Page 75 - Materials Chemistry, Second Edition

Ch002-P373623.qxd 3/22/07 5:27 PM Page 56
Sustainable Industrial Design and Waste Management
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TABLE 2.21
Effluent Characteristics Before and After Implementation*
Concentration (mg/1) El-Nasr Dakahleya AmirTex
Gray Black Black Black
Sulfide
Before 68 117 40 103
After 1 2.5 0.7 1.5
Hexavalent chromium
Before 26 27 n/a Nil
After Nil Nil n/a Nil
BOD
Before 360 540 347 660
After 1,275 2,150 1,233 1,070
TDS
Before 3,385 3,900 1,510 –
After 2,690 3,450 1,950 –

* From the end of the dyeing line.

TABLE 2.22
Benefits and Achievements
El-Nasr Dakahleya AmirTex
Electricity consumption reduced by: 22% 38% 8%
Steam consumption reduced by: 16% 39% 21%
Chemical costs reduced (increased) by: 2% (6%) 4%
Water consumption reduced by: 13% 39% 15%
Labor costs reduced by: 23% 57% 6%
Processing time reduced by: 22% 38% 6%
Other achievements include:
• Improved productivity
• Improved working conditions
• Phasing out of toxic sodium sulfide and
acidified dichromate

Textile sector: Combining preparatory processes in textile
companies
Sizing is a very important process in the textile industry to increase the ten-
sile strength of threads and reduce fiber breakages during the weaving process.
This process can be done by coating the threads with a “size”/“starch”.
“Desizing”, either with acid or enzymes, then removes size from the fabric, so
that chemical penetration of the fabric in later stages is not inhibited. Desizing,
scouring, and bleaching are always used in spinning and weaving wet processes.