['Water Programs']
['Water Quality', 'Point Sources']
02/03/2025
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§421.30 Applicability: Description of the secondary aluminum smelting subcategory.
The provisions of this subpart are applicable to discharges resulting from the recovery, processing, and remelting of aluminum scrap to produce metallic aluminum alloys.
§421.31 Specialized definitions.
For the purpose of this subpart:
(a) Except as provided below, the general definitions, abbreviations and methods of analysis set forth in part 401 of this chapter shall apply to this subpart.
(b) The term product shall mean hot aluminum metal.
(c) At-the-source means at or before the commingling of delacquering scrubber liquor blowdown with other process or nonprocess wastewaters.
§421.32 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) The following limitations establish the quantity or quality of pollutants or pollutant properties, which may be discharged by a point source subject to the provisions of this subpart and which uses water for metal cooling, after application of the best practicable control technology currently available: There shall be no discharge of process wastewater pollutants to navigable waters.
(b) The following limitations establish the quantity or quality of pollutants or pollutant properties which may be discharged by a point source subject to the provisions of this subpart and which uses aluminum fluoride in its magnesium removal process (“demagging process”), after application of the best practicable control technology currently available: There shall be no discharge of process wastewater pollutants to navigable waters.
(c) The following limitations establish the quantity or quality of pollutants or pollutant properties controlled by this section, which may be discharged by a point source subject to the provisions of this subpart and which uses chlorine in its magnesium removal process, after application of the best practicable control technology currently available:
| Effluent characteristic | Average of daily values for 30 consecutive days shall not exceed - |
|---|---|
| Metric units (kilograms per 1,000 kg magnesium removed) | |
| TSS | 175 |
| COD | 6.5 |
| pH | ( 1) |
| 1 Within the range of 7.5 to 9.0. | |
(d) The following limitations establish the quantity or quality of pollutants or pollutant properties which may be discharged by a point source subject to the provisions of this subpart and which processes residues by wet methods, after application of the best practical control technology currently available:
| Effluent characteristic | Average of daily values for 30 consecutive days shall not exceed - |
|---|---|
| Metric units (kilograms per 1,000 kg of product) | |
| TSS | 1.5 |
| Fluoride | 0.4 |
| Ammonia (as N) | 0.01 |
| Aluminum | 1.0 |
| Copper | 0.003 |
| COD | 1.0 |
| pH | ( 1) |
| 1 Within the range of 7.5 to 9.0. | |
§421.33 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) Subpart C - Scrap Drying Wet Air Pollution Control.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pound's per million pounds) of aluminum scrap dried | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Aluminum | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
(b) Subpart C - Scrap Screening and Milling.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pound's per million pounds) of aluminum scrap screened and milled | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Aluminum | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
(c) Subpart C - Dross Washing.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pound's per million pounds) of dross washed | ||
| Lead | 3.043 | 1.413 |
| Zinc | 11.090 | 4.565 |
| Aluminum | 66.410 | 29.450 |
| Ammonia (as N) | 1,449.000 | 636.900 |
(d) Subpart C - Demagging Wet Air Pollution Control.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (lb/million lbs) of aluminum demagged | ||
| Lead | 0.216 | 0.100 |
| Zinc | 0.786 | 0.324 |
| Aluminum | 4.711 | 2.090 |
| Ammonia (as N) | 102.800 | 45.180 |
(e) Subpart C - Delacquering Wet Air Pollution Control.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| 1 At the source. | ||
| mg/kg (pound's per million pounds) of aluminum delacquered | ||
| Lead | 0.093 | 0.043 |
| Zinc | 0.340 | 0.140 |
| Aluminum | 2.035 | 0.903 |
| Ammonia (as N) | 44.389 | 19.514 |
| Total phenolics (4-AAP method) 1 | 0.004 | |
(f) Subpart C - Direct Chill Casting Contact Cooling.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum cast | ||
| Lead | .372 | .173 |
| Zinc | 1.356 | .558 |
| Aluminum | 8.120 | 3.602 |
| Ammonia (as N) | 177.200 | 77.880 |
(g) Subpart C - Ingot Conveyor Casting Contact Cooling (When Chlorine Demagging Wet Air Pollution Control is Not Practiced On-Site).
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (lb/million lbs) of aluminum cast | ||
| Lead | 0.019 | 0.009 |
| Zinc | 0.068 | 0.028 |
| Aluminum | 0.409 | 0.182 |
| Ammonia (as N) | 8.931 | 3.926 |
(h) Subpart C - Ingot Conveyor Casting Contact Cooling (When Chloride Demagging Wet Air Pollution Control is Practiced On Site).
