Project Presentation - Universit by fjhuangjun


									CLEANER TEXTILE PRODUCTION                              DANCED Project office
                                                        c/o Pollution Research Group
                                                        Chemical Engineering
                                                        University of Natal
                                                        Durban, 4041

                                                        Tel. +27 31 260 3561
                                                        Fax. +27 31 260 1118

Practical options that have been implemented at textile factories to make
      them cleaner, reduce effluent and air emissions and improve their
                              processing times


                              Project partners:
Improved process control

                   Fully integrated dye
                      vessel control in the
                      dyehouse by means of
                      Arel Control system.
                      Ensures proper usage
                      of water, steam,
                      cooling water etc
New cleaner technology
                   Replacing old winches that run at
Before…                liquor ratios up to 30:1 with
                       modern air jet dyeing machines
                       that run at about 5:1, results in
                       savings in water, energy and
                       chemicals. Reductions in water
                       and effluent of up to 80% may be

Improved stenter process control
                   Improving the process controls on
                       older equipment helps realise
                       cost savings, improvements in
                       production and reduction in
                       processing time without
                       having to invest in new
                       equipment. Here, a Mahlo
                       control system optimises the
                       dwell time of the fabric
                       through the stenter by
                       maintaining a steady
                       temperature profile throughout
                       the stenter. Each chamber has
                       an optical pyrometer at the top
                       to measure the temperature of
                       the fabric as it passes through
                       the stenter.
Automatic washing of drums
                 Drum washing in the
                   printing section of a
                   dyehouse – fully
                   automated with fresh
                   water additions
                   controlled by a timer
                   and solenoid valve.
                   Savings of up to 20%
                   in water and effluent.
New dyeing technology
                   Airstream jet running at liquor ratio of
                       between 1:3 and 1:5 have
                       replaced older dyeing machines at
                       this factory.

                   The following *potential savings are
                       possible by changing from 1:15
                       machine to 1:5 jet:

                       effluent: 582 000 kl/yr
                       Steam: 15 000 tonnes/yr
                       Salt (60 g/L): 1000 tonnes/yr

                   *producing 5 tonnes/day, 330
Adjusting pump on Jets
                 The pump on the Jet
                   dyeing machine at
                   this factory has been
                   lowered by about
                   15cm, thereby
                   lowering the water
                   circulation, and
                   lowering the liquor
                   ratio for the dyeing.
Automatic chemical dispensing
                    A small commission
                       dyehouse has installed
                       automatic dispensing of
                       caustic soda lye to the
                       dye machines. Ensures no
                       risks of spills, leakages
                       and injury to operators.
                       No risk of effluent from
                       clean-ups and costs of
                       cleaning spills.
Automatic chemical dispensing

            Fully automated dispensing
                of chemicals to dye
                machines eliminates
                spills, wastage and
                injury. Reduces risk to
                environment. Cost
                savings associated with
                clean-up operations for
                spills and leakages in
                manual additions.
New treatment for boiler feed water

                     A large cotton dyeing and printing
                         factory has installed a
                         chemical-free system for
                         softening feed water to the
                         boiler. The magnetic device
                         removes Ca2+ and Mg2+ ions in
                         a magnetic field. No chemicals
                         are needed. In this case, cost
                         savings of about R31000 per
                         annum have been achieved,
                         together with savings in make-
                         up water for the chemicals.
Better removal of print pastes
                    Improving removal of print pastes
                        from the screen reduces the
                        amount of water needed in the
                        cleaning operation. Operators
                        at this factory uses scrapers to
                        remove excess print pastes,this
                        removes as much paste as
                        possible before screen
                        washing. Less water is used in
                        the rinsing, and less effluent is
                        produced. Here, the water
                        addition is also controlled by a
Automatic screen washing
                  Fully automated screen
                     washing in the
                     printing section of the
                     dyehouse. Rinse
                     water is controlled by
                     a timer. Savings in
                     water and effluent of
                     about 30% have been
Reusing printing wash-water
                    Large amounts of water is
                       used in washing printed
                       blanket fabrics. Here, a
                       sump has been
                       constructed beneath the
                       washing line to collect
                       wash-water that is of an
                       adequate quality to be re-
                       used in washing-off the
                       blanket fabric after
                       printing. The sump has a
                       capacity of about 3 cubic
Reusing printing wash-water

