QiYuxuan,DingJing,CaoXiaoxin,et al.Optimization of Step-feed and Efficiency Improvement in a Multi?stage AO Process Based on Operational Diagnosis[J].China Water & Wastewater,2026,42(14):130-137.
Optimization of Step-feed and Efficiency Improvement in a Multi?stage AO Process Based on Operational Diagnosis
China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU]
volume:
第42卷
Number:
第14期
Page:
130-137
Column:
Date of publication:
2026-07-17
- Keywords:
- low C/N ratio; multi-stage AO process; specific nitrification rate; step-feed; carbon source distribution
- Abstract:
- Addressing the carbon source allocation imbalance in a multi-stage AO process at a wastewater treatment plant in Zigong under low influent C/N ratio conditions, this study systematically explained the contradictory issues of excessive organic loading in the primary aerobic zone and insufficient carbon source for denitrification in the secondary anoxic zone, based on historical operational data and biochemical process profiling. Through quantitative analysis of the specific nitrification rate of the activated sludge, an optimized calculation method for determining the step-feed distribution ratio was developed. Corresponding engineering modifications were implemented to redirect a portion of the raw influent to the secondary anoxic zone, achieving precise carbon source redistribution. Operational results demonstrated that after diverting 50% of the influent to the secondary anoxic zone, the system’s nitrogen removal efficiency was significantly enhanced. The effluent nitrate nitrogen concentration decreased by 1.95 mg/L compared to the parallel control train, while the dissolved oxygen concentration and specific nitrification rate in the primary aerobic zone increased markedly. Consequently, the sodium acetate dosing rate decreased from 17.18 mg/L to 10.55 mg/L, yielding an annual saving of approximately 190 000 CNY in carbon source costs. This research provides a theoretical framework and a practical case study for the optimization and control of carbon source allocation in wastewater treatment plants treating low C/N ratio wastewater.
Last Update:
2026-07-17