Abstract:Antibiotic resistance pollution has become a major threat to public health and ecological security, and wastewater treatment plants (WWTPs) are widely recognized as important reservoirs and emission sources of antibiotic resistance genes (ARGs). To quantify the environmental dissemination risk of wastewater-borne resistomes, we integrated and reanalyzed 81 metagenomic samples from 29 WWTPs in 11 countries, including influent, effluent, and paired upstream and downstream receiving river samples. These publicly available datasets span approximately the last decade and cover eight representative biological treatment configurations. In total, 1,794 ARG subtypes affiliated with 27 ARG types were detected. Influent samples exhibited significantly higher ARG abundance (mean: 2.16 copies/cell) and diversity (mean: 556 subtypes) than effluent and river samples. Even after full-scale wastewater treatment, the effluent still retained a mean abundance of 0.65 copies/cell and a mean of 295 ARG subtypes, indicating incomplete elimination of wastewater-derived resistomes. Relative to upstream river water, downstream sites showed mean increases of 39.5% in ARG abundance and 11.3% in ARG diversity. To move beyond descriptive resistome profiling, we applied a structured, comprehensive risk assessment framework based on MetaCompare (v2.0). This framework integrates three dimensions of ARG-related risk, namely, occurrence features, mobility potential, and host pathogenicity. The results showed that the overall resistome risk score of downstream receiving waters increased by an average of 35%, indicating that wastewater discharge elevates ARG loads and amplifies their potential ecological and health relevance. Building on this risk-oriented analysis, we identified 23 wastewater-derived ARGs posing a risk according to their occurrence, persistence, and downstream proliferation characteristics. Collectively, these high-risk subtypes accounted for 22.6% of the total ARG abundance in downstream waters. Among them, qacH, mexW, and oqxB displayed particularly strong environmental proliferation potential, whereas APH(6)-Id, aadA, sul1, and sul2 warrant special concern because they have also been classified as clinically important high-risk ARGs. Marked differences were observed among treatment processes. Anaerobic-anoxic-oxic (AAO), oxidation ditch (OD), and sequencing batch reactor (SBR) processes removed more than 80% of the wastewater-derived ARGs with dissemination risk, whereas cyclic activated sludge system (CASS) and membrane bioreactor (MBR) processes showed selective enrichment effects for several subtypes. A plausible explanation is that the fluctuating redox and substrate conditions in the CASS, together with the high biomass density, prolonged sludge retention time, biofilm- or membrane-associated microbial aggregation, and residual extracellular DNA in the MBR, may create favorable niches for the persistence, horizontal transfer, or selective enrichment of certain ARGs. Overall, the environmental dissemination risk framework established here, the identification of representative wastewater-derived high-risk ARGs, and the process-specific removal spectrum provide a useful scientific basis for mechanistic studies and for the development of more targeted mitigation strategies against antibiotic resistance pollution. Close-