Evaluation of a novel oxidation ditch system with dual DO control technology for biological nutrient removal by mass balance analysis

A novel pilot-scale oxidation ditch (OD) system with an anaerobic tank and dual dissolved oxygen (DO) control technology was used to treat raw domestic wastewater during 310 days of operation. Three intensive sampling sessions indicated that the dual DO control technology could create stable aerobic and anoxic zones along the main ditch, even with large influent fluctuations. Dramatic total nitrogen (TN), total COD, and total phosphorus removal efficiencies were achieved within ranges of 78–90%, 83–91%, and 69–82%, respectively. June nitrogen balance results revealed that 60% of influent TN was denitrified and that 92% denitrification occurred in the main OD, demonstrating the advantage of the dual DO controls. In addition, COD balance values showed that 67% of the mineralized COD was due to denitrification, and aerobic oxidation was minimized. With lower influent BOD/N ratios of 4.0–4.7, significant TN removal performances were obtained in this OD system. Maximizing COD for denitrification and minimizing aerobic degradation suggest that this novel OD system shows promise for highly effective sewage treatment with effective COD consumption.

► A novel OD system with dual DO control technology was evaluated by mass balances.
► The novel OD created stable aerobic/anoxic zones with large influent fluctuations.
► TN removal efficiencies were 77–90% with lower influent BOD/N ratios of 4.0–4.7.
► Maximizing COD for denitrification and minimizing aerobic degradation were achieved.
► The novel OD could realize effective COD consumption by the dual DO control technology.