Textile dyeing in Mali : possibilities for small scale effluent treatment
Water treatment is an important issue in Mali, an arid country where the Niger River is the main recipient for a large part of the effluents from industrial and small scale activities. Clothes dyed with synthetic dyestuffs are an important part of the culture in Mali. Dyeing of textiles is to a larg...
| Autor principal: | |
|---|---|
| Formato: | H2 |
| Lenguaje: | Inglés francés |
| Publicado: |
SLU/Dept. of Soil and Environment
2009
|
| Materias: |
| _version_ | 1855570205745348608 |
|---|---|
| author | Larsson, Hanna |
| author_browse | Larsson, Hanna |
| author_facet | Larsson, Hanna |
| author_sort | Larsson, Hanna |
| collection | Epsilon Archive for Student Projects |
| description | Water treatment is an important issue in Mali, an arid country where the Niger River is the main
recipient for a large part of the effluents from industrial and small scale activities. Clothes dyed with
synthetic dyestuffs are an important part of the culture in Mali. Dyeing of textiles is to a large extent
an informal activity, mainly performed by women.
The objective for this thesis work was to investigate potential capacity of cheap, locally accessible
materials in treatment of effluents from textile dyeing. Effluents studied were sampled at three sites
with small scale textile dyeing in Bamako, Mali. At two sites the effluents were emitted directly to
the Niger River, at the third site the effluents were collected in a soakaway. The capacity of different
materials, both coagulants and adsorbents, to treat the effluents was analysed with jar tests. pH,
conductivity, total dissolved solids (TDS), turbidity and dissolved oxygen (DO) were analysed on
samples before and after jar tests, and on river water from spilling site. For some jar tests, UV-Vis
spectra and content of zinc, nickel and copper were analysed. Properties of dyestuffs were analysed
with spectrophotometry, scanning electron microscopy (SEM) and nuclear magnetic resonance
spectroscopy (NMR).
Iron(III) chloride coagulated dye effluents, efficiently removing most of the colour from water.
Activated carbon, both in granulated form and in the form of powder, showed some capacity to
adsorb compounds in dye effluents. Rice chaff, rice bran, laterite, bentonite and aluminium sulfate
did not show capacity to remove dyes from effluents.
The composition of the dyestuffs used in small scale dyeing is not known, which is a serious
problem when developing treatment methods. A significant fraction of the dyestuffs consists of
substances which are not part of the colour-yielding dye. Five dyestuffs with different colours were
analysed with SEM with X-ray fluorescence detector. These dyestuffs contained, except for carbon,
oxygen and nitrogen which can not be detected, mainly sulfur, chloride, sodium and, in the case of
green, barium. Traces of chromium, vanadium, iron, aluminium and silicon were also detected in
some of the dyestuffs. Mixed effluents from two sampling sites contained concentrations of zinc
and nickel higher than WHO guideline values for drinking water.
Further studies are needed to find a cheap treatment method since low cost materials such as
rice bran and laterite are ineffective. In addition to be able to remove polluting substances from dye
effluents, the method should include cheap and readily accessible materials, and be supported by an
infra-structure which allows the effluents to be treated locally. To find a working solution to decrease
water pollution, without threatening the livelihood for dyers, co-operation between universities,
dyers and governmental bodies is crucial. |
| format | H2 |
| id | RepoSLU594 |
| institution | Swedish University of Agricultural Sciences |
| language | Inglés fre |
| publishDate | 2009 |
| publishDateSort | 2009 |
| publisher | SLU/Dept. of Soil and Environment |
| publisherStr | SLU/Dept. of Soil and Environment |
| record_format | eprints |
| spelling | RepoSLU5942012-04-20T14:10:13Z Textile dyeing in Mali : possibilities for small scale effluent treatment Larsson, Hanna water treatment textile dyes artisanal Mali Water treatment is an important issue in Mali, an arid country where the Niger River is the main recipient for a large part of the effluents from industrial and small scale activities. Clothes dyed with synthetic dyestuffs are an important part of the culture in Mali. Dyeing of textiles is to a large extent an informal activity, mainly performed by women. The objective for this thesis work was to investigate potential capacity of cheap, locally accessible materials in treatment of effluents from textile dyeing. Effluents studied were sampled at three sites with small scale textile dyeing in Bamako, Mali. At two sites the effluents were emitted directly to the Niger River, at the third site the effluents were collected in a soakaway. The capacity of different materials, both coagulants and adsorbents, to treat the effluents was analysed with jar tests. pH, conductivity, total dissolved solids (TDS), turbidity and dissolved oxygen (DO) were analysed on samples before and after jar tests, and on river water from spilling site. For some jar tests, UV-Vis spectra and content of zinc, nickel and copper were analysed. Properties of dyestuffs were analysed with spectrophotometry, scanning electron microscopy (SEM) and nuclear magnetic resonance spectroscopy (NMR). Iron(III) chloride coagulated dye effluents, efficiently removing most of the colour from water. Activated carbon, both in granulated form and in the form of powder, showed some capacity to adsorb compounds in dye effluents. Rice chaff, rice bran, laterite, bentonite and aluminium sulfate did not show capacity to remove dyes from effluents. The composition of the dyestuffs used in small scale dyeing is not known, which is a serious problem when developing treatment methods. A significant fraction of the dyestuffs consists of substances which