40 CFR 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.