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Title 40

Displaying title 40, up to date as of 10/07/2026. Title 40 was last amended 10/02/2026.
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Subpart I—Metallurgical Acid Plants Subcategory

§ 421.90 Applicability: Description of the metallurgical acid plants subcategory.

The provisions of this subpart apply to process wastewater discharges resulting from or associated with the manufacture of by-product sulfuric acid at primary copper smelters, primary zinc facilities, primary lead facilities, and primary molybdenum facilities, including any associated air pollution control or gas-conditioning systems for sulfur dioxide off-gases from pyrometallurgical operations.

[49 FR 8811, Mar. 8, 1984, as amended at 50 FR 38342, Sept. 20, 1985]

§ 421.91 Specialized definitions.

(a) Except as provided below, the general definitions, abbreviations, and methods of analysis set forth in 40 CFR part 401 apply to this subpart.

(b) The term product means 100 percent equivalent sulfuric acid, H2 SO4 capacity.

[50 FR 38342, Sept. 20, 1985]

§ 421.92 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 must achieve the following effluent limitations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available (BPT):

Subpart I—Metallurgical Acid Plant

Pollutant or pollutant property BPT effluent limitations
Maximum for any 1 day Maximum for monthly average
mg/kg (pounds per million pounds of 100% sulfuric acid capacity
Cadmium 0.180 0.090
Copper 5.000 2.000
Lead 1.800 0.790
Zinc 3.600 0.900
Fluoride 1 212.800 121.000
Molybdenum 1 40.180 20.790
Total suspended solids 304.000 152.000
pH 2 2
1 For Molybdenum Acid Plants Only.
2 Within the range of 6.0 to 9.0 at all times.

[50 FR 38342, Sept. 20, 1985; 50 FR 52776, Dec. 26, 1985]

§ 421.93 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:

Subpart I—Metallurgical Acid Plant—BAT Effluent Limitations

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/kg (pounds per/million pounds) of 100 pct sulfuric acid capacity
Arsenic 3.550 1.584
Cadmium 0.511 0.204
Copper 3.269 1.558
Lead 0.715 0.332
Zinc 2.605 1.073
Fluoride 1 89.390 50.820
Molybdenum 1 [Reserved] [Reserved].
1 For Molybdenum acid plants only.

[50 FR 38343, Sept. 20, 1985, as amended at 55 FR 31697, Aug. 3, 1990]

§ 421.94 Standards of performance for new sources.

Any new source subject to this subpart shall achieve the following new source performance standards:

Subpart I—Metallurgical Acid Plant—NSPS

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/kg (pounds per/million pounds) of 100 pct sulfuric acid capacity
Arsenic 3.550 1.584
Cadmium 0.511 0.204
Copper 3.269 1.558
Lead 0.715 0.332
Zinc 2.605 1.073
Fluoride 1 89.390 50.820
Molybdenum 1 [Reserved] [Reserved].
Total suspended solids 38.310 30.650
pH (2) (2)
1 For Molybdenum acid plants only.
2 Within the range of 7.5 to 10.0 at all times.

[50 FR 38343, Sept. 20, 1985, as amended at 55 FR 31697, Aug. 3, 1990]

§ 421.95 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 metallurgical acid plant blowdown introduced into a POTW shall not exceed the following values:

Subpart I—Metallurgical Acid Plant—PSES

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/kg (pound per/million pounds) of 100 pct sulfuric acid capacity
Cadmium 0.511 0.204
Zinc 2.605 1.073

[50 FR 38343, Sept. 20, 1985]

§ 421.96 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 metallurgical acid plant blowdown introduced into a POTW shall not exceed the following values:

Subpart I—Metallurgical Acid Plant—PSNS

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/kg (pounds per million pounds) of 100 pct sulfuric acid capacity
Arsenic 3.550 1.584
Cadmium 0.511 0.204
Copper 3.269 1.558
Lead 0.715 0.332
Zinc 2.605 1.073
Fluoride 1 89.390 50.820
Molybdenum 1 [Reserved] [Reserved].
1 For Molybdenum acid plants only.

[50 FR 38343, Sept. 20, 1985, as amended at 55 FR 31697, Aug. 3, 1990]

§ 421.97 [Reserved]