Nitritation-denitrification process as a pretreatment of ANAMMOX to remoyi nitrogen from piggery wastewater

Piggery wastewater with low C/N was treated by using nitritation-denitrification process to attain a suitable influent for ANAMMOX at ambient temperature (13-20 degrees C) without pH control. By using this process, part of total nitrogen and COD were removed, the ratio of ammonium and nitrite reached around 1:1 and the pH was about 7.8, which were favorable for ANAMMOX. The average removal percentage of COD and total nitrogen were 64.3% and 49.1%, respectively. Afterwards, nitrogen removal performance by followed ANAMMOX process was also investigated. Stable performance of ANAMMOX process was achieved and the removal percentage of ammonium, nitrite and total nitrogen were 91.8%, 99.3% and 84.1%, respectively.