Avaliação do fingerprint espectroscópico de águas residuárias urbanas através de métodos quimiométricos

Abstract

In the characterization of urban wastewater, several parameters are determined through physicochemical methods, which are costly, laborious, and generate waste that must be properly treated and disposed. Spectroscopic techniques provide a fingerprint of the sample. Thus, ultraviolet and visible (UV-Vis) spectroscopy, coupled with chemometric methods, such as unsupervised tools: Principal Component Analysis (PCA) and Independent Component Analysis Analysis - ICA), were used in the evaluation of urban wastewater in the Campo Mourão - PR allowing the extraction of structural chemical information and to perform the analysis of the composition of these samples, without generation of residues, thus being in agreement with the green chemistry requirements. It was possible to show the absorption of organic matter in the region from 200 to 300 nm, whose concentration decreases with the treatment processes. The results obtained also show a signal at 313 nm attributed to the nitrate, which increases its concentration during the treatment due to the ammonia oxidation. The phosphate signal remains constant at the treatment stages. The results demonstrate a correlation between settleable solids and absorption at wavelength 245 nm. Achieved results provide the wastewater characterization in agreement with the green chemistry requirements. These results evidenced to obtain an innovative process in the evaluation of the treatment performed for urban wastewater and a possible substitute for the setteable solids evaluation.