Study on the removal of humic acid by ultraviolet/persulfate advanced oxidation technology

Abstract

Humic acid (HA) in water is the main precursor of disinfection by-products in the chlorination process of drinking water. In this study, an ultraviolet/persulfate (UV/PS) process, in a laboratory-scale system, is successful in the degradation of HA. The results showed that HA was significantly degraded (UV 254 removal rate of~89%) and partially mineralized (6 2.5%) by UV/PS treatment at a PS dose of 0.4 mM, pH of 7.12, and UV irradiation time of 160 min. The trihalomethane formation potential (THMFP) was also significantly reduced (THMFP reduction of~85.4%). A strong linear relationship was observed between UV 254 and dissolved organic carbon. The removal rate of HA at low pH was better than that at high pH conditions, and the inhibition by Cl − slowed down after an initial increase, and the inhibition was weaker than HCO 3 − . By analyzing the fluorescence spectrum of two humic-like substances, the fluorescent compounds C1 and C2 in HA were significantly degraded, and the change in C1 and C2 concentration was correlated with the decrease of THMFP. The degradation of different fractions of natural organic matter in real-world water samples indicated that UV/PS has significant potential to decrease HA in water.

Rapid Oxidation of Ammonia Nitrogen to Nitrogen Gas by UV-Activated Persulfate with Calcium Oxide

“…As can be seen in Figure c, the removal of NH 4 + -N increased from 50.0% to 100% as the PS dosages increased from 0.6 to 2.4 g/L. Increasing PS dosage increased the utilization of UV photons and promoted the generation of more ROS, − which was beneficial for NH 4 + -N oxidation. The variations of PS in UV/PS/CaO and PS/CaO were compared in Figure S10.…”