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum cast | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Aluminum | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
(i) Subpart C - Stationary Casting Contact Cooling.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum cast | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Aluminum | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
(j) Subpart C - Shot Casting Contact Cooling.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum cast | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Aluminum | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
[49 FR 8796, Mar. 8, 1984; 49 FR 26739, June 29, 1984, as amended at 49 FR 29794, July 24, 1984; 52 FR 25559, July 7, 1987]
§421.34 Standards of performance for new sources.
Any new source subject to this subpart shall achieve the following new source performance standards:
(a) Subpart C - Scrap Drying Wet Air Pollution Control.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average. |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum scrap dried | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Aluminum | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
| Total suspended solids | .000 | .000 |
| Oil and grease | .000 | .000 |
| pH | ( 1) | ( 1) |
| 1 Within the range of 7.0 to 10.0 at all times | ||
(b) Subpart C - Scrap Screening and Milling.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum scrap screened and milled | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Aluminum | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
| Total suspended solids | .000 | .000 |
| Oil and grease | .000 | .000 |
| pH | ( 1) | ( 1) |
| 1 Within the range of 7.0 to 10.0 at all times. | ||
(c) Subpart C - Dross Washing.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of dross washed | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Aluminum | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
| Total suspended solids | .000 | .000 |
| Oil and grease | .000 | .000 |
| pH | ( 1) | ( 1) |
| 1 Within the range of 7.0 to 10.0 at all times. | ||
(d) Subpart C - Demagging Wet Air Pollution Control.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (lb/million lbs) of aluminum demagged | ||
| Lead | 0.216 | 0.100 |
| Zinc | 0.786 | 0.324 |
| Aluminum | 4.711 | 2.090 |
| Ammonia (as N) | 102.800 | 45.180 |
| Total suspended solids | 11.570 | 9.252 |
| Oil and grease | 7.710 | 7.710 |
| pH | ( 1) | ( 1) |
| 1 Within the range of 7.0 to 10.0 at all times. | ||
(e) Subpart C - Delacquering Wet Air Pollution Control.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum delacquered | ||
| Lead | 0.093 | 0.043 |
| Zinc | 0.340 | 0.140 |
| Aluminum | 2.035 | 0.903 |
| Ammonia (as N) | 44.389 | 19.514 |
| Total phenolics (4-AAP method) 1 | 0.004 | |
| Total suspended solids | 4.995 | 3.996 |
| Oil and grease | 3.330 | 3.330 |
| pH | ( 2) | ( 2) |
| 1 At the source. 2 Within the range of 7.0 to 10.0 at all times. | ||
(f) Subpart C - Direct Chill Casting Contact Cooling.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum cast | ||
| Lead | .372 | .173 |
| Zinc | 1.356 | .558 |
| Aluminum | 8.120 | 3.602 |
| Ammonia (as N) | 177.200 | 77.880 |
| Total suspended solids | 19.940 | 15.950 |
| Oil and grease | 13.290 | 13.290 |
| pH | ( 1) | ( 1) |
| 1 Within the range of 7.0 to 10.0 at all times. | ||
(g) Subpart C - Ingot Conveyor Casting Contact Cooling (When Chlorine Demagging Wet Air Pollution Control is Not Practiced On-Site).
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (lb/million lbs) of aluminum cast | ||
| Lead | 0.019 | 0.009 |
| Zinc | 0.068 | 0.028 |
| Aluminum | 0.409 | 0.182 |
| Ammonia (as N) | 8.931 | 3.926 |
| Total suspended solids | 1.005 | 0.804 |
| Oil and grease | 0.670 | 0.670 |
| pH | ( 1) | ( 1) |
| 1 Within the range of 7.0 to 10.0 at all times. | ||
(h) Subpart C - Ingot Conveyor Casting Contact Cooling (When Chlorine Demagging Wet Air Pollution Control is Practiced On Site).
