The treatment of wastewater from university laboratories is receiving increasing attention. However, due to constraints on campus land use, wastewater facilities at older campuses are hampered by municipal pipelines, building layouts and budgetary limitations, thereby impeding the development of university laboratories and academic disciplines. Enhancing wastewater management in old campus laboratories helps prevent environmental pollution, control disease transmission, safeguard the health of staff and students and support high-quality scientific research in higher education institutions.

This study conducts sampling tests on wastewater discharged from laboratories on an old campus. Based on the water quality test results and flow characteristics, the effluent quality targets for the new wastewater treatment facility are determined. The selected wastewater treatment process is an integrated advanced oxidation-flocculation-sedimentation-anaerobic-anoxic-oxic (A²/O) process. The main facilities are located underground beneath a roadway. The main equipment materials utilise integrated stainless steel to ensure sealing integrity. The project team modifies the existing drainage network, surveys and compares the piping materials of the existing building’s water supply and drainage systems and selects reliable old pipes for reuse. The project utilises existing drainage wells as wastewater collection chambers. Following disinfection in the treatment tank, the effluent is discharged through a Parshall flume flow metre into the original drainage outlet. This project incorporates baffle plates within the flocculation-sedimentation tank to enhance reaction efficiency. These plates create agitation and flow guidance, minimise vortex formation and ensure complete sedimentation within the tank. The system employs microcomputer control to automate pump operation. Simultaneously, it issues control commands for each independent anaerobic, anoxic and aerobic reaction zone, regulating influent flow, recirculation ratios and carbon source distribution. This design achieves varying degrees of denitrification and phosphorus removal. Finally, this article evaluates the project’s effectiveness from three aspects: effluent quality, investment costs and operational costs.

The operational results of the wastewater treatment facilities indicate the following: (1). All effluent quality parameters meet the Grade Ⅱ standards of the Guangzhou Wastewater Discharge Standards, with suspended solids (SS) at 35 mg/L and heavy metal chromium at 0.12 mg/L, achieving removal rates of 83.3% and 70%, respectively. (2). The total investment for the renovation project amounts to approximately CNY 1585700. With a daily wastewater treatment capacity of 80 tonnes, the unit investment per tonne treated stands at CNY 19800. This result represents a higher investment efficiency than that of the ‘micro-electrolysis-flocculation-sedimentation-contact oxidation’ small-scale treatment station. (3). The comprehensive operating cost is approximately CNY 0.9 per cubic metre. Compared with other renovation projects, this project achieves over 20% savings in operational and maintenance expenses. (4). Compared with aboveground wastewater treatment stations, this project reduces the land area requirement by 50%.

University laboratory wastewater is characterised by low volume and dispersed sources. Compared with conventional methods, the integrated wastewater treatment unit employing the advanced oxidation-flocculation-sedimentation-A²/O process demonstrates advantages, including a reduced footprint, lower initial investment, high automation and minimal operational costs. Constrained by the limited space available on the old campus, the selection of an integrated underground wastewater treatment facility balances campus aesthetics with equipment durability. Refining sludge digestion technology reduces secondary pollution, minimising the environmental impact throughout the facility’s lifecycle. This approach supports the national ‘dual carbon’ goals, offering a novel solution for laboratory refurbishment and wastewater management on old campuses.