Pollutant footprint analysis for wastewater management in textile dye houses processing different fabrics

BACKGROUND: This study investigated the water and pollution footprints of a dye house, which processed cotton knits, polyester (PES) knits and PES-viscose woven fabrics. Experimental evaluation was carried out for each processing sequence. Variations in wastewater flow and quality were established as a function of the production program in the plant. A model evaluation of wastewater dynamics was performed and defined specifications of an appropriate treatment scheme. RESULTS: The plant was operated with a capacity of 4300 t year ⁻¹ of fabric, which generated a wastewater flow of 403 500 m ³  year ⁻¹ and a COD load of 675 t year ⁻¹ . The overall wastewater footprint of the plant was computed as 91 m ³  t ⁻¹ and the COD footprint as 160 kg t ⁻¹ of fabric. Depending on the fabric type, results indicated expected changes in wastewater flow between 600 and 1750 m ³  day ⁻¹ ; in COD load between 1470 and 2260 kg day ⁻¹ and in COD concentration between 1290 and 3400 mg L ⁻¹ . CONCLUSION: A model simulation structured upon COD fractionation and related process kinetics revealed partial removal of slowly biodegradable COD, coupled with high residual COD, which would by-pass treatment. Resulting biodegradation characteristics necessitated an extended aeration system, which could also enable partial breakdown of residual COD. Effluent COD could be reduced to 220–320 mg L ⁻¹ with this wastewater management strategy.