Reassessing systemic blind spots in modern water disinfection paradigms

Disinfection plays a crucial role in ensuring healthcare and the safety of drinking water and sewage reuse. However, our current understanding of the factors influencing disinfection remains incomplete. This review offers a comprehensive examination of the often-neglected aspects in disinfection, such as micro- and nanoplastics (MNPs), bacterial states, quorum sensing, and horizontal gene transfer. A meta-analysis was conducted to evaluate the exposure risk and impacts associated with MNPs in water disinfection systems. Our findings indicate that within a specific concentration range of 5 μg·L⁻¹ to 11.43 g·L⁻¹, higher concentrations of MNPs hinder the bacterial inactivation rate and significantly increase the frequency of horizontal gene transfer following disinfection. Furthermore, MNPs also promote the formation of disinfection by-products (DBPs), with larger size of MNPs having a stronger effect. Among the various types of MNPs, studies predominantly focus on the response of polyethylene, and polyethylene terephthalate caused distinct promotion of DBPs. Our review also highlights existing knowledge gaps and challenges in the disinfection processes and facilitates the assessment of the risk of these influence factors, thereby supporting the development of advanced disinfection technologies. Additionally, it suggests prospective research directions in the field of water disinfection, aiming at improving disinfection processes.