Deciphering molecular composition and summarizing control strategies of unknown disinfection by-products in water and wastewater based on FT-ICR-MS analysis: a comprehensive review

Disinfection is crucial to inactivate pathogenic bacteria and prevent the spread of epidemic diseases during drinking water/wastewater treatment. However, adverse disinfection by-products (DBPs) are inevitably produced during the disinfection process. Previous reviews primarily paid attention to the occurrence, formation, and control of some known DBPs, whereas few studies focused on the relatively large proportion of unknown DBPs. This study provided an overall review of unknown DBPs in different water bodies. Firstly, the analytical method of unknown DBPs based on Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) analysis was described in detail. Secondly, the molecular composition and characteristics of unknown DBPs in various water bodies during different disinfection processes were systemically summarized. Moreover, the possible transformation reactions involved in forming unknown DBPs were thoroughly proposed. Thirdly, the control strategies (e.g., pre-treatment, selection and optimization disinfection conditions, and post-treatment) of unknown DBPs were comprehensively listed. Finally, future studies should focus on identifying molecular structures, screening the highly toxic compounds, investigating the formation mechanisms, and developing more effective control strategies for unknown DBPs. Overall, this review will narrow the knowledge gap about the composition and control of unknown DBPs in different water bodies, thereby protecting human health and improving ecological safety.