The presence of sulfonamides (SAs) in water has received increasing attention due to the risk to ecosystems. The adsorption and photocatalysis performance for sulfamerazine (SMZ) of Bi₂O₃–TiO₂ supported on powdered activated carbon (Bi₂O₃–TiO₂/PAC) nanoparticles was evaluated. The amount of doped Bi₂O₃ not only influenced the photocatalytic performance but also impacted the adsorption capacity. The adsorption mass transfer mechanism of Bi₂O₃–TiO₂/PAC was elucidated and is further discussed in combination with the photocatalytic mechanism. It was indicated that Bi₂O₃–TiO₂/PAC(10%–700 °C) performed best, and the SMZ removal by the adsorption–photocatalysis of Bi₂O₃–TiO₂/PAC(10%–700 °C) reached 95.5%. Adsorption onto active sites was a major adsorption step, and external diffusion was assisted. Superoxide radical (^●O₂⁻) and hole (h⁺) were identified as the major reactive oxygen species (ROS) for SMZ removal. Benzene ring fracture, SO₂ extrusion and nitrogenated SMZ were proposed as the main pathways for photocatalysis. Meanwhile, alkaline conditions enhanced photocatalytic performance, while contrary effects were observed for adsorption. The adsorption–photocatalysis removal performance for SMZ in lake water was better than that for river water. It can be generalized for the potential application of photocatalysis coupling with adsorption to remove refractory antibiotics in water.

The overall goal of urban water supply is to ensure the water quality from source to tap. As the “last mile”, the building water supply system (BWSS) is the crucial part in ensuring tap water safety, and its deteriorating water quality has attracted increasing attention. In this work, we provide a comprehensive overview of the pollution, configuration, purification and regulation of BWSSs, with a focus on ensuring water quality safety. Periodic water usage in buildings is a unique feature that leads to intermittent water stagnation and reduced residual chlorine. Biological pollution has become a key focus of existing studies due to its acute effects on human health, compared to the chronic effects of chemical pollution. For new systems, water quality risks can be reduced at the source by optimizing pipe materials and reasonable layout. It is recommended to introduce secondary disinfection technologies, as they are important for ensuring biosecurity. Moreover, supervision and maintenance are the basis for long-term efficient operation of BWSSs. This review constructs a framework for controlling water quality deterioration based on the wholse process, which is instructive for the design, operation, maintenance and management of BWSSs, and provides relatively clear research directions for improving water quality.