are not part of the colour-yielding dye. Five dyestuffs with different colours were analysed with SEM with X-ray fluorescence detector. These dyestuffs contained, except for carbon, oxygen and nitrogen which can not be detected, mainly sulfur, chloride, sodium and, in the case of green, barium. Traces of chromium, vanadium, iron, aluminium and silicon were also detected in some of the dyestuffs. Mixed effluents from two sampling sites contained concentrations of zinc and nickel higher than WHO guideline values for drinking water. Further studies are needed to find a cheap treatment method since low cost materials such as rice bran and laterite are ineffective. In addition to be able to remove polluting substances from dye effluents, the method should include cheap and readily accessible materials, and be supported by an infra-structure which allows the effluents to be treated locally. To find a working solution to decrease water pollution, without threatening the livelihood for dyers, co-operation between universities, dyers and governmental bodies is crucial. Le traitement des eaux usées est important au Mali, un pays largement sec où le fleuve Niger est récepteur de la majorié des effluents industriels et artisanals. Le fleuve est aussi une source d’eau potable et est important pour la pêche locale. L’histoire de teinture est longue en Afrique de l’Ouest, à l’époque effectuée avec des materiaux naturels, mais à parti des années 1950 de plus en plus avec des colorants synthétiques. Les tissus en cotton tissés avec la technique damas et colorés par des colorants synthétiques, appellés basins, sont importants dans la culture Malienne. Ils sont utilisés pour des vêtements portés pendant des cérémonies mais aussi dans la vie quotidienne. À Bamako, la teinture des textiles est effectuée principalement par des femmes dans un secteur informel avec des méthodes artisanales. L’objectif de ce travail était d’étudier la possibilité de traiter des effluents de teinture de textile artisanal à Bamako avec des materiaux locaux pas chers. Les échantillons des effluents ont été pris dans trois sites de teinture artisanal à Bamako. Les effluents étaient déversés en direct dans le fleuve Niger dans deux sites, tandis que dans le troisième site les effluents sont déversés dans un puisard. Ensuite, des échantillons de l’eau du fleuve aval et de l’eau du fleuve où les effluents sont déversés, ont été pris. Le pH, la conductivité, le TDS, la turbidité et l’oxygène dissous sont analysés pour les effluents brut et les échantillons de l’eau du fleuve. La capacité des differents materiaux de traiter les effluents a été analysé avec des jar tests. Les materiaux ajoutés étaient la bentonite, le charbon activé en poudre et comme granules, laterite en poudre, son de riz en poudre et balle de riz. Ensuite, des solutions de sulfate d’aluminium et de chlorure de fer(III) étaient utilisées. Le pH, la conductivité, le TDS, la turbidité et l’oxygène dissous sont analysées avant et après jar test. Pour quelques jar tests des spectres UV-Vis et le contenu des metaux zinc, nickel et cuivre sont analysés. Les propriétés des colorants sont analysées avec spectophotométrie, microscope électronique et résonance magnétique nucléaire. Le chlorure de fer(III) a coagulé les effluents de colorants, c’est à dire les particules polluantes ont formé des flocs et sont sédimentés, laissant l’eau séparée des polluants. Le pH était baissé de 13 jusqu’à 2. Le charbon activé, en poudre et granulé, a montré la capacité d’adsorber les molecules qui absorbent les radiations électromagnetiques dans l’interval UV et visible, de la solution d’effluent. Bentonite, laterite, son de riz, balle de riz et sulfate d’aluminium n’ont pas séparé les polluants de l’eau. Le développement d’une méthode de traitement est limité par le manque de données sur la composition chimique des colorants utilisés. Une fraction importante des colorants vendus est composée d’autres components que la substance qui donne la couleur. Les cinq colorants analysés (vert, jaune, rouge, bleu et violet) sont solubles dans l’eau distillée, 0,01 M acide nitrique et 0,01 M hydroxide de sodium, et avaient la même couleur dissous dans les trois solvants. L’analyse avec microscopie électronique et un detecteur de fluorescence des rayons X a montré que les colorants sont composés de soufre, chlore et sodium, outre de charbon, oxygène, hydrogène et azote qui ne sont pas détectés avec cette analyse. Pour le colorant vert, une concentration de barium relativement élevée a été détecté. Des traces de chrome, vanadium, fer, aluminium et cilisium ont aussi été détectées. La recherche pour trouver une méthode de traitement des eaux usées de la teinture artisanalle à Bamako doit continuer car ce travail n’a pas trouvé de solution. Le materiel utilisé devrait séparer les polluants de l’eau et ne pas être cher. Ensuite une infrastructure pour le traitement est necessaire. Une cooperation entre l’université, les teinturières et les autorités est importante pour trouver une solution qui diminue la pollution de l’eau sans menacer l’entretien des teinturières. SLU/Dept. of Soil and Environment 2009 H2 eng fre https://stud.epsilon.slu.se/594/ |
| spellingShingle | water treatment textile dyes artisanal Mali Larsson, Hanna Textile dyeing in Mali : possibilities for small scale effluent treatment |
| title | Textile dyeing in Mali : possibilities for small scale effluent treatment |
| title_full | Textile dyeing in Mali : possibilities for small scale effluent treatment |
| title_fullStr | Textile dyeing in Mali : possibilities for small scale effluent treatment |
| title_full_unstemmed | Textile dyeing in Mali : possibilities for small scale effluent treatment |
| title_short | Textile dyeing in Mali : possibilities for small scale effluent treatment |
| title_sort | textile dyeing in mali : possibilities for small scale effluent treatment |
| topic | water treatment textile dyes artisanal Mali |