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum cast | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Aluminum | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
| Total suspended solids | .000 | .000 |
| Oil and grease | .000 | .000 |
| pH | ( 1) | ( 1) |
| 1Within the range of 7.0 to 10.0 at all times. | ||
(i) Subpart C - Stationary Casting Contact Cooling.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum cast | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Aluminum | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
| Total suspended solids | .000 | .000 |
| Oil and grease | .000 | .000 |
| pH | ( 1) | ( 1) |
| 1Within the range of 7.0 to 10.0 at all times. | ||
(j) Subpart C - Shot Casting Contact Cooling.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum cast | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Aluminum | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
| Total suspended solids | .000 | .000 |
| Oil and grease | .000 | .000 |
| pH | ( 1) | ( 1) |
| 1 Within the range of 7.0 to 10.0 at all times. | ||
[49 FR 8796, Mar. 8, 1984, as amended at 49 FR 29794, July 24, 1984; 52 FR 25559, July 7, 1987]
§421.35 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 secondary aluminum process wastewater introduced into a POTW shall not exceed the following values:
(a) Subpart C - Scrap Drying Wet Air Pollution Control.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum scrap dried | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
(b) Subpart C - Scrap Screening and Milling.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum scrap screened and milled | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
(c) Subpart C - Dross Washing.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of dross washed | ||
| Lead | 3.043 | 1.413 |
| Zinc | 11.090 | 4.565 |
| Ammonia (as N) | 1,449.000 | 636.000 |
(d) Subpart C - Demagging Wet Air Pollution Control.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (lb/million lbs) of aluminum demagged | ||
| Lead | 0.216 | 0.100 |
| Zinc | 0.786 | 0.324 |
| Amomonia (as N) | 102.800 | 45.180 |
(e) Subpart C - Delacquering Wet Air Pollution Control.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| 1 At the source. | ||
| mg/kg (pounds per million pounds) of aluminum delacquered | ||
| Lead | 0.093 | 0.043 |
| Zinc | 0.340 | 0.140 |
| Ammonia (as N) | 44.389 | 19.514 |
| Total phenolics (4-AAP) method) 1 | 0.004 | |
(f) Subpart C - Direct Chill Casting Contact Cooling.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum cast | ||
| Lead | .372 | .173 |
| Zinc | 1.356 | .558 |
| Ammonia (as N) | 177.200 | 77.800 |
(g) Subpart C - Ingot Conveyor Casting Contact Cooling (When Chlorine Demagging Wet Air Pollution Control is Not Practiced On-Site).
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (lb/million lbs) of aluminum cast | ||
| Lead | 0.019 | 0.009 |
| Zinc | 0.068 | 0.028 |
| Amomonia (as N) | 8.931 | 3.926 |
(h) Subpart C - Ingot Conveyor Casting Contact Cooling. (When Chlorine Demagging Wet Air Pollution Control is Practiced On Site.)
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum cast | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
(i) Subpart C - Stationary Casting Contact Cooling.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum cast | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
(j) Subpart C - Shot Casting Contact Cooling.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum cast | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
[49 FR 8796, Mar. 8, 1984, as amended at 49 FR 29794, July 24, 1984; 52 FR 25560, July 7, 1987]
§421.36 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 introduced in secondary aluminum process wastewater into a POTW shall not exceed the following values:
(a) Subpart C - Scrap Drying Wet Air Pollution Control.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum scrap dried | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
(b) Subpart C - Scrap Screening and Milling.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum scrap screened and milled | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
(c) Subpart C - Dross Washing.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of dross washed | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
(d) Subpart C - Demagging Wet Air Pollution Control.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (lb/million lbs) of aluminum demagged | ||
| Lead | 0.216 | 0.100 |
| Zinc | 0.786 | 0.324 |
| Amomonia (as N) | 102.800 | 45.180 |
(e) Subpart C - Delacquering Wet Air Pollution Control
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| 1 At the source. | ||
| mg/kg (pounds per million pounds) of aluminum delacquered | ||
| Lead | 0.093 | 0.043 |
| Zinc | 0.340 | 0.140 |
| Ammonia (as N) | 44.389 | 19.514 |
| Total phenolics (4-AAP method) 1 | 0.004 | |
(f) Subpart C - Direct Chill Casting Contact Cooling.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum cast | ||
| Lead | .372 | .173 |
| Zinc | 1.356 | .558 |
| Ammonia (as N) | 177.200 | 77.880 |
(g) Subpart C - Ingot Conveyor Casting Control Cooling (When Chlorine Demagging Wet Air Pollution Control is Not Practiced On-Site).
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (lb/million lbs) of aluminum cast | ||
| Lead | 0.019 | 0.009 |
| Zinc | 0.068 | 0.028 |
| Amomonia (as N) | 8.931 | 3.926 |
(h) Subpart C - Ingot Conveyor Casting Contact Cooling (When Chlorine Demagging Wet Air Pollution Control Is Practiced on Site).
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum cast | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
(i) Subpart C - Stationary Casting Contact Cooling.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum cast | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
(j) Subpart C - Shot Casting Contact Cooling.
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
|---|---|---|
| mg/kg (pounds per million pounds) of aluminum cast | ||
| Lead | .000 | .000 |
| Zinc | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
[49 FR 8796, Mar. 8, 1984, as amended at 49 FR 29794, July 24, 1984; 52 FR 25560, July 7, 1987]
§421.37 [Reserved]
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Copyright 2025 J. J. Keller & Associate, Inc. For re-use options please contact copyright@jjkeller.com or call 800-558-5011.