Occurrence characteristics, removal efficiencies and potential health risks of typical viruses in rural domestic sewage: A review

Dissimilar sources, treatment processes, resource-oriented models, lack of disinfection, and proximity to living areas may contribute to distinct virus occurrence, removal efficiencies, and risks in rural compared to urban sewage. This study reviews research on viruses in rural domestic sewage from 2000 to 2024, comparing virus removal efficiencies of common rural treatment processes and identifying potential health risks. It finds that typical virus species in rural sewage resemble those in urban areas but at lower concentrations, with a higher prevalence of animal and plant viruses. The concentrations of typical virus range from 102 to 108 GC/L in influent and 100 to 106 GC/L in effluent. Among existing treatment processes, ecological treatment is more effective in virus removal (0.6 log10 to complete removal), whereas contact oxidation, commonly used in rural settings, has relatively low efficacy (0.2-3.0 log10). Effluent discharge (101-1010 GC/L), excess sludge utilization (102-1010 GC/(g wet wt.)), and fugitive gas (103-107 GC/m3) from treatment processes heighten potential risks of virus exposure. This study conducts a comprehensive analysis of existing research, enhancing understanding of the potential risks and research significance of viruses in rural domestic sewage. It underscores the importance of developing virus research and control strategies under current context and proposes several future research directions in conjunction with existing analyses, including migration pathways, detailed removal mechanism, control technologies, and comprehensive risk assessment of viruses in rural sewage.