🌍 Total Dissolved Solids in Tannery Effluent: Tackling Environmental Challenges & Exploring Solutions

The leather industry faces a critical environmental hurdle—Total Dissolved Solids (TDS) in tannery effluent. High TDS concentrations, largely from salts used in preservation and various process chemicals, contribute significantly to wastewater pollution. Regulatory limits for TDS vary worldwide, with stringent standards set in places like South Africa, Italy, and India. Yet, compliance remains a persistent challenge due to traditional tanning methods.

🧪 What Contributes to High TDS?

1️⃣ Preservation: Raw hides and skins are often preserved with up to 50% salt by weight.
2️⃣ Process Chemicals: Ammonium salts in deliming, chrome salts in tanning, and electrolytes in dyeing all add to TDS levels.
3️⃣ Treatment Limitations: Standard wastewater treatments are effective for suspended solids but struggle with dissolved salts.
4️⃣ Preservation Alternatives: While some regions use short-term chemical preservation or chilling, long-term alternatives to salting are still underdeveloped.

🌱 How Can We Reduce TDS Impact?

3.1 Source Reduction

• 🚿 Remove salt mechanically or manually before soaking.
• ✂️ Optimise trimming and prefleshing to reduce salt use.
• 🍋 Explore organic acids or CO₂ in deliming instead of ammonium salts.
• 🌿 Use short floats to cut down chemical loads.

3.2 Recycling and Process Efficiency

• 🔄 Recycle pickling and tanning floats to reuse salt-heavy liquors.
• 🏗️ Recover chrome from tanning effluent, reducing sulfate discharge.
• 🎨 Minimise solid additives by using liquid dyes and syntans.

3.3 Advanced Treatment Technologies

• 🌞 Evaporation: Natural evaporation lagoons are used in some areas, but advanced methods like spray-assisted evaporation are making these systems more efficient.
• 💧 Reverse Osmosis (RO): RO systems can recover up to 80% of process water, reducing TDS from 15,000 mg/L to below 500 mg/L, though disposal of concentrated brine remains a challenge.
• 🔬 Emerging Technologies: Research is ongoing into affordable and effective methods for separating high-salinity waste.

🔮 What Does the Future Hold for Tannery Effluent Management?

With tighter regulations and a focus on sustainability, tanneries must embrace innovative approaches to reduce their environmental footprint:

✅ Salt Reduction: Strategies for cutting TDS at the source.
✅ Circular Economy: Efficient recycling and reuse of process water and chemicals.
✅ Advanced Treatment: Investment in cutting-edge technologies that ensure long-term sustainability.

Adopting these strategies not only helps tanneries comply with regulations but also boosts efficiency and resource conservation, paving the way for a more sustainable leather industry. 🌎💡