Drinking water safety is closely related to the national economy and people's livelihood, and disinfection plays a controlling role in ensuring the sanitation and safety of drinking water. However, due to the complexity of water treatment and disinfection reactions, disinfectants inevitably react with organic matter in water to produce strong "three- 致" toxic disinfection by-products (DBPs), posing a serious threat to water quality safety. Large urban water supply systems are characterized by large scale, long pipeline networks, and high sanitary requirements, making it particularly important to ensure disinfection effectiveness and control DBPs. This project, funded by more than 20 projects including the National Water Special Project and the 863 Plan, has been continuously researched and developed for over a decade, achieving the following innovative results: 1) Overcoming the key technologies for identifying and detecting various types of pathogenic microorganisms and DBPs in drinking water. Solved the difficult problem of water quality safety risk analysis in urban water treatment plant disinfection processes. Constructed a real-time quantitative q-PCR analysis detection technology system to achieve high-throughput identification and quantification of conditional pathogens; developed 50 DBPs analysis detection technologies and new precursor recognition methods for drinking water, with detection limits reaching ng/L level, improving accuracy by 15%-35% compared to traditional methods. 2) Developed integrated key technologies suitable for safe disinfection of large urban water treatment plants, providing comprehensive technical solutions for efficient operation of drinking water disinfection processes. Developed a sequential combination disinfection technology that converts free chlorine into monochloramine, achieving over 90% monochloramine content in total residual chlorine at the factory outlet, saving 15%-20% on water treatment plant disinfectants; optimized existing disinfection methods in water treatment plants to achieve synergistic control of pathogenic microorganisms and DBPs; Innovated the implementation of multi-level barrier precursor efficient reduction deep treatment technology, which reduces the potential for DBPs generation in plant effluent by more than 50% compared to conventional processes; developed a new set of proprietary electrolytic sodium hypochlorite production technology, equipment, and application systems that can completely replace liquid chlorine in water plants, suitable for different scale water plants. 3) Innovated the implementation of comprehensive control technologies for low-dose residual chlorine maintenance in pipelines based on multi-level chlorination and bio-nitrification on pipe walls. While ensuring the biological safety of the water supply system, the odor of chlorine has been significantly improved, with an annual increase in pipeline odor pass rate, and a reduction in complaints about odors from residents by more than 60%; invented various new disinfection methods such as pressure CO2 disinfection, UV/chlorine combination, nano-iron/zero-valent iron reduction, and DBPs control technologies, providing a series of technical solutions for decentralized terminal control of pathogenic microorganisms and DBPs. 4) A systematic design method for the clear water tank of a waterworks based on hydraulic and disinfection performance CFD simulation has been developed; China's first local standard for drinking water, Shanghai's 'Standard for Drinking Water Quality' (DB31/T1091-2018), was researched and formulated, with disinfection-related indicators superior to the current national standards for water quality, fully aligning with international advanced water quality standards; Drinking water safety disinfection technology and key parameters have been proposed, effectively supporting the revision of the latest National 'Outdoor Water Supply Design Standard' (GB50013-2019). The project has obtained 20 invention patents and 10 utility model patents; published 132 papers, including 71 SCI papers (average impact factor 4.955), 5 ESI papers, with 1787 citations; published 4 monographs; formulated 1 Shanghai local standard. Participated in the compilation of 1 national standard. The results were applied to 23 water plant projects in China (total capacity of 9.3079 million tons per day), serving a population of 45 million, with an additional three-year output value of 3.025 billion yuan, saving 16,500 tons of disinfectants, and an equipment sales revenue increase of 72.12 million yuan over three years, generating foreign exchange earnings of 2.14 million US dollars. This has promoted the development of drinking water disinfection processes and DBPs control technology in China, effectively safeguarding residents' drinking water health, and creating significant social, economic, and environmental benefits.