How to treat printing and dyeing wastewater, and which process is most commonly used now, please provide relevant reference materials.

Printing and dyeing wastewater is a kind of industrial wastewater which is difficult to treat because of its dark and changeable color. For the soluble dyes contained in printing and dyeing wastewater, the traditional decolorization method is difficult to meet the technical and economic requirements of treatment, so decolorizing printing and dyeing wastewater with water-soluble dyes has become a major problem in the field of environmental protection technology at home and abroad at this stage.

The general treatment items of printing and dyeing wastewater include water temperature, ph, chromaticity, organic matter, ammonia nitrogen, toxic substances and surfactants.

Commonly used methods include physical method, chemical method, biological method and comprehensive treatment method.

Common physical methods include grid and drying net, wastewater equalization and adjustment, air flotation, sedimentation, surfactant foam separation, filtration and ultrafiltration.

Chemical methods include neutralization, coagulation, oxidative decoloration, electrolytic treatment and adsorption treatment.

Biological methods mainly include: anaerobic biological treatment method, activated sludge method, biofilm method and so on.

The combined treatment process generally includes anaerobic and aerobic biological treatment combined process, adsorption-biodegradation treatment process, biochar process, membrane bioreactor, DAT-IAT process and so on.