Textile Dyeing Wastewater Treatment: Complete Chemical Solution

Textile Wastewater Challenges

Parameter	Typical Range	Discharge Limit
Color	200–2000 Pt-Co	< 40–80
COD	500–3000 mg/L	< 80–150
BOD	100–600 mg/L	< 20–30
pH	8–12	6–9
TSS	200–1000 mg/L	< 30–50

Treatment Train

Stage 1: pH Adjustment + Coagulation

• Adjust pH to 7–8 with HCl or H₂SO₄
• Add PAC 100–200 ppm or PFS 80–150 ppm
• PFS preferred for better color removal
• Add anionic PAM 1–3 ppm for floc settling

Stage 2: Biological Treatment

• Anaerobic-aerobic (A/O) process for BOD and partial color removal
• HRT: 8–12 hours aerobic, 4–6 hours anaerobic
• Achieves 60–80% COD removal, 40–60% color removal

Stage 3: Advanced Oxidation (if needed)

Fenton Oxidation for persistent color and COD:

1. Adjust pH to 3.0–3.5
2. Add FeSO₄: 200–500 ppm
3. Add H₂O₂ (50%): 300–800 ppm
4. Stir 60–120 minutes
5. Raise pH to 8–9 → iron hydroxide precipitates with oxidized dye
6. Settle + filter

Typical Fenton performance: 80–95% color removal, 50–70% additional COD removal.

Stage 4: Decolorization Polishing

• Decolorant (quaternary ammonium or dicyandiamide type): 50–200 ppm
• For reactive dyes: dicyandiamide type > 95% decolorization
• For mixed/disperse dyes: quaternary ammonium type preferred

Stage 5: Sludge Dewatering

• Chemical sludge from coagulation + Fenton: condition with CPAM (high charge)
• Biological sludge: condition with CPAM (medium charge)
• Filter press or centrifuge dewatering