                     The wash-water from the
                        sump is pumped through
                        a filter back to the
                        printing line to be re-used
                        in washing off printed
                        blanket material. Savings
                        in water and effluent of
                        90% achieved (based on
                        original fresh water
                        consumption before
                        reusing wash-water).
Pump        Filter                           Cont…
Reusing printing wash-water
                   A solenoid valve and
                      timer controls the
                      addition of fresh
                      water to the washing
                      line. In this way,
                      consumption of fresh
                      water is optimised,
                      and the re-use of
                      wash-water is at an
                      optimal level.
Modifying Jet clean-out…
                  Previously, Jet machines like this
                      one were flooded with clean
                      water after a clean-out, to rinse
                      the machine before the next
                      dyeing. Here, the Jet is being
                      rinsed with a hose-pipe with a
                      manually activated spray-
                      nozzle. In this way, the rinse
                      uses about 50 litres of water,
                      rather than 3 700, realising a
                      saving of approximately 7.3 kl
                      per cleaning in water and
                      effluent. Annual reductions in
                      fresh water consumption of
                      about 260 kl have been

Modifying Jet clean-out
                 This is the amount of
                    formic acid saved by
                    reducing the previous
                    double-clean out after
                    each dyeing and
                    nuetralisation, before
                    the next dyeing.
                    Positive impact by
                    reducing volume and
                    COD of effluent.
Displacer in dye pad trough
                  Not clearly visible here, is a
                     displacing unit built into
                     the trough, to reduce the
                     dead volume, so that the
                     amount of dye left at the
                     end of the batch is
                     reduced by about 32%.
                     Less water is used, and
                     the time for mixing the
                     dyes and chemicals has
                     also been shortened.
Reducing cooling water flow
                   A solenoid valve and timer
                      controlled by a central
                      Arel system controls the
                      flowrate of cooling water
                      through the Then Airjet
                      dyeing machine. Cooling
                      water flow is optimised,
                      resulting in savings in
                      water and cooling-water
                      treatment chemicals.
Recovering heat from exhaust air
                    Heat exchangers consisting of
                        bundles of glass tubes recover
                        heat from the hot stenter
                        exhaust. This is used to heat-
                        up the incoming cool air. In
                        this way, the energy
                        consumption is reduced and
                        less CO2, SO2 and NOx
                        released to atmosphere. In this
                        case, about 40 degrees of heat
                        is recovered, resulting in a
                        reduction in thermal fuel of
                        about 40%.
 Heat exchange
                                      Dyebath effluent has a high heat
                                         content, that may be recovered to
                                         heat up boiler feed water or
                                         process water used for hot rinses.
                                         Generally every 1 degree
                                         recovered saves 1% of boiler

In this case, dyebath effluent is
    used to heat the incoming water
    to about 60 degrees celsius.
    This has reduced boiler fuel
    consumption by 20%, CO2
    emissions by 543 tonnes/year
    and SO2 emissions by 2.50
Solid waste management
                   Sorting and collecting fabric
                      wastes at source in the
                      factory makes solid waste
                      management easier. In
                      this case, the fabric waste
                      is collected and stored
                      on-site. The fabric waste
                      is then sold to a waste

Solid waste management

            Plastic, cloth, cardboard,
                 fluff, cone and drum
                   wastes have been
                   segregated in the
                factory and assembled
                   at this point. This
               ensures that all sources
               of wastes are accounted
                 for, and that the solid
                 wastes are handled in
               the proper manner. The
              wastes are collected and
                     recycled by an
                  independent waste
Solid Waste Management: before
                     Textile factories produce large
                         amounts of solid wastes:
                         Yarn and fabric waste
                         Plastic wastes
                         Cardboard wastes

                     These wastes are often dumped at
                         municipal dumping grounds or
                         landfill sites through waste
Solid Waste Management: before…
                   A large portion of the solid
                       wastes from textile
                       factories is made up of
                       cardboard packaging,
                       plastic wrappers and
                       tapes. These are simply
                       dumped at municipal
                   Local people then sift
                       through these wastes to
                       collect any material they
                       might find useful.

Solid Waste Management: before…
                                            The solid wastes dumped at
                                                municipal sites is then
                                                “scavenged” for any useful
                                                material. Here, the fabric
                                                wastes are being sorted and
                                                collected by locals.

This is dangerous and poses severe health
and safety risks to these people.

