Performance evaluation of a moving bed biofilm reactor for hospital wastewater treatment: removal efficiency, seasonal variability, and risk assessment

Hospital wastewater poses significant environmental and public health risks due to pathogenic microorganisms, pharmaceutical residues, and heavy metals. A 1-year temporal analysis of the hospital wastewater treatment system was conducted, involving a systematic evaluation of seasonal and monthly variations of above pollutants. The chemical oxygen demand (COD) concentration at the hospital wastewater treatment plant (HWTP) outlet peaked at 85 mg/L in summer. The suspended solids (SS) concentration exhibited an increasing trend over time, reaching a maximum of 38.3 mg/L at the end of the year. The highest concentration of fecal coliforms (FCs) (3.2 × 10 3 MPN/L) appeared in May 2024. The moving bed biofilm reactor (MBBR) process demonstrates good performance in removing pollutants, such as ammonia nitrogen (NH 3 -N), COD, SS, FCs for hospital wastewater. The average removal rates of above pollutants reached 99.9%, 79.0%, 82.6%, and 71.5% respectively. Moreover, this study further investigates the emission patterns of fugitive gases (H 2 S, NH 3 , Cl 2 ) from different azimuths around the HWTP. The concentrations of the six heavy metals in the effluent of the HWTP were all lower than the discharge standards. Both the single-factor pollution index (P i ) and the Nemerow pollution index (P N ) were less than 0.1, indicating a low risk of heavy metal pollution. It provides a theoretical basis and practical guidance for the regulation of hospital wastewater and the optimization of operational parameters for treatment processes.