Control parameters in three-stage deammonification process for a mature leachate treatment based on a traditional Modified Ludzack-Ettinger process

Abstract

This study evaluated a three-stage deammonification process consisting of a sequentially Modified Ludzack-Ettinger (denitritation (DN) and partial nitritation (PN)) and anaerobic ammonium oxidation (ANAMMOX) for the treatment of mature leachate. In the initial stage, the nitrogen removal performance by two-stage deammonification was evaluated without an internal recycle (IR). The results showed that the ANAMMOX activity was severely inhibited from 0.19 to 0.03 gN/gVSS/d despite the stable partial nitritation. As inhibitors of ANAMMOX activity, the toxic effects of Refractory organic matter (ROM) and nitrite were found to deteriorate the stability of the process, and in particular, the ROM severely inhibited the activity. A three-stage deammonification process with the IR was implemented to alleviate the inhibition effects. As the IR was increased from 0 to 2Q, the ROM and nitrogen loads decreased by 35.3% and 27.8%, respectively. In addition, improved DN efficiency with external carbon sources allowed the ROM to serve as a potential electron donor for denitritation. With stabilization of ANAMMOX activity, the nitrogen removal performance rapidly stabilized. A nitrogen removal rate of 0.49 ± 0.02 kg/m3/d could be achieved with a nitrogen removal efficiency of 92.1 ± 2.1%.