244 | 1.506
|
| Nickel | 6.371 | 4.286
|
| Selenium | 9.499 | 4.286
|
| Molybdenum | [Reserved] | [Reserved].
|
| Ammonia (as N) | 1,544.000 | 678.800
|
| Fluoride | 405.400 | 230.500
|
| Total suspended solids | 173.800 | 139.000
|
| pH | (
1) | (
1)
|
(d) Hydrogen reduction furnace scrubber.
NSPS for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum metal powder produced
|
| Arsenic | 3.183 | 1.420
|
| Lead | 0.641 | 0.298
|
| Nickel | 1.260 | 0.847
|
| Selenium | 1.878 | 0.847
|
| Molybdenum | [Reserved] | [Reserved].
|
| Ammonia (as N) | 305.300 | 134.200
|
| Fluoride | 80.150 | 45.570
|
| Total suspended solids | 34.350 | 27.480
|
| pH | (
1) | (
1)
|
(e) Depleted rhenium scrubbing solution.
NSPS for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum sulfide roasted
|
| Arsenic | 0.995 | 0.444
|
| Lead | 0.201 | 0.093
|
| Nickel | 0.394 | 0.265
|
| Selenium | 0.587 | 0.265
|
| Molybdenum | [Reserved] | [Reserved].
|
| Ammonia (as N) | 95.440 | 41.960
|
| Fluoride | 25.060 | 14.250
|
| Total suspended solids | 10.740 | 8.592
|
| pH | (
1) | (
1)
|
§ 421.215 - [Reserved]
§ 421.216 - 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 primary molybdenum and rhenium process wastewater introduced into a POTW shall not exceed the following values:
(a) Molybdenum sulfide leachate.
PSNS for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum sulfide leached
|
| Arsenic | 0.644 | 0.287
|
| Lead | 0.130 | 0.060
|
| Nickel | 0.255 | 0.171
|
| Selenium | 0.380 | 0.171
|
| Molybdenum | [Reserved] | [Reserved].
|
| Ammonia (as N) | 61.720 | 27.130
|
| Fluoride | 16.210 | 9.214 |
(b) Roaster SO2 scrubber.
PSNS for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum sulfide roasted
|
| Arsenic | 2.334 | 1.041
|
| Lead | 0.470 | 0.218
|
| Nickel | 0.924 | 0.621
|
| Selenium | 1.377 | 0.621
|
| Molybdenum | [Reserved] | [Reserved].
|
| Ammonia (as N) | 223.800 | 98.390
|
| Fluoride | 58.770 | 33.410 |
(c) Molybdic oxide leachate.
PSNS for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum contained in molybdic oxide leached
|
| Arsenic | 16.100 | 7.182
|
| Lead | 3.244 | 1.506
|
| Nickel | 6.371 | 4.286
|
| Selenium | 9.499 | 4.286
|
| Molybdenum | [Reserved] | [Reserved].
|
| Ammonia (as N) | 1,544.000 | 678.800
|
| Fluoride | 405.400 | 230.500 |
(d) Hydrogen reduction furnace scrubber.
PSNS for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum metal powder produced
|
| Arsenic | 3.183 | 1.420
|
| Lead | 0.641 | 0.298
|
| Nickel | 1.260 | 0.847
|
| Selenium | 1.878 | 0.847
|
| Molybdenum | [Reserved] | [Reserved].
|
| Ammonia (as N) | 305.300 | 134.200
|
| Fluoride | 80.150 | 45.570 |
(e) Depleted rhenium scrubbing solution.
PSNS for the Primary Molybdenum and Rhenium Subcategory
| Pollutant or pollutant property
| Maximum for any 1 day
| Maximum for monthly average
|
|---|
| mg/kg (pounds per million pounds) of molybdenum sulfide roasted
|
| Arsenic | 0.995 | 0.444
|
| Lead | 0.201 | 0.093
|
| Nickel | 0.394 | 0.265
|
| Selenium | 0.587 | 0.265
|
| Molybdenum | [Reserved] | [Reserved].
|
| Ammonia (as N) | 95.440 | 41.960
|
| Fluoride | 25.060 | 14.250 |
§ 421.217 - [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 421.210