Efficient step-feed partial nitrification, simultaneous Anammox and denitrification (SPNAD) equipped with real-time control parameters treating raw mature landfill leachate

An innovative step-feed partial nitrification, simultaneous Anammox and denitrification (SPNAD), equipped with real-time control parameters, achieved efficient nitrogen removal from raw mature landfill leachate. The variables pH and ORP served as real time on-line parameters to flexibly control the durations of aerobic and anoxic. A nitrogen removal efficiency (NRE) of 98.7% and nitrogen removal rate (NRR) of 0.23 kg m(-3)d(-1) were obtained at the influent NH4+-N, SCOD and total nitrogen (TN) of 1000 +/- 250 mg L-1, 1100 +/- 200 mg L-1, and 1300 +/- 75 mg L-1, respectively. Mass balance research demonstrated that Anammox contributed 69.3% to nitrogen removal and denitrification contributed 15.7%. A significant change in the Anammox community structure occurred (ca. Brocadia from 0.26% to 2.13%, ca. Kuenenia from 0.29% to 0.02%). This change is mainly attributed to different kinetic strategies (R-strategist of ca. Brocadia and K-strategist of ca. Kuenenia). Further study revealed the co-existence of functional microorganisms Nitrosomonas (3.0%), Cadidams-Brocadia (2.13%), and Thauera (25.3%).