Fig. 3. Performance of M-344 sulfamethazine-added reactor during different phases. (a) Effluent nitrogen concentration and influent antibiotic concentrations (AC). (b) Total nitrogen load rate (NLR), nitrogen removal rate (NRR) and total nitrogen removal efficiency (TNRE). (c) Reaction molar ratios (RS = NO2−-N conversion/NH4+-N depletion and RP = NO3−-N production/NH4+-N depletion) and hydraulic retention time (HRT).Figure optionsDownload full-size imageDownload as PowerPoint slide
3.3. Physiological dynamics
Fig. 4. Dynamics of the specific anammox activity (SAA) during different phases.Figure optionsDownload full-size imageDownload as PowerPoint slide
Remarkably, the heme c responses of the AnAOB were discriminative (Table 2). The suppression of AMX negligibly reduced the heme c content, whereas SMZ caused a slight decline (by approximately 15% on Day 30) when the SMZ concentration was above 30 mg L−1. The heme c content adapted over time and finished at levels slightly higher than the initial level. In contrast, the response of AnAOB to FF was rapid and reduced the heme c content to 80% of the initial level within 3 days. Afterward, R3 adapted over time, and the heme c levels returned to their initial levels after the termination of FF addition. These differences were because of the difference in the bacterial target sites inhibited by these three antibiotics. FF inhibits protein synthesis (Ding et al., 2015), and heme c is an indispensable component of the anammox key enzymes.