Environmental Textiles

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"Nature maintained a remarkable balance in the ecosystem until man-induced industrial metabolism meddled with it."
Benchmark Studies for Raw Materials wastes in Textiles Mills (Abstracts from a study conducted by Unido)
Dyeing and printing	Wool finishing process	Wool Scouring	Woven Fabrics Finishing	Yarn Finishing

Raw Materials and Wastes for Wool Scouring Mill Processes

Table 1: Wool Scouring Mill Basis: 1 tonne of scoured wool

PROCESS INPUTS WASTES

Raw materials Water Energy Liquid Solid Gas

Sorting & blending Wool 1300-4000 Kg (1) Electricity

Scouring Soap, Sodium Carbonate 30-50 m³ (3) Electricity, Steam pH 9.0-10.4, BOD 104.5-221.4 Kg , TS 1129-64448 ppm (2), FLOW 20-50 m³ (3) N.A.

Drying Electricity, Steam Vapours, Particulate

Top making Electricity N.A.

(1) According to the literature reviewed, raw sheep wool contains from 25 to 75% suint, which includes water soluble excretions of the sheep such as urine, feces, blood, dirt, grease, etc. From this data, the amount of raw wool needed to obtain 1 tonne of scoured wool has been calculated.

(2) Due to the high amount of organic impurities present in raw wool, the scouring process contributes to more than half or even up to two-thirds of pollution load in terms of BOD . From the scour liquor, lanolin can be recovered by acid cracking or centrifugation. Lanolin recovery reduces BOD by 20-30%. Also suint can be recovered and sold for detergent manufacture reducing BOD by another 20-30% .

(3) Tables 1.1 and 1.2 give the water consumption and pollution load for wool scouring mills as extracted from reference . As can be seen, the water consumption range for the scouring stage given in reference is consistent with the data from reference , but the BOD reported in the former is higher. Differences might be due to the recovery of lanolin from the scouring effluent. According to the flow diagrams presented in reference 10, it seems that lanolin recovery is included as a part of the process. However, whether lanolin recovery is considered or not in reference it can not be assured from the description given.

Table 1.1: Amounts of water typically used in Wool Scouring Mills

Units: m³/t of scoured wool

Minimum Median Maximum

4.2 11.7 77.6

Table 1.2: Characteristics of Wool Scouring Effluents and Amounts of Waste Load Generated (median values) [10]

Units BOD COD TSS O&G Phenol Cr Sulphide

mg/l 6000 30000 8000 5500 1.5 0.05 0.2

Kg/t 41.8 128.9 43.1 10.3 N.A. N.A. N.A.