Removal of Dyes from Wastewater of Artisanal Dyeing Plants by Adsorption in a Fixed Bed Column of Deactivated Lichens

Abstract

Aims: Pollution by wastewaters from various urban activities such as artisanal dyeing plants is a real problem for developing countries. The treatment of wastewater by the adsorption method is carried out by means of less expensive and available adsorbent media. Two techniques of the adsorption method are possible: adsorption in continuous mode (column adsorption) and adsorption in discontinuous mode (batch adsorption). The choice of the continuous adsorption technique is justified by its ability to process large volumes of solutions. In this study, dyes contained in wastewater from artisanal dyeing plants were removed by continuous adsorption in a fixed-bed column of deactivated lichen biomass (Parmotrema dilatatum).
 Study Design: Random design
 Place and Duration of Study: Laboratory of Thermodynamics and Environmental Physico-Chemistry (University Nangui Abrogoua, Ivory Coast) between May 2020 and October 2020.
 Methodology: Four (4) categories of wastewater were collected in artisanal cotton and leather dyeing plants through two municipalities of the city of Abidjan, economic capital of Ivory Coast. Two (2) wastewaters colored in blue from dyeing of cotton boubous and jeans and two (2) wastewaters colored in red from dyeing of leather jackets and bags. These wastewaters were treated through the fixed bed column of deactivated lichens. The column feed rate was set at 0, 07 L.min-1 and the adsorbent bed mass at 100 g.
 Results: The study showed that, regardless of the nature of the dyed object and regardless of the target dye, the amount of dye adsorbed was better with waters of higher initial concentration. Thus the best amount of adsorbed dye is 44.444 mg.g-1 and the best removal rate is 97.9%. These values are obtained with the red wastewater of bags (RWB) treatment which was the most concentrated wastewater.
 Conclusion: Good efficiency of deactivated lichen bed as adsorbent for the in situ removal of dyes from wastewater by continuous adsorption.