FEASIBILITY OF EFFICIENT COD REMOVAL OF SIMULATED DOMESTIC SEWAGE FROM INLAND SHIPS IN SINGLE-STAGE CSTR UNDER MICROAEROBIC CONDITION

To improve domestic sewage treatment technology applied on inland ships, the feasibility of using a simplified single-stage continuous stirred tank reactor (CSTR) under microaerobic conditions was assessed in this study.With an optimized hydraulic retention time of 24 hours, the oxidation-reduction potential of the system fluctuated between -329 and -171 mV, confirming stable microaerobic conditions.The minimum effluent chemical oxygen demand (COD) reached 39 mg/L, corresponding to a maximum degradation efficiency of 96.9% on day 106, while the highest total nitrogen (TN) removal was 77.1%.Analysis of microbial diversity showed higher abundance and metabolic activity in the intermediate and late stages, with dominant microflora shifting from Betaproteobacteriales (53.0%) and Flavobacteriales (22.9%) to Saccharimonadales (average 76.6%) at the order level.These microbial community dynamics were closely associated with pollutant removal efficiency, highlighting the adaptability of functional microorganisms under microaerobic conditions.This study validated the feasibility of effectively treating high-concentration simulated ship sewage using a single-stage CSTR without continuous aeration.The results emphasize the advantages of a compact, low-energy, and high-efficiency treatment process suitable for small and medium-sized inland vessels.Beyond meeting discharge standards, this approach offers potential for sustainable onboard wastewater management and provides a scientific basis for future development and scaling of practical treatment technologies in inland waterway transport.