Enhancing nitrogen removal in combined sewage overflows by using bio-fluidized bed with ceramic waste powder carriers: effects and mechanisms.

Micron-size ceramic waste powder (< 75 μm and 75-150 μm) was used as the carrier in a high-concentration powder carrier bio-fluidized bed (HPB) to treat simulated overflow sewage (CSOs). The sludge extracellular polymers (EPS), electron transfer capacity of EPS, nitrogen removal pathways, and microbiological characteristics were analyzed to gain insights into the nitrogen removal pathways and mechanisms. The results showed that only the effluent from the HPB (< 75 μm) could meet the stringent pollutant discharge standards in China of 50 mg/L for COD and 15 mg/L for total nitrogen from beginning to end.