INTERNATIONAL CLEANER PRODUCTION INFORMATION CLEARINGHOUSE

CASE STUDY #18
1.   Headline: Conserving water, energy and chemicals at a
textile dyeing plant.
2.   Background: The textile dyeing process used at the
Hitega textile mill in Chile involves numerous changes of
water, and several additions of dyes, bleaches and other
chemicals. As part of the Environmental Pollution Prevention
Project (EP3) sponsored by the US Agency for International
Development, a cleaner production assessment was carried out at
the facility by an expert in textile dyeing and a pollution
prevention specialist.
     The assessment identified eight opportunities which would
     reduce:
          - water use           - chemical use
          - energy use          - emissions
          - suspended solids
            concentration in wastewater.
     Hilados y Tejidos Garib S.A. (Hitega) is an integrated
textile mill producing dyed yarn and fabric with an average
content of 65 per cent polyester and 35 per cent rayon. It
employs 270 people, and in 1993, produced     1 134 059 kg of
dyed material, and an additional        1 227 974 kg of fabric
that was finished but not dyed.
3.   Cleaner Production Principle: Internal recycling,
     process modification
4.   Description of Cleaner Production Application:
     Efficient use of water:
     Recycling of cone-dye cooling water:  Well water is
softened to a hardness of 3-5 ppm, and is then used  for most
factory processes. During the cone-dyeing operation, the dye
bath is cooled by passing soft water through the jacket of the
dye tank. Non-contact cooling water is also used to cool the
dye bath recirculating pump packing gland. Recycling these two
streams of water can be accomplished by sending this non-
contact cooling water back to the soft water pool, which
receives the cooling water from facility jet dryers.
     Recycling water from the air conditioner system:  The air
conditioner system used in the spinning and weaving rooms also
uses soft water evaporation for cooling. The water is currently
taken from the softeners serving the dye room, but 50 per cent
of this is lost through evaporation, and the rest is dumped
into the sewer system. This has caused water shortages in the
dye room. New softeners are being installed to produce water
solely for the air conditioner system, which will recycle the
non-evaporation water back to the new system.
     Improving softener regeneration and service:  During the
     washing, regeneration and rinsing processes in the dye
     room, the wash time is currently excessive, and the point
     at which softeners are regenerated is chosen on the basis
     of time since the last regeneration. This results in a
     loss of soft water. A digital system would enable the
     rinsing and service hardness end points to be determined,
     allowing operators to judge more accurately the exact end
     point for the wash period and the maximal supply capacity
     of each softener.  Rinse waters can also be recycled from
     the bleaching process , by installing a tank to store the
     water from one batch and using it for the one that
     follows.
     Efficiency use of energy
     Maintenance plan for steam traps:  Heat transfer losses
     caused by leaking steam traps currently amount to around
     10-1 per cent of energy costs. Leaking steam traps not
     only waste energy, but also result in inefficient dye
     bath heating, and damage to steam lines, valves,
     fittings, and other equipment. Workers should be trained
     in the operation of steam trap testing equipment, and a
     preventive plan for the maintenance of steam traps should
     de developed.  Installation of a digital monitoring
     system allowed the combustion efficiency of the oil-fired
     boiler to be monitored whenever parameters change - such
     as when a new lot of oil is received. This change
     resulted in reductions in fuel use and emissions of
     particulate matter.
     Reducing suspended solids in effluent:  Screens
     installed in dye room drains reduce suspended solids in
     effluent. If the plant needs to install an industrial
     waste water treatment system in the future, any decrease
     in current loading will allow a reduction in the initial
     investment and running costs of such treatment plant.
5.   Economics:
     Operation            Saving       Payback
                  Cost (US$)     (US$/year)     period
     Recycling of
     dye cooling
       water          750       400        20 months
     Recycling of
     air conditioning
     System water     6 700     4 900        14 months
     Softener system    3 5001 700        24 months
6.   Advantages: The implementation of these suggestions will
     result in water, energy and chemical conservation,
     reduced emissions and solids in effluent. Three of the
     opportunities  were studied in enough detail to quantify
     savings, as shown above.
7.   Constraints: N/A
8.   Contacts:Mr Carlos Kanterovitz
                  Hilados y Tejidos Garib S.A
                  Rodrigo de Araya No.951
                  Macul Santiago
                  Chile
                  Tel: +56 2 238 4007
                  Fax: +56 2 238 5091
                  Maurice Knight
                  Core Program Manager for Chile
                  EP3
                  RCG/Hagler Bailly, Inc
                  1525 Wilson Bd
                  Suite 750
                  Arlington, Va 2209-2406
                  USA
                  Tel: +1 703 351 8166
                  Fax: +1 703 351 6166
9.   Keywords:  Chile, USAID, textile, dyeing, recycling, good
     housekeeping, cone dyeing, air conditioning, water
     saving, EP3
10. Reviewer comments: This case study was originally
published in the UNEP IE document "Cleaner Production
Worldwide", Volume II. In the process of preparing the document
the case study underwent a technical review.