7 mg/L reached 90.1% after 98-day operation, much higher than that of control (41.6%) without NO3- addition. Adding NO3- in the digester to trigger Fe(III)/Fe(II) cycle for removing ammonium is just equivalent to an anammox-like process using NO3- as terminal electron acceptor to oxidize NH4+. Water quality sensors are often spatially distributed…[Read more]