The Ministry of Environment, Forest, and Climate Change on March 26th 2025 has officially notified the Environment (Protection) Second Amendment Rules, 2025, bringing forth critical updates aimed at strengthening environmental safeguards.
Key Highlights of the Amendment:
1. Stricter Effluent Standards for Caustic Soda Plants
The new rules impose tighter limits on wastewater discharge to inland water bodies and land for irrigation. Here’s what’s new:
| Parameter | Standard (mg/l) | Key Notes |
| Bioassay Test | 90% fish survival (96 hours) | Conducted as per IS: 6582-1971 standards |
| pH Range | 6.5 – 8.5 | Standard for effluent pH |
| Chloride | 250 | Applies after 2 years for older plants |
| Total Suspended Solids | 100 | |
| Total Dissolved Solids | 2100 (#) | Max 3100 mg/l in treated effluent; Na+ absorption ratio ≤ 26 |
| Oil & Grease | 5 | |
| Residual Free Chlorine | 0.5 | |
| Sulphate | 200 | Applies after 2 years for older plants |
| Water Consumption | 5 m³/ton of caustic soda production | Excludes cooling tower blowdown |
Note: These standards apply to standalone caustic soda plants using membrane cell technology, including those producing hydrochloric acid, hydrogen, chlorine, and hypo.
2. Fugitive Emission Standards (For Cell House & Near HCl Tower)
| Parameter | Standard (µg/m³) | Compliance Timeline |
| Chlorine | 7 | Adhere to Factories Act, 1948 for 2 years |
| Hydrochloric Acid | 10 | Stricter standards apply after 2 years |
After 2 years, industry-specific fugitive emission standards will take precedence.
3. Process Emission Standards (For Hypo & HCl Stacks)
| Location | Parameter | Standard (mg/Nm³) | Notes |
| Hypo Stack | Chlorine | 5 | |
| HCl Stack | Chlorine | 5 | |
| Hydrochloric Acid | 10 (initial) / 5 (after 2 years) | Stricter limits after 2 years |
4. Wastewater Generation & Load-Based Standards
| Industry | Quantum Limit (Kg/tonne) | Standards |
| Caustic Soda | Chloride: 0.25 | For standalone membrane cell plants |
| Total Suspended Solids: 0.1 | Applies to inland water discharge only | |
| Total Dissolved Solids: 2.1 | Not applicable for deep-sea disposal | |
| Oil & Grease: 0.005 | ||
| Residual Free Chlorine: 0.0005 | ||
| Sulphate: 0.2 | Applies after 2 years for old plants |
Wastewater Limit: 1 m³ per ton of caustic soda production (Cooling tower blowdown is excluded).
What’s Changing & Why?
- Stronger Environmental Protection: Tougher limits on pollutants to protect water bodies.
- Focus on Sustainability: Encouraging cleaner production technologies.
- Regulatory Compliance: Industries must comply within phased timelines, especially for older plants.
Compliance Timeline:
- 2 Years: For older caustic soda plants to meet new chloride, sulphate, and emission standards.
- 1 Year: Full implementation of updated rules post-publication.
Why This Matters:
This landmark amendment reflects India’s growing commitment to environmental sustainability, ensuring industries contribute to a cleaner, healthier future.
Effective Date : 26 March 2026