Solid Waste Management: after…

                   The factory has now
                      separated all solid wastes
                      at source, through a
                      collection system in each
                      department of the factory.
                      These are then collected
                      and used by a recycling
                      company. This has
                      reduced the solid waste
                      burden of this factory by
                      a significant amount

Solid Waste Management: after
                    At this factory all fabric
                       and yarn wastes are
                       separated at source,
                       weighed and stored in
                       a central holding area.
                       Recyclers then
                       purchase this material
                       for a variety of end
Chemical Leak and Spill Handling
                    Proper management of
                       chemical leaks and spills
                       demonstrates environmental
                       responsibility. A system for
                       cleaning up leaks and spills
                       also saves the company
                       money that would have
                       been spent on costly clean-
                       ups and fines. The health
                       and safety of factory
                       workers are also improved.
Chemical Drum Reuse
                  Chemical drums are often
                     sent for disposal together
                     with the general solid
                     wastes. In this factory, all
                     the used drums are
                     collected and stored at a
                     central point. The
                     chemical suppliers then
                     collect the drums for re-
                     conditioning and reuse
                     for some other purpose.
Chemical Leak and Spill Handling

                    Signage is important for
                       workers handling
                       dangerous bulk
                       chemicals. At this
                       factory, the correct work
                       instructions for the
                       chemical handling, and
                       off-loading process has
                       been written near the
                       bulk tank to prevent
                       accidents to workers,
                       spills and dangerous
Caustic recovery from mercerising
                    At this factory, caustic effluent from
                         the mercerizing range is pumped
                         through a series of evaporators to
                         concentrate the effluent. This
                         concentrate is then reused in the
                         mercerizing range. About 11
                         tonnes/day of caustic is
                         recovered, realising significant
                         cost savings (about R14000/day)
                         and reduction in effluent
                         pollution load.
Reusing cooling water
                 At this large fully integrated mill,
                      dyeing and printing cotton,
                      cooling water is recycled to
                      this tank from where it is
                      pumped out to the various
                      process cooling water users.
                      Savings in fresh water of
                      50m3/day, treatment chemicals
                      and effluent has been realised.
Heat exchange   The pictures here show how hot
                    dyebath effluent is used to heat
                    incoming process water to about
                    70 DegC in a baffled heat
                    exchanger. On a daily basis this
                    represents a saving of about
                    12000 kWh of energy. For an
                    HFO fired boiler, this represents a
                    cost saving of about R1200/day,
                    and reductions in emissions of
                    about 14 kg SO2 per day, and
                    3044 kg CO2 per day.
Heat recovery from mercerizing
              The pictures here show a pipe heat exchanger
                  with a bundle of tubes that is used to heat
                  process water, through recovering heat from
                  the mercerizing effluent. About 20 DegC is
                  recovered, representing a saving of about
                  20% in boiler fuel. About 3510 kWh/day is
                  saved, reducing HFO consumption by about
                  297 litres/day. This represents a cost saving
                  of about R356/day, and reduction in SO2
                  emissions of 4 kg/day, and CO2 emissions of
                  890 kg/day.
Condensate recovery and reuse

                  A marked piping system has been
                     constructed around this Combi
                     steamer, where recovered
                     condensate is reused as hot
                     process water in the dye works.
                     Roughly 250 kl/day, is recovered.
                     Savings in water and effluent of
                     about 500 kl/day has been
Waste segregation at source

                     At a large factory that
                         processes woven cotton,
                         cone and fabric wastes
                         are separated at source,
                         and assembled at a
                         central point outside the
                         production area the
                         factory. On a monthly
                         basis about 20 tonnes of
                         fabric waste is recycled.
                         The solid wastes is sold
                         to recyclers.
Reusing effluent for screen washing
                    A large dyeing and printing
                        company segregates
                        effluent at source. The
                        relatively low strength
                        effluent is then pumped
                        to a storage tank, from
                        where the water is reused
                        in washing print screens.
                        Significant savings in
                        water of 10 m3/day and
                        effluent has been
Sorting and recycling solid wastes

                     This factory separates
                        and collects cone,
                        drum and tube waste
                        at source, and
                        assembles them at a
                        central point. The
                        waste is then recycled
                        to the suppliers.
                     On a monthly basis, 153
                        drums are recycled.
Recycling general wastes
                    Plastic, cardboard and
                       packaging waste has been
                       separated at source within
                       this factory. The waste is
                       then assembled at a central
                       collection point, and sold to
                       recycling companies.
                    Plastic: 3.026 tonnes/month
                    Cardboard cores: 18.11 tonnes/month
                    Packaging: 11.7 tonnes/month
Recycling fabric wastes
                    Yarn wastes and fabric off-
                       cuts have been sorted and
                       collected at source at this
                       factory. The wastes are
                       then assembled at a
                       central collection point,
                       where it is weighed and
                       sold to recycling
                    Yarn waste: 25 tonnes/month
                    Fabric waste: 20 tonnes/month
Reducing wastes from carpet weaving
                             A large carpet manufacturer has separated wastes from the
                                 weaving process at source, and assembled the wastes at
                                 a central point for recycling.
                             The Spool setting and Spool gripping in the weaving
                                 process produces the most amount of solid wastes in
                                 this factory.

