Design and operational performance of a modified Bardenpho process in a wastewater treatment plant

The design daily treatment capacity of the newly built sewage treatment plant is 100000 m3/d. The inflow contains about 15% industrial wastewater， resulting in fluctuation coefficients in both water quality and quantity ranging from 1.2 to 1.5， with a proportion of difficulty degrading organic matter （measured as COD） greater than 35%， and a TN concentration of up to 55 mg/L. To ensure stable effluent quality and enhance the system’s resistance to shock loads， a modified Bardenpho process was adopted. This process integrates multi-point influent distribution and an additional post-anoxic and post-aerobic configuration， in combination with auxiliary units such as an equalization basin， a high-efficiency sedimentation tank， and a denitrifying deep-bed filter. These design features collectively aim to strengthen nitrogen and phosphorus removal efficiency as well as operational flexibility. During the commissioning and operational period， the process demonstrated excellent pollutant removal performance： the average removal efficiencies of COD， NH3-N， TN， and TP were 96.10%， 98.24%， 83.89%， and 98.29%， respectively. The corresponding effluent concentrations stabilized at 15.4 mg/L， 0.57 mg/L， 7.94 mg/L， and 0.12 mg/L， all of which consistently outperformed the Class 1A standard specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants （GB 18918—2002）. These findings confirm that the modified Bardenpho process is highly effective in treating wastewater with high nitrogen loads and refractory organic components， showing strong adaptability and system stability. Moreover， its configuration enhances carbon source utilization efficiency while reducing operational energy consumption. The design parameters and operational experiences from this project can serve as practical references for the planning， design， and optimization of large-scale municipal wastewater treatment plants， particularly those receiving a significant fraction of industrial wastewater.