Table 1: The characteristics of the investigated dye effluents.

Effluent from dyeing process of Dyeing technology Abbreviation in text Azo dyes in effluents Other substances in effluents pH COD (mg ) Max of absorbance () in raw effluents Comments C.I. name Chemical character Polyacrylic fibres Continuous process WPac Basic Yellow 28 Basic Red 22 Basic Blue 41 Basic Black Cationic Cationic Cationic Cationic Thickener (Prisulon), Auxiliary agents (Roksol PAN 3K), Glutaric acids 4.4 ± 0.1 1440 0.262 (340 nm) 0.159 (430 nm) 0.166 (540 nm) 0.199 (610 nm) Biologically stablea       Acid Red 88 Anionic           Leather Batch process WLeat Acid Blue 193 Anionic <10% of tannery wastes 7.0 ± 0.1 460 0.365 (510 nm) 0.075 (620 nm) Biologically unstablec       Other dyesb Anionic           Flax fabric Batch process WFlax Unknown Anionic Unknown 6.9 ± 0.1 910 0.965 (350 nm)d Biologically stablea Cotton fabric Batch process WCot Direct Black 22 Anionic Unknown 8.2 ± 0.2 8930 40.05 (480 nm) Biologically stablea

aThe biological stability of dyeing effluent was estimated based on changes in their appearance (changes in UV-VIS spectrum, precipitation of sediments) and their digestion during the storage period of 28 days (at 20°C under anaerobic conditions). bOnly in trace amounts. cEffluents were digested during short-time storage (about few hours) but their absorbance at 510 nm did not undergo significant changes. dAbsorption band without any clear maximum.