Ecological restoration for the Liangtan river by Rotating biological contactors combined with hybrid constructed wetlands

ABSTRACT

Rotating biological contactors (RBCs) were first used as pretreatment units for hybrid constructed wetlands (HCWs) in practical engineering to treat polluted river water. The experimental results during 2019–2021, except the period of global COVID-19 pandemic (January to April, November and December in 2020), indicated the average removal efficiencies of ammonia nitrogen (NH4+–N), total phosphorous (TP), and chemical oxygen demand (COD) were 95.06%, 41.03%, and 45.46%, which met the Chinese Environmental Quality Standards Ⅰ, Ⅲ, Ⅳ (CEQS Ⅰ, Ⅲ, Ⅳ), respectively. RBCs and HCWs had synergistic and complementary effects on purification efficiency, especially on nitrogen removal. The remarkable nitrification efficiency of RBCs was not influenced by temperature and influent loads. The relative abundances of microorganisms at HCWs in cold seasons were comparable to that in warm seasons, which promoted the recovery of decontamination efficiency after overwintering. These results support RBCs combined with HCWs (R-HCWs) is an effective polluted river purification process, providing a new perspective on water ecological restoration.