Abstract: The characteristics of dyeing and printing wastewater include large water volume,significant fluctuation of water quality,high content of organic pollutants,deep color,and large pH fluctuations,which makes it one of the most difficult industrial wastewater to treat.Currently,the main methods for treating such wastewater are biological treatment,membrane separation,and chemical oxidation.However,these methods are often limited by poor biodegradability,high cost,and ineffective color removal.This experiment aimed to treat dyeing and printing wastewater discharged from a large dyeing and printing company by culturing and acclimating microorganisms.A combined process consisting of anaerobic,aerobic,and flocculation steps was used to degrade PVA-type pollutants in the wastewater.Throughout the process,the water quality of each treatment unit was continuously monitored to evaluate the biodegradability(BOD₅/COD ratio)of the dyeing wastewater and to determine the optimal process route.This provides a technical basis and reference for the promotion and application of the technology in industrial settings.

Key words: printing and dyeing wastewater, biodegradability, anaerobic-aerobic process with flocculation, process route