Removal of fluorescence and ultraviolet absorbance of dissolved organic matter in reclaimed water by solar light

Storing reclaimed water in lakes is a widely used method of accommodating changes in the consumption of reclaimed water during wastewater reclamation and reuse. Solar light serves as an important function in degrading pollutants during storage, and its effect on dissolved organic matter (DOM) was investigated in this study. Solar light significantly decreased the UV₂₅₄ absorbance and fluorescence (FLU) intensity of reclaimed water. However, its effect on the dissolved organic carbon (DOC) value of reclaimed water was very limited. The decrease in the UV₂₅₄ absorbance intensity and FLU excitation–emission matrix regional integration volume (FLU volume) of reclaimed water during solar light irradiation was fit with pseudo-first order reaction kinetics. The decrease of UV₂₅₄ absorbance was much slower than that of the FLU volume. Ultraviolet light in solar light had a key role in decreasing the UV₂₅₄ absorbance and FLU intensity during solar light irradiation. The light fluence-based removal kinetic constants of the UV₂₅₄ and FLU intensity were independent of light intensity. The peaks of the UV₂₅₄ absorbance and FLU intensity with an apparent molecular weight (AMW) of 100 Da to 2000 Da decreased after solar irradiation, whereas the DOC value of the major peaks did not significantly change.