Integrated Physicochemical Characterization and Amplicon-Based Microbial Profiling of Dental Unit Wastewater

Dental unit wastewater (DUW) from routine dental activities may contain harmful chemical constituents, trace metals, and microorganisms. This study analyzed the physicochemical properties and microbial communities of DUW collected from restorative (SW1) and surgical (SW2) units at Bangkokthonburi University in September 2024. We measured parameters such as pH, electrical conductivity (EC), turbidity, total suspended solids (TSS), total dissolved solids (TDS), dissolved oxygen (DO), biochemical oxygen demand (BOD), nutrients, and trace metals using standard methods and ICP-OES. For microbial profiling, we used Illumina MiSeq sequencing to target the bacterial 16S rRNA and fungal ITS1 regions, and analyzed the data with the QIIME2 pipeline. The samples exhibited pH values from 6.40 to 6.56 and EC values between 0.236 and 0.257 mS/cm. Moderate turbidity, TSS, and TDS levels were observed. Dissolved oxygen ranged from 13.1 to 15.8 mg/L, and BOD was low at 3 to 4 mg/L, indicating limited biodegradable organic load. Trace metals detected included zinc, copper, iron, magnesium, and arsenic, while lead, chromium, cadmium, and mercury were not found. The microbial communities were dominated by Proteobacteria, Firmicutes, Actinobacteriota, and Bacteroidota among bacteria, and Ascomycota and Basidiomycota among fungi. These results provide important baseline data for managing dental wastewater systems.