Recently, Associate Professor Xu Hangzhou from the School of Environmental Science and Engineering at Shandong University has made new progress in the study of high-odor water driven by cyanobacterial blooms treated with advanced oxidation processes (AOPs). The related research, entitled “Investigation of nitro(so)- and chloro-disinfection byproduct formation mechanisms after UV/Cl₂ and UV/H₂O₂ oxidation of 2-methylisoborneol in the presence of algal organic matter”, was published in the top international environmental journal Water Research (2025, 124616). Master’s student Li Sihong is the first author of the paper, with Associate Professor Xu Hangzhou as the corresponding author. Shandong University is listed as both the first completing institution and the independent corresponding author institution.

Global climate change and the intensification of water eutrophication have led to frequent cyanobacterial blooms, releasing odorous compounds such as 2-methylisoborneol (2-MIB), which pose a serious threat to drinking water safety. Dominant algal species, represented by Pseudanabaena, are the main sources of 2-MIB. Even after conventional coagulation and filtration, a substantial amount of extracellular 2-MIB remains difficult to remove. To address the high-odor problem caused by cyanobacterial blooms in water sources, this study compared the effectiveness of two commonly used UV-based AOPs (UV/Cl₂ and UV/H₂O₂) in removing odor compounds. It also analyzed the differences in toxicity and disinfection byproducts (DBPs) in the treated water, and employed FT-ICR MS combined with machine learning to investigate the precursor characteristics of chloro-DBPs (Cl-DBPs) and nitro(so)-DBPs.

The results showed that UV/H₂O₂ achieved a higher 2-MIB removal efficiency (98.1%) compared with UV/Cl₂ (85.6%), while also exhibiting lower post-chlorination toxicity. In contrast, UV/Cl₂ treatment led to a significant increase in post-chlorination toxicity, primarily due to the formation of highly toxic nitro(so)-DBPs. FT-ICR MS coupled with machine learning revealed that, compared with Cl-DBP precursors, nitro(so)-DBP precursors are typically non-aromatic compounds with higher H/C ratios and lower oxidation degrees. The findings provide important guidance for the targeted removal of DBP precursors following advanced oxidation.

This study focused on the removal of 2-MIB released from cyanobacterial blooms and compared the performance of UV/H₂O₂ and UV/Cl₂ AOPs in the presence of algal-derived organic matter. UV/H₂O₂ exhibited superior 2-MIB degradation and lower post-chlorination toxicity, while UV/Cl₂ tended to generate more toxic nitro(so)-DBPs, increasing the overall water risk. By integrating FT-ICR MS with machine learning, the work clarified the distinct precursor characteristics and formation pathways of different DBP classes. This is the first study to incorporate nitro (so)-DBPs into the AOM-derived DBP evolution framework, providing both theoretical support and practical guidance for optimizing drinking water treatment processes.

This research was supported by the National Natural Science Foundation of China, the Natural Science Foundation of Shandong Province, and the Youth Innovation Team Project of Higher School in Shandong Province.