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98 3.6 Re-use of treated dye-bath after reactive dyeing at a Danish dye-house, Martensens Fabrik John Hansen, DTI Clothing and Textile, Denmark Abstract Spent dye-bath is treated with activated carbon in order to remove residual dye-stuffs and other organic chemicals. The treated water is re-used for the new dye-bath including its content of salt, alkali and energy. Lab-scale tests with activated carbon The objective of these tests were to find the best types of activated carbon for this purpose. 12 different brands were tested in jar-tests. 4 Cibacron C or F dyes were used: Navy, Orange, Yellow and Red. The results can briefly be summarized as follows: • All the investigated reactive dyes can be removed using a proper amount of activated carbon • No environmentally harmful substances are introduced • Salt enhances the dye-adsorption on the activated carbon • Detergents and other organic chemicals are removed • The adsorption can be run at any temperature The method is, however, in general relatively expensive and should thus only be preferred when membrane filtration or other techniques are not feasible. This is the case with the dye-bath because of its very high salinity, The activated carbon adsorption is not negatively influenced by the salinity and furthermore allows for re-use of the salt. These advantages cannot be met by any of the other reclamation techniques and they outweigh the excess cost for activated carbon. Lab dyeing tests with water treated with activated carbon In a lab dyeing machine a large number of dyeing processes were tested, using waste-water from previous dyeing processes treated with activated carbon and in all cases in comparison to a normal dyeing process using normal process water. For each test-dyeing the results as well as fastness tests (rub, wash) were assessed. Good results were obtained with the following dye-stuffs: • Cibacron C, E and F • Drimaren X and B • Remazol • Sumifix Supra
The conclusion based on lab-scale results was that waste-water from reactive dyeing of cellulose can be treated with activated carbon to an extent, that the purified water can be re-used for the dye-bath with its content of salt, some alkali and energy. The results, however needed verification on a larger scale, and subsequently semifull-scale and full-scale tests were therefore conducted. Semi-full-scale activated carbon treatment plant Investigations were carried out with a semi-full-scale activated carbon treatment plant, comprising two 400 1 serial tanks and working with a capacity of 400 l/h. Retention time, thus, 1 h per tank. More than 10 m 3 have been run through the plant without reaching the adsorption capacity of the carbon. Full-scale test dyeings A series of test dyeings have been carried out at the dye-house on small but ordinary production machines. Approx. 25 kg of cotton knitwear were dyed with a liquor ratio of between 1:14 and 1:16. The water for the dye-baths came from former exhausted dye-baths plus some first rinsing baths after a treatment in the activated carbon plant. The following types of dye-stuffs were used: • Remazol • Cibacron C and F • Drimaren X In all cases, the results of the dyeings were tested by the dye-house staff. In all cases the dyeings were accepted and normal fastness levels were reached. The lots were delivered to – and accepted by – the custumers. As the purified waste-water to be used as process water contains salt and alkali, measurements must be carried out of salinity and pH before adjusting the amounts of salt and alkali. Typical amounts and savings are shown below: Normal procedure g/l Test procedure g/1 Savings g/1 Salt 80 72 8 Soda 5 0 5 NaOH 2 2 0 In these cases the treated water contained a lot of rinsing water from the first rinse which is the reason for the relatively low savings in salt consumption. Normally this saving would be much larger. As the treated water is already heated, there will also be a considerable saving in energy and production time. 99
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1999 Cleaner Technology Transfer to
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Content Preface 5 Summary 7 Part 1.
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Summary Areas of pollution preventi
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1.1 Programme description Programme
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Focus on cost-effective options par
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2.1 Introduction This Idea catalogu
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Topic 1. Minimization in consumptio
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Topic 3. Optimization of cooling by
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Topic 5. Temperature control of coo
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Topic 7. Minimization of water for
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Topic 9. Exchange of batch dyeing m
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Topic 11. Introduction of in situ r
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Topic 13. Optimization of counter c
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Topic 15. Procedure for cleaning of
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Topic 17. Change from batch to cont
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Topic 19. Desizing with enzymes Cas
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Topic 21. Substitution of APEO dete
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Topic 23. Change from monoreactive
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Topic 25. Substitution of carriers
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Topic 27. Substitution of afterchro
Page 47 and 48: Topic 29. Dry conditioning Case ill
Page 49 and 50: Topic 31. Mechanical softening proc
Page 51 and 52: Topic 33. Re-use of pure cooling wa
Page 53 and 54: Topic 35. Re-use of chemically load
Page 55 and 56: Topic 37. Re-use of water from rins
Page 57 and 58: Topic 39. Separation techniques for
Page 59: Topic 41. Evaporation and reclamati
Page 63 and 64: 3.1 Introduction During the Cleaner
Page 65 and 66: The ever increasing demand to shade
Page 67 and 68: The dyeing process The reactive dye
Page 69 and 70: hardness in water and extract from
Page 71 and 72: Figure 7. The effect of complexing
Page 73 and 74: Reduced process time Seilund and C.
Page 75 and 76: Tabel 1. Degradation af APEO. Table
Page 77 and 78: Alkylphenol ethoxylates (APEO) This
Page 79 and 80: 3.4 Reclamation and re-use of proce
Page 81 and 82: Figure 1. Typical process waters fr
Page 83 and 84: Figure 2. The dependency of precipi
Page 85 and 86: Advantages and limitations of the w
Page 87 and 88: Figure 5. Environmental benefits of
Page 89 and 90: Kolb, M., B. Funke, H.P. Gerber and
Page 91 and 92: Figure 3. Typical process water fro
Page 93 and 94: Table 1. Selected chemical for delc
Page 95 and 96: Figure 9. Profiles for dye-stuff pr
Page 97: Conclusions The optimal use of chem
Page 101 and 102: During the period from 1992 to 1995
Page 103 and 104: 3.8 Environmental labelling John Ha
Page 105 and 106: The products to be labelled with th
Page 107 and 108: 3.9 Improvement of the rinsing effi
Page 109 and 110: Table 1. Documentation of savings i
Page 111 and 112: Part 4. Implementation projects 111
Page 113 and 114: 4.1 Introduction On the basis of th
Page 115 and 116: and a continued pumping is achieved
Page 117 and 118: The new recipes were tested in a la
Page 119 and 120: 4.4 Savings and substitution of env
Page 121 and 122: To illustrate the order of magnitud
Page 123 and 124: Data sheet Publisher: Ministry of E
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