Influence of Tourmaline on the Activity of ANAMMOX Bacteria and ANAMMOX Reaction

The performance of the anaerobic ammonium oxidation (ANAMMOX) process was investigated in two identical sequencing batch reactors (SBRs) [designated as SBR1 (tourmaline addition) and SBR2 (check reactor)] at nitrogen loading rates (NLRs) varying from 0.73 to $4.90\mathrm{g}\mathrm{N}/(\mathrm{L}·\mathrm{d})$ and constant hydraulic retention time of 6 h. Both of the removal efficiency of ammonia nitrogen and total nitrogen were higher in SBR1 than that in SBR2 with increased NLR. The specific ANAMMOX activity (SAA) of the ANAMMOX sludge increased from 3.23 to 12.87 and from 2.83 to $8.53\mathrm{mg}\mathrm{N}/[\mathrm{g}\mathrm{volatile}\mathrm{suspended}\mathrm{solids}(\mathrm{VSS})/\mathrm{h}]$ in the SBR1 and SBR2, respectively, which increased approximately 4.0- and 3.0-fold. As compared with SBR2, SBR1 possessed the ANAMMOX sludge with higher yield coefficient and decay constant, i.e., $0.2608\mathrm{g}\mathrm{biomass}/\mathrm{g}$ substrate and $0.011/\mathrm{d}$, respectively. According to the modified Stover–Kincannon model, the maximal substrate removal rate ($U_{\max }$) and saturation rate constant ($K_b$) of SBR1 were suggested as $125.0\mathrm{g}\mathrm{N}/(\mathrm{L}·\mathrm{d})$ and $151.7\mathrm{g}\mathrm{N}/(\mathrm{L}·\mathrm{d})$, respectively, which were much higher than $21.6\mathrm{g}\mathrm{N}/(\mathrm{L}·\mathrm{d})$ and $26.2\mathrm{g}\mathrm{N}/(\mathrm{L}·\mathrm{d})$ of SBR2. Results showed that SBR1 obtained the excellent and stable performance, and the modified Stover–Kincannon model could be used to describe the kinetic behavior or design ANAMMOX reactor enhanced by tourmaline.