Evaluation of a Low-Cost Active Air Sampler for the Surveillance of Airborne Transmission of Antibiotic Resistance Genes Using a Municipal Wastewater Treatment Plant as a Case Study

Assessing the risks associated with antibiotic resistance genes (ARGs) in the environment remains challenging due to limited understanding of their distribution and transmission across various media, including wastewater, air, and biosolids. This study addresses this gap by systematically collecting samples from diverse environmental sources and investigating the dynamics of ARG transmission in wastewater treatment plants (WWTPs). A low-cost 3D-printed air sampler was developed using off-the-shelf components and evaluated alongside a commercial active air sampler under identical conditions. The custom sampler was equipped with interchangeable filters, including glass fiber and PVDF membranes, and showed comparable or better performance in terms of ARG detection. While only single 24-h sampling events were conducted per sampler, differences in ARG yield, microbial diversity, and assembly metrics were observed. Using metagenomic sequencing, air samples from locations near effluent discharge points and within biosolids processing areas, alongside wastewater samples, were analyzed. Genomic predictions and homology analyses revealed that ARGs are widely distributed across environmental media, with significant overlap between air and water samples. ARG abundance was higher in the biosolids processing area than at the effluent discharge point. This study introduces a cost-effective monitoring tool for airborne ARGs and provides novel insights into their environmental distribution and potential transmission in WWTPs, informing future risk assessment strategies.