Monitoring WWTP performance using size-exclusion chromatography with simultaneous UV and fluorescence detection to track recalcitrant wastewater fractions

A trial monitoring of a typical full-scale municipal WWTP in Central Finland was aimed to explore applicability of high performance liquid chromatography - size exclusion chromatography (HPSEC) with simultaneous UV and fluorescence detection as a tool for advanced routine monitoring of wastewater treatment. High, intermediate, and low molecular weight (MW) fractions of untreated wastewater (influent) and treated wastewater (secondary effluent) were characterized in terms of UV absorbance at 254 nm (UVA(254)) and specific fluorescence representing tyrosine-like, tryptophan-like, and humic/fulvic-like compounds. The activated sludge treatment removed 97 +/- 1% of BOD, 93 +/- 2% of COD, 71 +/- 7% of DOC, and 24 +/- 7% of TN, while the overall reduction of UVA(254) was 50 +/- 6%. Total fluorescence signal declined by similar to 80% for tyrosine-like, by 60-70% for tryptophan-like, and by 7-36% for humic/fulvic-like compounds. Low and intermediate MW humic/fulvic-like compounds fluorescing at lambda(ex)/lambda(em) = 390/500 nm demonstrated recalcitrant behavior. Protein-like and humic/fulvic-like fractions of low MW <1 kDa accounted for 60-65% of total UVA(254) and 50-70% of total fluorescence of whole influent and effluent samples. Strong linear correlations were observed between wastewater BOD, COD, DOC, UVA(254) and tyrosine-like, tryptophan-like fluorescence. (C) 2018 Elsevier Ltd. All rights reserved.