Section 421.32 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best practicable control technology currently availableExcept 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 practicable technology currently available:
(a) The following limitations establish the quantity or quality of pollutants or pollutant properties, which may be discharged by a point source subject to the provisions of this subpart and which uses water for metal cooling, after application of the best practicable control technology currently available: There shall be no discharge of process wastewater pollutants to navigable waters.(b) The following limitations establish the quantity or quality of pollutants or pollutant properties which may be discharged by a point source subject to the provisions of this subpart and which uses aluminum fluoride in its magnesium removal process ("demagging process"), after application of the best practicable control technology currently available: There shall be no discharge of process wastewater pollutants to navigable waters.(c) The following limitations establish the quantity or quality of pollutants or pollutant properties controlled by this section, which may be discharged by a point source subject to the provisions of this subpart and which uses chlorine in its magnesium removal process, after application of the best practicable control technology currently available: Effluent Limitations
| Effluent characteristic | Average of daily values for 30 consecutive days shall not exceed- |
| Metric units (kilograms per 1,000 kg magnesium removed) |
| TSS | 175 |
| COD | 6.5 |
| pH | (1) |
1 Within the range of 7.5 to 9.0.
(d) The following limitations establish the quantity or quality of pollutants or pollutant properties which may be discharged by a point source subject to the provisions of this subpart and which processes residues by wet methods, after application of the best practical control technology currently available: Effluent Limitations
| Effluent characteristic | Average of daily values for 30 consecutive days shall not exceed- |
| Metric units (kilograms per 1,000 kg of product) |
| TSS | 1.5 |
| Fluoride | 0.4 |
| Ammonia (as N) | 0.01 |
| Aluminum | 1.0 |
| Copper | 0.003 |
| COD | 1.0 |
| pH | (1) |
1 Within the range of 7.5 to 9.0.