Garment wastewater primarily originates from wet processes during production, including washing, dyeing, printing, and finishing. According to authoritative publicly available data, its specific sources can be summarized as follows:
1. Dyeing and Printing Processes: Including dyeing, printing, and color fixing, this is the most significant source of wastewater, accounting for approximately 70-80% of the total wastewater. This wastewater contains large amounts of dyes, auxiliaries, sizing agents (such as PVA), and surfactants, characterized by high color intensity, high COD (Chemical Oxygen Demand), and recalcitrant organic matter.
2. Washing and Finishing: Processes such as washing, softening, and desizing of denim garments generate wastewater containing detergents, pumice powder, and dye residues.
3. Fabric Pretreatment: Including desizing, scouring, bleaching, and degreasing, this discharges wastewater containing alkalis, bleaching agents (such as sodium hypochlorite), grease, and natural impurities.
4. Equipment and Site Cleaning: Wastewater generated after production by cleaning equipment, floors, pipes, etc., containing suspended solids, fibers, and chemical residues.
5. Cleaning of auxiliary materials: Cleaning of metal parts such as zippers and buttons before processing or installation, as they may contain heavy metal ions or oil stains.
