Removal of Indigo Dye in Denim Plant Wastewater by CO2-Capturing Macroalgae

Macroalgae

The indigo used in dyeing jeans is difficult to remove from the wastewater due to the recalcitrant nature of the dye. Therefore, denim dye wastewater treatment is considered key to maintaining the sustainability of the textile industry. This project demonstrates a biological post-treatment method to remove indigo blue in wastewater from denim factories by using sunlight and macroalgae species. The dye in the wastewater is broken down by the enzymes produced in the metabolism of the macroalgae species such as Cladophora and Chaetomorpha for dye biodegradation. This biological dye removal system also helps consume the carbon dioxide waste gas emitted from the denim factory, leading to a more active process of capturing carbon dioxide and contributing to a cost-effective, energy-efficient and eco-friendly solution for the reduction of wastewater dye pollutants from denim factories.


Application

Using a bio-degradable mechanism to remove the indigo dye. Enzymes are produced in the metabolism of macroalgae. During biodegradation, indigo dye breakdowns to isatin and then simpler compounds via enzymatic conversion by algae. Once the chemical structure of indigo dye is broken down, no further decolourisation is needed.
Industry Benefit

This algae-based wastewater decolouring system can be added to denim factory equipment operation system. It decolourises the denim wastewater and absorb CO2 using macroalgae. It can also make use of sunlight for power supply with PV panels installed and for supporting the growth of macroalgae. The whole system intends to use natural resources that contributes to a sustainable denim manufacturing. 
Technological Breakthrough
  • Application of algae species for mitigating indigo denim plant wastewater is proposed
  • A water treatment setup with light collecting and transmitting devices
  • A pure biological decolourisation treatment to indigo dye; low infrastructure cost compared to conventional treatment
Awards
Special Edition 2022 Inventions Geneva Evaluation Days - Silver Award
Project Name (ITF)
Removal of Indigo Blue Color in Denim Plant Wastewater by Macroalgae – A Preliminary Study
Project Number (ITF)
ITP/012/21TP