Reactor performance and microbial characteristics of CANON process with step-wise increasing of C/N ratio

Abstract

In this study, the nitrogen removal performance and microbial characteristics of completely autotrophic nitrogen removal over nitrite (CANON) process was investigated with a step-wise increasing of C/N ratio (0.5, 1, 2 and 4) in a membrane bioreactor. The microbial distribution of aerobic ammonia-oxidizing bacteria (AOB) and anaerobic AOB (AAOB) was analysed by fluorescence in situ hybridization (FISH). Results showed that the denitrification ratio rose up correspondingly with the increase of influent C/N, and nitrogen removal rate (NRR) reached the maximum when C/N was 1 due to the harmonious work of denitrification and CANON. However, NRR decreased when influent C/N was more than 2. The threshold C/N ratio of CANON process was 2.2; so the sewage with a high C/N ratio should be pretreated by combining with pre-oxidation of organics or anaerobic-energy-producing process. FISH results showed decreasing numbers of both AOB and AAOB with the addition of organics.

Keywords:

• CANON
• C/N
• nitrogen removal
• denitrification
• FISH

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

This work was supported by Programme for the National Natural Science Foundation of China (NSFC No. 50878003) and PhD Programme of Zhengzhou University of Light Industry – China (2014BSJJ055).

Supplemental data

Supplemental data for this article can be accessed at [http://dx.doi.org/10.1080/09593330.2015.1070921]