{"data":{"id":"us/40-cfr-421.23","jurisdiction":"us","citation":"40 CFR 421.23","heading":"Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best available technology economically achievable.","body":"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:\n(a) Subpart B—Anode and Cathode Paste Plant Wet Air Pollution Control\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pounds per million pounds) of paste produced\nBenzo(a)pyrene 0.005 0.002\nAntimony .263 .117\nNickel .075 .050\nAluminum .831 .369\nFluoride 8.092 3.591\n(b) Subpart (B)—Anode Contact Cooling and Briquette Quenching.\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pounds per million pounds) of anodes cast\nBenzo(a)pyrene 0.007 0.003\nAntimony .403 .180\nNickel .115 .077\nAluminum 1.277 .566\nFluoride 12.440 5.518\n(c) Subpart (B)—Anode Bake Plant Wet Air Pollution Control (Closed Top Ring Furnace).\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pounds per million pounds) of anodes baked\nBenzo(a)pyrene 0.146 0.067\nAntimony 8.346 3.719\nNickel 2.378 1.600\nAluminum 26.420 11.720\nFluoride 257.300 114.200\n(d) Subpart B—Anode Bake Plant Wet Air Pollution Control (Open Top Ring Furnace With Spray Tower Only).\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pounds per million pounds) of anodes baked\nBenzo(a)pyrene 0.002 0.001\nAntimony .097 .043\nNickel .028 .019\nAluminum .306 .136\nFluoride 2.975 1.320\n(e) Subpart B—Anode Bake Plant Wet Air Pollution Control (Open Top Ring Furnace With Wet Electrostatic Precipitator and Spray Tower).\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pounds per million pounds) of anodes baked\nBenzo(a)pyrene 0.025 0.011\nAntimony 1.409 .628\nNickel .402 .270\nAluminum 4.461 1.979\nFluoride 43.440 19.270\n(f) Subpart B—Anode Bake Plant Wet Air Pollution Control (Tunnel Kiln).\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pounds per million pounds) of anodes baked\nBenzo(a)pyrene 0.038 0.018\nAntimony 2.197 .979\nNickel .626 .421\nAluminum 6.953 3.084\nFluoride 67.710 30.050\n(g) Subpart B—Cathode Reprocessing (Operated With Dry Potline Scrubbing and Not Commingled With Other Process or Nonprocess Waters).\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pounds per million pounds) of cryolite recovered\nBenzo(a)pyrene 1.181 0.547\nAntimony 420.400 189.200\nCyanide 157.600 70.060\nNickel 80.570 35.030\nAluminum 273.200 122.600\nFluoride 29,430.000 13,310.000\n(h) Subpart B—Cathode Reprocessing (Operated With Dry Potline Scrubbing and Commingled With Other Process or Nonprocess Waters).\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pounds per million pounds) of cryolite recovered\nBenzo(a)pyrene 1.181 0.547\nAntimony 67.610 30.120\nCyanide 157.600 70.060\nNickel 19.270 12.960\nAluminum 214.000 94.930\nFluoride 2,084.000 924.800\n(i) Subpart B—Cathode Reprocessing (Operated With Wet Potline Scrubbing).\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pound per million pounds) of cryolite recovered\nBenzo(a)pyrene .000\nAntimony .000 .000\nCyanide .000 .000\nNickel .000 .000\nAluminum .000 .000\nFluoride .000 .000\n(j) Subpart B—Potline Wet Air Pollution Control (Operated Without Cathode Reprocessing).\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pound per million pounds) of aluminum produced from electrolytic reduction\nBenzo(a)pyrene 0.028 0.013\nAntimony 1.618 .721\nNickel .461 .310\nAluminum 5.120 2.271\nFluoride 49.860 22.130\n(k) Subpart B—Potline Wet Air Pollution Control (Operated With Cathode Reprocessing and Not Commingled With Other Process or Nonprocess Waters).\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pound per million pounds) of aluminum produced from electrolytic reduction\nBenzo(a)pyrene 0.028 0.013\nAntimony 10.060 4.525\nCyanide 3.771 1.676\nNickel 1.928 .838\nAluminum 6.537 2.933\nFluoride 703.900 318.500\n(l) Potline Wet Air Pollution Control Cooperated With Cathode Reprocessing and Commingled With Other Process or Nonprocess Wastewaters).\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pound per million pounds) of aluminum produced from electrolytic reduction\nBenzo(a)pyrene 0.028 0.013\nAntimony 1.618 .721\nCyanide 3.771 1.676\nNickel 0.461 .310\nAluminum 5.120 2.271\nFluoride 49.860 22.130\n(m) Subpart B—Potroom Wet Air Pollution Control.\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pound per million pounds) of aluminum produced from electrolytic reduction\nBenzo(a)pyrene 0.056 0.026\nAntimony 3.204 1.428\nNickel .913 .614\nAluminum 10.140 4.499\nFluoride 98.770 43.830\n(n) Subpart B—Potline SO2 Emissions Wet Air Pollution Control.\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pound per million pounds) of aluminum produced from electrolytic reduction\nBenzo(a)pyrene 0.045 0.021\nAntimony 2.588 1.153\nNickel .738 .496\nAluminum 8.194 3.634\nFluoride 79.790 35.400\n(o) Subpart B—Degassing Wet Air Pollution Control.\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pound per million pounds) of aluminum produced from electrolytic reduction\nBenzo(a)pyrene (1) (1)\nAntimony 5.036 2.244\nNickel 1.435 .965\nAluminum 15.940 7.071\nFluoride 155.300 68.880\n1 There shall be no discharge allowance for this pollutant.\n(p) Subpart B—Pot Repair and Pot Soaking.\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pound per million pounds) of aluminum produced from electrolytic reduction\nBenzo(a)pyrene .000\nAntimony .000 .000\nNickel .000 .000\nAluminum .000 .000\nFluoride .000 .000\n(q) Subpart B—Direct Chill Casting Contact Cooling.\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pound per million pounds) of aluminum product from direct chill casting\nBenzo(a)pyrene (1) (1)\nAntimony 2.565 1.143\nNickel .731 .492\nAluminum 8.120 3.602\nFluoride 79.080 35.090\n1 There shall be no discharge allowance for this pollutant.\n(r) Subpart B—Continuous Rod Casting Contact Cooling.\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pound per million pounds) of aluminum product from rod casting\nBenzo(a)pyrene (1) (1)\nAntimony .201 .089\nNickel .057 .038\nAluminum .636 .282\nFluoride 6.188 2.746\n1 There shall be no discharge allowance for this pollutant.\n(s) Subpart B—Stationary Casting or Shot Casting Contact Cooling.\nBAT Effluent Limitations\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/kg (pound per million pounds) of aluminum product from stationary casting or shot casting\nBenzo(a)pyrene .000\nAntimony .000 .000\nNickel .000 .000\nAluminum .000 .000\nFluoride .000 .000","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER N—EFFLUENT GUIDELINES AND STANDARDS","PART 421—NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY","Subpart B—Primary Aluminum Smelting Subcategory"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-40.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:04Z","sha256":"3ff1f1808b336da3ec207490bbab616f42d04e5a1a516ac76a0c6978cb860fe2","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-421.22","next":"us/40-cfr-421.24"},"notice":"GroundRules: Original legal text. Not legal advice."}