Recent Advances in Hospital Wastewater Treatment Technologies for Controlling Antibiotic Resistance: A Systematic Review

Introduction: Hospital wastewater is a key source of antibiotic-resistant bacteria and genes, driving the spread of environmental antimicrobial resistance (AMR). This review assessed the effectiveness of advanced treatment technologies in removing these resistance determinants from wastewater. Materials and Methods: This study adhered to the PRISMA guidelines and the PECOS framework. A comprehensive systematic search of six major databases (PubMed, Scopus, Web of Science, Google Scholar, ProQuest, and ScienceDirect) was conducted between April and June 2025. Of the 412 records initially identified, 89 studies met the predefined inclusion criteria. Relevant data on treatment technologies, antibiotic-resistant bacteria (ARB), resistance gene (ARG), and geographical–economic contexts were extracted and synthesized qualitatively. Results: Conventional treatment methods (e.g., activated sludge and chlorination) fail to fully remove ARB/ARGs and may even promote horizontal gene transfer via oxidative stress. In contrast, advanced technologies, such as MBR, advanced oxidation process (AOPs), and hybrid systems (MBR+ozone, MBR+GAC), achieve much higher removal efficiencies (>95%). Numerous critical ARGs (blaNDM, blaCTX-M, sul1, tetM, mcr-1, and vanA) have been detected in major pathogens (E. coli, P. aeruginosa, and Enterococcus spp.) in hospital wastewater worldwide. Research is largely focused on China, India, and Europe, while neglecting sludge and biofilms as important secondary reservoirs of ARGs, limiting accurate risk assessment. Conclusion: Effective AMR control in hospital wastewater requires integrated treatment technologies, molecular monitoring, and a One Health approach. Smart, sustainable solutions are essential to reduce risks to public health and ecosystems.