Raw Materials and Wastes for Woven Fabric
Finishing Mill Processes
Table
4: Woven Fabric Finishing Basis: 1 tonne of woven
fabric
| PROCESS |
INPUTS |
WASTES |
| |
Raw materials |
Water |
Energy |
Liquid |
Solid |
Gas |
| Desizing |
Enzymes or H2SO4
Yarn |
2 m3 5 m3
(1) |
Steam 5 GJ (2) |
BOD 14.8-16.1 Kg 60 Kg TS
66-70 Kg FLOW 1-5 m3 (1) (2) |
|
Vapours |
| Scouring |
(3) |
10 m3 (1) |
Steam 5-11 GJ (2)(4) |
BOD 1.4-3.0 Kg TS 47-67 Kg
FLOW 9-20 m3 (1) |
|
|
| Mercerize |
NaOH, solution 10-30% by
weight |
90 m3 (10)(1) |
N.A. (2) |
pH 5.5-9.5 BOD 10.5-13.5Kg
TS 185-450 Kg FLOW 110-150m3 (1)(7)
|
|
|
| Bleach |
H2O2
or NaOCl |
1 m3 92-250 m3
(9) (1) |
Steam 10 GJ (2)(5) |
pH 8.5-9.6 BOD 5.0-15kg TS
38-290kg (1) FLOW 1-60m3 |
|
Vapours |
| Dyeing |
See Tables 9,10 |
See Table 8 (1) |
N.A.(2) |
Highly Variable (1) |
|
|
| Printing |
See Tables 9,10,11 |
14 m3 (1) |
N.A.(2) |
Highly Variable (1) |
|
VOC See Table 11 |
| Finishing
& drying |
Finishing agent |
0.02 m3 (1) |
1.9-3.7 GJ2.6-7.1 GJ (2)(6)
|
(1)(10) |
|
Vapours Particulate |
(1) Tables 4.1 and 4.2 list the amount
of water used and waste load for Woven Fabric
Finishing Mills.
(2) Total energy requirement for Woven Fabric
Finishing is about 18700 KWh per tonne of finished
fabric .
(3) There are two common methods of scouring:
Kier boil and continuous scouring. According to Lund
, the chemicals used to prepare the kier liquor for
the pressure kier boil are NaOH 10-80 Kg, Na2CO3
10-30 Kg, Na2SiO3
2.5-10 Kg, pine oil soap and fatty alcohol sulfates.
In continuous scouring, the goods as received from
the desize wash are passed through a caustic solution
(3-6% caustic soda plus wetting agent).
(4) Scouring process consumes about 5-6 GJ/t.
Subsequent washing-off requires a further 5 to 6 GJ/t
.
(5) The energy required for bleaching may
amount to 5 GJ/t. Washing-off is an important part of
the processing and again is found to require about 6
GJ/t according to reference .
(6) Energy required for drying only.
(7) According to Jones,, mercerization
produces an effluent containing 5% NaOH. The lower pH
figure given also in this reference seems too low if
the concentration of sodium hydroxide is taken into
account.
(8) As stated in reference this figure for
water consumption corresponds to mercerizing machines
with countercurrent washing.
(9) Reference contains a compilation of water
usage data for different industrial sectors and
operations. The differences in the data given are due
to the different sources from which they were
extracted and no explanation is given to justify the
wide variation.
(10) Finishing is normally a continuous
process that produces little or no wastewater .
Table 4.1: Amounts
of Water Typical in Woven Fabric Finishing Mills
Units: m3/t
of wool fabric
| Process Description |
Minimum |
Median |
Maximum |
| Simple |
12.5 |
78.4 |
275.2 |
| Complex |
10.8 |
86.7 |
276.9 |
| Complex+Desizing |
5.0 |
113.4 |
507.9 |
Table 4.2:
Characteristics of Woven Fabric Finishing
Effluents and Amounts of Waste Load Generated (median
values)
| Units |
Type of Process |
BOD |
COD |
TSS |
O&GG |
Phenol |
Cr |
Sulphide |
| mg/l |
Not Described |
650 |
1200 |
300 |
14 |
0.04 |
0.040 |
3.0 |
| Kg/t |
Simple (1) |
22.6 |
92.4 |
8.0 |
9.1 |
8.2 |
4.3 |
7.6 |
| Complex (2) |
32.7 |
110.6 |
9.6 |
3.8 |
7.7 |
2.6 |
12.5 |
| Complex + Desizing |
45.1 |
122.6 |
14.8 |
4.1 |
13.1 |
20.9 |
N.A. |
(1) Processes such as desizing,
fibre manufacturing preparation and dyeing.
(2) Simple manufacturing with additional
operations such as printing and dyeing.