Textiles have one of the largest water footprints. Dyeing is a big problem both in terms of water use and pollution. It’s not realistic to stop dyeing and eliminate mass-market products such as cotton and polyester. The Industry’s challenge, therefore, is to adopt more water-friendly technologies and to effectively treat the water it uses.
While Industry is continuously trying to adopt modern processes to reduce water consumption, we at EROS, are helping them to treat the polluted water generated by them and therefore minimizing the impact of water use.
Eros Envirotech (P) Ltd., is a Ludhiana (India) based environmental engineering company engaged in providing turnkey solutions for pollution control to the industry in textile/ yarn dyeing and other fields for over a decade now.
We provide comprehensive and reliable solutions to the industry within cost and time parameters. Further, our design and project execution skills help us to engage clients meaningfully to understand their requirements and deliver on them.
Steps involving discharge of water in different dyeing processes
Polyester Cotton
Typical Waste Water Treatment Process
Waste Water Treatment in Textile Dyeing is a multi-stage process. They can be broadly classified as:
- Preliminary & Primary Treatment: Physico-Chemical treatment leading to reduction of TSS and some extent BOD/COD
- Secondary Treatment: Biological treatment leading to reduction of BOD/COD
- Tertiary Treatment: Filtration for improving upon the results of earlier stages & removal of color.
Further, another stage of Advanced Treatment can be added as per the laws governing the industry in the area or as per availability of freshwater or ease of disposal of treated water. This stage has not been covered in this introductory document.
Typical Waste Water Treatment Flowsheet
| 1. Bar Screen | 2. Oil & Grease Traps | 3. Bqualization Sump | 4. Dosing Tanks |
| 5. Flocculator | 6. Primary Tube Settler | 7. MBBR | 8. EA Reactor |
| 9. Secondary Tube Settler | 10. Prefiltration Tank | 11. Pressure Sand Filter Vessel | 12. Activated Carbon Filter Vessel |
| 13. Sludge Tank | 14. Air Blower | 15. Raw Effluent Lift Pump | 16. Dosing Pump |
| 17. Sludge Recirculation | 18. Filtration Pump | 19. Filter Press Feed Pump | 20. Filter Press |
Characteristics of Untreated Discharged Water
| Type | Cotton Waste Water | Acrylic & Polyester Waste Water |
|---|---|---|
| Parameters | Parameters | Concentration |
| Temperature | Ambient | Ambient |
| pH | 7.0-8.0 | 6.0-6.5 |
| TSS | 200-300 mgl | 200-300 mgl |
| TDS | 1500-1800 mgl | 800-1000 mgl |
| BOD | 300-400 mgl | 150-200 mgl |
| COD | 800-1000 mgl | 400-500 mgl |
Characteristics After Treatment of Water
| Temperature | Ambient |
|---|---|
| pH | 5.5-9.0 |
| TSS | <100 mgl |
| TDS | <2100 mgl |
| BOD | 30 mgl |
| COD | <250 mgl |
Typical Water Consumption in Dyeing
| Type | Consumption |
|---|---|
| Acrylic Yarn Dyeing | 80 L/KG |
| Polyester Fabrics | 35 L/KG |
| Cotton Fabrics | 120 L/KG |
Different Stages of Treatment: Primary Treatment
Primary Treatment involves Physico-chemical treatment of influent to reduce TSS and colour from wastewater. COD of water is also reduced to some extent in this stage.
Different Stages of Treatment: Secondary Treatment
Secondary Treatment involves biological treatment of water from the first stage. This leads to a reduction of BOD & COD to desired levels.
Different Stages of Treatment: Tertiary Treatment
Tertiary Treatment is basically Filtration consisting of a Pressure Sand Filter & Activated Carbon Filter. They improve upon the parameters achieved in previous stages of treatment.
Typical Layout of a Biological Treatment Based Effluent Treatment Plant
| 1. Bar Screen | 2. Oil & Grease Traps | 3. Bqualization Sump | 4. Dosing Tanks |
| 5. Flocculator | 6. Primary Tube Settler | 7. MBBR | 8. EA Reactor |
| 9. Secondary Tube Settler | 10. Prefiltration Tank | 11. Pressure Sand Filter Vessel | 12. Activated Carbon Filter Vessel |
| 13. Sludge Tank | 14. Air Blower | 15. Raw Effluent Lift Pump | 16. Dosing Pump |
| 17. Sludge Recirculation | 18. Filtration Pump | 19. Filter Press Feed Pump | 20. Filter Press |