A numerical method of analyzing the composition of colored wastewater from dyeing plant

Studies on the effectiveness of removing colored impurities from wastewater after dyeing process obtained from five dyeing plants located in the Lodz region in Poland were performed as well as a comparative spectrophotometric analysis of wastewater before and after treatment, in the visible range of absorption of 350–750 nm, attributed to dyes from different groups and with different structures of chromophoric systems. It was found that the method of calculating differences in the total areas under the curves of absorption from the range of 280–800 nm cannot determine precisely the effectiveness of color wastewater treatment. The method using a normalization procedure of the relevant spectra and the analysis of their partial differences proposed in this work allows to describe the efficiency of the process more precisely and indicates the class of synthetic dyes used in dyeing processes, giving the opportunity to the selection of appropriate procedures for their removal or disposal. By analysis of II-derivative of absorption bands, amount of colored components in the wastewater and the effects of physicochemical and biological treatment have been identified. This made it possible to determine the class of the colored impurities remaining in the wastewater.