Characterization and treatment of textile printing wastewaters

Textile printing is becoming an important wastewater source as the water-based materials replace the organic solvents. The wastewaters originating from this operation are often strong and may contain toxics, although their volume is quite low. In this study, a textile printing plant was evaluated to assess pollution characteristics and treatment alternatives. Rotation printing wastewaters were found to be relatively diluted compared with other printing wastewaters, having a COD of around 800 mg l⁻¹ and responded with a high efficiency to both chemical precipitation and biological treatment. On the other hand, tube and item printing wastewaters contained solvents as well as high COD and TKN. Chemical treatment and aeration used as a pretreatment resulted in over 90 % COD removal together with high degree of color and solvent removal. Biological treatment following pretreatment resulted in an effluent COD of 250-500 mg l⁻¹. Nitrogen removal in the pretreatment stage was also assessed using magnesium ammonium phosphate (MAP) precipitation and air stripping. Results of the study were evaluated considering alternative treatment schemes.