 |
Type of Dye |
Dye class |
Substrate |
pH |
BOD (mg/L) |
TOC (mg/L) |
COD (mg/L) |
TSS (mg/L) |
TDS (mg/L) |
ADMI
colour value |
Typical left-over dye % |
| Synthetic dyes |
Vat |
cotton |
12 |
294 |
265 |
NA |
41 |
3,945 |
1,910 |
5-20 |
| Reactive |
cotton |
11 |
NA |
150 |
NA |
32 |
12,500 |
3,890 |
20-50 |
| Azoic |
cotton |
9 |
200 |
170 |
NA |
387 |
10,900 |
2,415 |
5-10 |
| Natural dyes |
Vegetal |
cotton |
7-8.5 |
30-60 |
NA |
150-290 |
<1 |
1,500-2,000* |
No colour |
- |
| CPCB standards for discharge on land |
|
|
5.5-9.0 |
100 |
- |
- |
200 |
- |
Remove as practicable |
- |
|
| Key: |
| < – Less than |
BOD – Biological oxygen demand |
TOC – Total organic carbon |
| NA – Not Available |
COD – Chemical oxygen demand |
TSS – Total suspended solids |
| ADMI – American Dye Manufacturers Institute |
TDS – Total dissolved solids |
CPCB – Central Pollution Control Board, Government of India |
|
The figures for synthetic dyes have been taken from Manual: Best Management Practices for Pollution Prevention in the Textile Industry, U.S. Environmental Protection Agency. Sept 1996
The results for natural dyes have been taken from our own data and analysed by a certified laboratory. The vegetal extracts, mordants and soap/detergents were mixed, the sludge separated and the supernatant analysed.
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