Effluent limitations representing the degree of effluent reduction attainable by the application of the best available technology economically achievable (BAT).

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 available technology economically achievable (BAT): (a) Rolling spent emulsions. Subpart B—BAT 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 Chromium 0.033 0.014 Zinc 0.109 0.046 Ammonia 9.95 4.37 Fluoride 4.44 1.97 (b) Forging spent lubricants—subpart B—BAT. There shall be no discharge of process wastewater pollutants. (c) Forging contact cooling water. Subpart B—BAT 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 0.127 0.052 Zinc 0.422 0.177 Ammonia 38.5 17.0 Fluoride 17.2 7.63 (d) Forging equipment cleaning wastewater. Subpart B—BAT 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 0.002 0.0007 Zinc 0.006 0.003 Ammonia 0.532 0.234 Fluoride 0.238 0.106 (e) Direct chill casting contact cooling water. Subpart B—BAT 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 (f) Surface treatment spent baths. Subpart B—BAT 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 (g) Surface treatment rinse. Subpart B—BAT 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 0.832 0.340 Zinc 2.76 1.16 Ammonia 252 111 Fluoride 113 49.9 (h) Sawing or grinding spent emulsions. Subpart B—BAT 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 (i) Degreasing spent solvents—subpart B—BAT. There shall be no discharge of process wastewater pollutants. (j) Wet air pollution control scrubber blowdown. Subpart B—BAT 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