Combination of chromatographic and spectroscopic characterization based on primitive ultraviolet absorbance detection to fulfill advanced monitoring of dissolved organic matter in municipal wastewater treatment plant

Abstract

Effective and affordable monitoring tool for dissolved organic matter (DOM) in municipal wastewater treatment plant (WWTP) is in great need. In this study, high-performance size exclusion chromatography (HPSEC) with ultraviolet absorbance (UVA) detection and ultraviolet (UV) spectrometry were complementarily combined for advanced characterization of DOM in a municipal WWTP. DOM in different process units were chromatographically characterized mainly by UVA at 210 nm (UVA210), 254 nm (UVA254), UVA ratio index (URI, UVA210/UVA254). Differential and derivative UV spectrometry were also used for DOM characterization. HPSEC URI chromatographic analyses helped to acquire rich chemical information of DOM components with primitive UVA detection. Influent HPSEC fractions Ⅰ, Ⅳ, Ⅴ− 2, which were proved to consist of protein and polysaccharides, low molecular weight organic acids and hydrophobic organics respectively, were readily removable. HPSEC fractions Ⅱ and Ⅲ were proved to contain mostly recalcitrant humic substances (HS). Effluent HPSEC fraction Ⅴ− 1 contained nonbiodegradable saturated organics. UV spectrometry complemented HPSEC characterization by revealing that saturated organics generated during sand filtration and second derivative peak height at 295 nm (SDPH295) could be surrogate for biodegradable organics concentration in influent. Measures for DOM control optimization of this WWTP were proposed based on the DOM characteristics revealed. This study proved practicability of achieving advanced DOM monitoring with cheap and convenient but primitive chromatographic and spectroscopic characterization with UVA detection which may provide basis for developing applicable equipment for organic pollutants monitoring of municipal WWTP.