Regulating colored textile wastewater by 3/31 wavelength ADMI methods in Taiwan

Area of Science:

• Environmental Science
• Chemical Engineering
• Water Treatment Technology

Background:

• Textile dyeing wastewater presents significant treatment challenges due to high color intensity and variable composition.
• Taiwan implemented an Effluent True Color Standard (400 ADMI units) in 1998, necessitating effective color removal technologies.
• The industry faces challenges in meeting regulations with existing wastewater treatment systems.

Purpose of the Study:

• To assess the effectiveness of current wastewater treatment systems in textile dyeing facilities.
• To evaluate the correlation and interchangeability between the 3-wavelength (WL) and 31-WL American Dye Manufactures Institute (ADMI) color measurement methods.
• To identify challenges faced by the Taiwanese textile industry in complying with effluent color standards.

Main Methods:

• Selected ten representative textile wastewater treatment facilities for a 10-day sampling period.
• Analyzed effluent using both 3-WL and 31-WL ADMI Tristimulus Filter Methods.
• Evaluated the efficacy of biological and chemical coagulation treatment processes.

Main Results:

• A significant difference was observed between the 3-WL and 31-WL ADMI methods, indicating they are not interchangeable.
• Commonly employed treatment technologies (biological + chemical coagulation) were found to be ineffective in removing dye.
• Sodium hypochlorite (NaOCl) was frequently used as a post-treatment step to meet discharge limits.

Conclusions:

• The 3-WL and 31-WL ADMI methods require distinct discharge standards due to significant measurement differences.
• Current wastewater treatment technologies are inadequate for effectively decolorizing textile dyeing effluents.
• Additional or alternative treatment strategies are necessary for sustainable compliance with color discharge regulations.