CFR > Title 40 - Protection of Environment > CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY > SUBCHAPTER N—EFFLUENT GUIDELINES AND STANDARDS (Parts 400–471) > PART 471—NONFERROUS METALS FORMING AND METAL POWDERS POINT SOURCE CATEGORY > SUBPART B—Magnesium Forming Subcategory (§471.20 to §471.26) > 471.21—Effluent limitations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available (BPT).

471.21—Effluent limitations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available (BPT).

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 for the process operations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available (BPT):
(a) Rolling spent emulsions.
Subpart B—BPT
Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/off-kg (pounds per million off-pounds) of magnesium rolled with emulsions
Chromiun 0.033 0.014
Zinc 0.109 0.046
Ammonia 9.95 4.37
Fluoride 4.440 1.97
Oil and grease 1.49 0.895
TSS 3.06 1.46
pH (1)
1 Within the range of 7.5 to 10.0 at all times.
(b) Forging spent lubricants—Subpart B—BPT. There shall be no discharge of process wastewater pollutants.
(c) Forging contact cooling water.
Subpart B—BPT
Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/off-kg (pounds per million off-pounds) of forged magnesium cooled with water
Chromium 1.27 0.520
Zinc 4.22 1.77
Ammonia 385 170
Fluoride 172 76.3
Oil and grease 57.8 34.7
TSS 119 56.4
pH (1)
1 Within the range of 7.5 to 10.0 at all times.
(d) Forging equipment cleaning wastewater.
Subpart B—BPT
Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/off-kg (pounds per million off-pounds) of magnesium forged
Chromium 0.018 0.007
Zinc 0.059 0.025
Ammonia 5.32 2.34
Fluoride 2.38 1.06
Oil and grease 0.798 0.479
TSS 1.64 0.778
pH (1)
1 Within the range of 7.5 to 10.0 at all times.
(e) Direct chill casting contact cooling water.
Subpart B—BPT
Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/off-kg (pounds per million off-pounds) of magnesium cast with direct chill methods
Chromium 1.74 0.711
Zinc 5.77 2.41
Ammonia 527 232
Fluoride 235 105
Oil and grease 79.0 47.4
TSS 162 77.1
pH (1)
1 Within the range of 7.5 to 10.0 at all times.
(f) Surface treatment spent baths.
Subpart B—BPT
Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/off-kg (pounds per million off-pounds) of magnesium surface treated
Chromium 0.205 0.084
Zinc 0.681 0.285
Ammonia 62.1 27.3
Fluoride 27.8 12.3
Oil and grease 9.32 5.59
TSS 19.1 9.09
pH (1)
1 Within the range of 7.5 to 10.0 at all times.
(g) Surface treatment rinse.
Subpart B—BPT
Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/off-kg (pounds per million off-pounds) of magnesium surface treated
Chromium 8.32 3.4
Zinc 27.6 11.5
Ammonia 2520 1110
Fluoride 1130 499
Oil and grease 378 227
TSS 775 369
pH (1)
1 Within the range of 7.5 to 10.0 at all times.
(h) Sawing or grinding spent emulsions.
Subpart B—BPT
Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/off-kg (pounds per million off-pounds) of magnesium sawed or ground
Chromium 0.009 0.004
Zinc 0.029 0.012
Ammonia 2.60 1.15
Fluoride 1.16 0.515
Oil and grease 0.390 0.234
TSS 0.800 0.381
pH (1)
1 Within the range of 7.5 to 10.0 at all times.
(i) Degreasing spent solvents—Subpart B—BPT. There shall be no discharge of process wastewater pollutants.
(j) Wet air pollution control scrubber blowdown.
Subpart B—BPT
Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/off-kg (pounds per million off-pounds) of magnesium sanded and repaired or forged
Chromium 0.273 0.112
Zinc 0.904 0.378
Ammonia 82.5 36.3
Fluoride 36.9 16.4
Oil and grease 12.4 7.43
TSS 25.4 12.1
pH (1)
1 Within the range of 7.5 to 10.0 at all times.
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 for the process operations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available (BPT):
(a) Rolling spent emulsions.
Subpart B—BPT
Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/off-kg (pounds per million off-pounds) of magnesium rolled with emulsions
Chromiun 0.033 0.014
Zinc 0.109 0.046
Ammonia 9.95 4.37
Fluoride 4.440 1.97
Oil and grease 1.49 0.895
TSS 3.06 1.46
pH (1)
1 Within the range of 7.5 to 10.0 at all times.
(b) Forging spent lubricants—subpart B—BPT. There shall be no discharge of process wastewater pollutants.
(c) Forging contact cooling water.
Subpart B—BPT
Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/off-kg (pounds per million off-pounds) of forged magnesium cooled with water
Chromium 1.27 0.520
Zinc 4.22 1.77
Ammonia 385 170
Fluoride 172 76.3
Oil and grease 57.8 34.7
TSS 119 56.4
pH (1)
1 Within the range of 7.5 to 10.0 at all times.
(d) Forging equipment cleaning wastewater.
Subpart B—BPT
Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/off-kg (pounds per million off-pounds) of magnesium forged
Chromium 0.018 0.007
Zinc 0.059 0.025
Ammonia 5.32 2.34
Fluoride 2.38 1.06
Oil and grease 0.798 0.479
TSS 1.64 0.778
pH (1)
1 Within the range of 7.5 to 10.0 at all times.
(e) Direct chill casting contact cooling water.
Subpart B—BPT
Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/off-kg (pounds per million off-pounds) of magnesium cast with direct chill methods
Chromium 1.74 0.711
Zinc 5.77 2.41
Ammonia 527 232
Fluoride 235 105
Oil and grease 79.0 47.4
TSS 162 77.1
pH (1)
1 Within the range of 7.5 to 10.0 at all times.
(f) Surface treatment spent baths.
Subpart B—BPT
Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/off-kg (pounds per million off-pounds) of magnesium surface treated
Chromium 0.205 0.084
Zinc 0.681 0.285
Ammonia 62.1 27.3
Fluoride 27.8 12.3
Oil and grease 9.32 5.59
TSS 19.1 9.09
pH (1)
1 Within the range of 7.5 to 10.0 at all times.
(g) Surface treatment rinse.
Subpart B—BPT
Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/off-kg (pounds per million off-pounds) of magnesium surface treated
Chromium 8.32 3.4
Zinc 27.6 11.5
Ammonia 2520 1110
Fluoride 1130 499
Oil and grease 378 227
TSS 775 369
pH (1)
1 Within the range of 7.5 to 10.0 at all times.
(h) Sawing or grinding spent emulsions.
Subpart B—BPT
Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/off-kg (pounds per million off-pounds) of magnesium sawed or ground
Chromium 0.009 0.004
Zinc 0.029 0.012
Ammonia 2.60 1.15
Fluoride 1.16 0.515
Oil and grease 0.390 0.234
TSS 0.800 0.381
pH (1)
1 Within the range of 7.5 to 10.0 at all times.
(i) Degreasing spent solvents—subpart B—BPT. There shall be no discharge of process wastewater pollutants.
(j) Wet air pollution control scrubber blowdown.
Subpart B—BPT
Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/off-kg (pounds per million off-pounds) of magnesium sanded and repaired or forged
Chromium 0.273 0.112
Zinc 0.904 0.378
Ammonia 82.5 36.3
Fluoride 36.9 16.4
Oil and grease 12.4 7.43
TSS 25.4 12.1
pH (1)
1 Within the range of 7.5 to 10.0 at all times.