Waste collection for recycling

Waste collection from Spool weaving                Waste collection from spool setting
Recycling solid wastes
                                                General waste, oil waste and
                                                   metal wastes are collected
                                                   at source at a large carpet
                                                   manufacturer. These
                                                   wastes are then assembled
                                                   at a central collection
                                                   point for recycling
Separation at source

Recycling oil wastes   Recycling metal wastes
CP audit course…
                   An audit course for training auditors in
                       waste minimisation was
                       successfully completed at the
                       University of Natal, Durban. The
                       course was attended by people
                       from industry, consultants, research
                       institutes and textile education
                       organisations. The course is being
                       presented by Susan Barclay,
                       Pollution Research Group –
                       University of Natal from June to
                       November 2000
CP audit course…
                   The course consisted of 8 modules,
                       each having theoretical and
                       practical component. Course
                       participants completed each
                       module at the University, and
                       then completed the practical
                       auditing at a factory in
                       Durban. They then provided
                       regular progress reports at
                       each training session. Each
                       participant will be awarded
                       with a University accredited
                       certificate on successful
                       completion of a the final report
CP audit course
                                     The overwhelming success of this
                                         training has prompted the course
                                         organizers to give a second
                                         identical course in Cape Town.
                                         The details are as follows:

                                       Contact: SUSAN BARCLAY
                                                Pollution Research Group
                                                Tel. 031-2603375
                                       Course diary
                                       Module 1: 6 and 7 November 2001
                                       Module 2: 27 and 28 November 2001
   The course participants, Durban     Module 3: 4 and 5 February 2002
                                       Module 4: 25 and 26 February 2001
                                       Module 5: 20 March 2002
Chemical Score system
                                                                                      An important outcome of the study
                                                                                          tour was the specific request from
                                               Chemical Score Chart                       local industry for assistance in
                                                                                          implementing a chemical score
                                                                                          system for our industry. The
Exposure Score, A.B.C

                                                                           Bad scores
                        50                                                                score system is a management
                                                                                          system for ranking chemicals
                                                                                          according to their use,
                        10                                                                biodegradability,
                             Good scores                                                  bioaccumulation and toxicity. A
                             0             1               2           3              4   pilot project is currently being run
                                                   Toxicity Score, D                      for Durban factories by a visiting
                                                                                          Danish expert and students. This
   A: amount used                                                                         project is due to be completed by
   B: biodegradability                                                                    December 2001, and would have
   C: bioaccumulation                                                                     resulted in compiling the Score
   D: toxicity                                                                            reports for 10 local factories. The
   The exposure score is calculated by A*B*C,                                             project also aims to promote
   then compared with D on an XY system of
   coordinates to provide an overall score.
                                                                                          interaction between chemical
                                                                                          suppliers, factories and local
                                                                                          regulatory bodies.
                        Score system in practice
                   56                                         The score report on
Exposure (AxBxC)

                                                              Exposure and Toxicity
                                                              effects of each
                   24                                         chemical used in the
                   16                                         production process.
                        0   1          2           3      4
                                D1 Score (Fauna)

                                                                A large carpet manufacturer
                                    The chemicals                   has now incorporated the
                                    with the worst                  Score system for
                                    scores have been
                                    separated and                   environmental ranking of
                                    marked for more                 chemicals into their overall
                                    investigations, and             chemical management
                                    possible                        programme.
Study tours to Denmark
                                            A study tour to Denmark has
                                                increased awareness in CP in
                                                the SA textile pipeline,
                                                promoted interchange of
                                                information on specific
                                                practices related to CP in
                                                cotton exhaust reactive dyeing,
                                                and helped overcome
                                                management barriers to
                                                implementing CP in local
                                                dyehouses. In November 2000,
                                                top management
                                                representatives from the local
 Study tour group: 14 to 25 November 2000
                                                industry and government
                                                departments undertook a study
                                                tour of factories, government
                                                departments and educational
                                                institutions in Denmark.
Study tours to Denmark
                    Key players from the SA textile
                        manufacturing industry
                        observed CP practices in
                        Danish dyehouses, learned
                        about the Danish experience in
                        implementing their CP
                        programme and visited
                        regulatory councils and
                        municipal treatment works.
                        This has helped to overcome
                        barriers to implementing CP in
                        SA factories. All the factories
                        represented in this tour have
                        now implemented CP options
                        related to reducing water and
                        effluent in the dyeing and
                        washing-off of cotton

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