Integration of denitrifying phosphorus removal via nitrite pathway, simultaneous nitritation-denitritation and anammox treating carbon-limited municipal sewage.

•Achievement of nitritation was a prerequisite to improve nutrients removal.•Denitrifying P removal via nitrite was the key pathway in anoxic zone.•Simultaneous nitritation–denitritation contributed to N removal in aerobic zone.•PCR verified presence of anammox bacteria with the largest of 1.32×106copies/gVSS.•Combining denitrifying P removal, SND with anammox to solve carbon-limited problem.