Heterotrophic Ammonia and Nitrate Bio-removal Over Nitrite (Hanbon): Performance and microflora

A novel Heterotrophic Ammonia and Nitrate Bio-removal Over Nitrite (Hanbon) process, combining Short Nitrate Reduction (SNR) with Anaerobic Ammonia Oxidation (Anammox), was developed in a lab-scale continuous up-flow reactor. The substrate effects were investigated to characterize the performance of Hanbon process, and the corresponding microflora information was also revealed. Our results showed that the optimal substrate ratio of NH₄⁺-N:NO₃^--N:COD for the Hanbon process was 0.65:1:2.2. The volumetric nitrogen removal rate was up to 9.0 ± 0.1 kgN·m^-3·d^-1 at high influent substrate concentrations of NH₄⁺-N 375 mg L^-1, NO₃^--N 750 mg L^-1 and COD 1875 mg L^-1, which was superior to the reported values of analogous processes. Moreover, the effluent total nitrogen concentration was able to meet the strict discharge standard (less than 10 mg L^-1) at low influent substrate concentration of NH₄⁺-N 26 mg L^-1, NO₃^--N 40 mg·L^-1and COD 88 mg L^-1. Illumina-based 16S rRNA gene sequencing results showed that Halomonas campisalis and Candidatus Kuenenia stuttgartiensis were the dominant bacteria in the SNR section and Anammox section at high substrate concentration condition. However, Halomonas campaniensis and Candidatus Brocadia brasiliensis were raised significantly at low substrate concentration condition. Hanbon process provided in the present work was flexible of treating wastewater with various nitrogen concentrations, deserving further development.