This study aimed to evaluate the treatment performance of a compact integrated Anoxic–Aerotank–Membrane Bioreactor (MBR) system designed for decentralized domestic wastewater treatment in a university campus environment. The experimental system was installed at Thu Dau Mot University (Vietnam) with a design capacity of 1.0 m³/day to investigate the effectiveness of combining biological treatment processes with membrane filtration under practical operating conditions. The treatment configuration consisted of an equalization tank, an anoxic reactor, an aerobic Moving Bed Biofilm Reactor (MBBR), and a submerged membrane bioreactor followed by a disinfection unit. Wastewater samples were collected at different treatment stages over a 50-day operational period. Key water quality parameters including BOD₅, COD, TSS, NH₄⁺–N, total phosphorus (TP), and coliforms were analyzed to assess system performance and stage-based pollutant removal. The results demonstrated high treatment efficiencies, with overall removal rates reaching 96.2% for BOD₅ and COD, 99.5% for TSS, 92.5% for NH₄⁺–N, 86.7% for TP, and 99.6% for coliform bacteria. The final effluent quality satisfied the Vietnamese discharge standard QCVN 14:2008/BTNMT (Column A). Stage-based analysis revealed that the anoxic unit played a key role in nitrogen removal, while the aerobic MBBR process contributed mainly to organic matter degradation. The membrane bioreactor ensured effective solid–liquid separation and produced a stable high-quality effluent. The study demonstrates that the integrated Anoxic–Aerotank–MBR configuration can provide an efficient and compact solution for decentralized wastewater treatment in institutional environments where land availability is limited. However, the study was conducted at laboratory scale, and further research is required to evaluate long-term operation, membrane fouling control, and energy consumption under large-scale conditions. The findings contribute new experimental data on compact hybrid biological–membrane systems for campus-scale wastewater treatment and provide practical insights for the development of decentralized wastewater management solutions in developing countries.