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Federal regulations · Through 2026-08-25 · Newer source version available

40 CFR 421.256: Pretreatment standards for new sources.

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Where this section sits in the code
  1. Title 40—Protection of Environment
  2. CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY
  3. SUBCHAPTER N—EFFLUENT GUIDELINES AND STANDARDS
  4. PART 421—NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY
  5. Subpart W—Primary Precious Metals and Mercury Subcategory

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 in primary precious metals and mercury process wastewater introduced into a POTW shall not exceed the following values:

(a) Smelter wet air pollution control.

PSNS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average

mg/troy ounce of gold and silver smelted

Lead 0.364 0.169

Mercury 0.195 0.078

Silver 0.377 0.156

Zinc 1.326 0.546

Gold 0.130

(b) Silver chloride reduction spent solution.

PSNS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average

mg/troy ounce of silver reduced in solution

Lead 0.112 0.052

Mercury 0.060 0.024

Silver 0.116 0.048

Zinc 0.408 0.168

Gold 0.040

(c) Electrolytic cells wet air pollution control.

PSNS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average

mg/troy ounce of gold refined electrolytically

Lead 5.544 2.574

Mercury 2.970 1.188

Silver 5.742 2.376

Zinc 20.200 8.316

Gold 1.980

(d) Electrolyte preparation wet air pollution control.

PSNS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average

mg/troy ounce of silver in electrolyte produced

Lead 0.014 0.007

Mercury 0.008 0.003

Silver 0.015 0.006

Zinc 0.051 0.021

Gold 0.005

(e) Calciner wet air pollution control.

PSNS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average

mg/kg (pounds per million pounds) of mercury condensed

Lead 6.160 2.860

Mercury 3.300 1.320

Silver 6.380 2.640

Zinc 22.440 9.240

Gold 2.200

(f) Calcine quench water.

PSNS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average

mg/kg (pounds per million pounds) of mercury condensed

Lead 4.928 2.288

Mercury 2.640 1.056

Silver 5.104 2.112

Zinc 17.950 7.392

Gold 1.760

(g) Calciner stack gas contact cooling water.

PSNS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average

mg/kg (pounds per million pounds) of mercury condensed

Lead 1.162 0.540

Mercury 0.623 0.249

Silver 1.204 0.498

Zinc 4.233 1,743

Gold 0.415

(h) Condenser blowdown.

PSNS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average

mg/kg (pounds per million pounds) of mercury condensed

Lead 3.864 1.794

Mercury 2.070 0.828

Silver 4.002 1.656

Zinc 14.080 5.656

Gold 1.380

(i) Mercury cleaning bath water.

PSNS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average

mg/kg (pounds per million pounds) of mercury condensed

Lead 0.392 0.182

Mercury 0.210 0.084

Silver 0.406 0.168

Zinc 1.428 0.588

Gold 0.140

Collected 2026-08-27T02:26:04Z. Source file · JSON

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