Nitrogen removal via simultaneous partial nitrification, anammox and denitrification (SNAD) process under high DO condition

Abstract

The simultaneous partial nitrification, anammox and denitrification (SNAD) process for treating domestic wastewater was investigated in a sequencing batch reactor (SBR). The SBR was operated with air flow rate of 500 L h at 30 °C. Domestic wastewater was used as influent and Kaldnes rings were used as biomass carriers. In the beginning, long aeration condition was implemented to cultivate nitrification biofilm. Afterwards, intermittent aerobic condition was conducted during the cycle operation. The influent organic matter loading rate was improved by reducing the aeration and mixing times. Consequently, when the SNAD biofilm reactor was fed with the organic matter loading rate of 0.77 (kg COD m d), the bio-bubbles appeared in the reactor and the total inorganic nitrogen (TIN) removal efficiency decreased. After the organic matter loading rate decreased to 0.67 (kg COD m d), the reactor showed excellent nitrogen removal performance. The TIN removal efficiency varied between 80 and 90 %, and the average TIN removal loading rate was 0.22 (kg TIN m d). Additionally, the scanning electron microscope (SEM) observation confirmed that the anammox bacteria located in the inner part of the carriers. Finally, the microbial community analysis of 16S rRNA gene cloning revealed that the anammox bacteria on the carriers consisted of three main genuses: Candidatus Brocadia sp., Candidatus Brocadia caroliniensis and Candidatus Brocadia fulgida.

Nitrogen removal in recirculating aquaculture water with high dissolved oxygen conditions using the simultaneous partial nitrification, anammox and denitrification system

“…The aerobic nitrite oxidation, anammox and denitrification activities of the SNAD biofilm in the biofilter were determined following the method of Zheng et al (2016). Briefly, the plastic media with biofilm used in the batch tests were taken out from the SNAD bioreactor at the end of the experiment.…”

“…Briefly, the plastic media with biofilm used in the batch tests were taken out from the SNAD bioreactor at the end of the experiment. The procedure for batch test was described in the methodology of Zheng et al (2016) -N (70 mg•L −1 ) and NaCH 3 COO (520 mg•L −1 ) were mixed for denitrification activity assay. In the anammox and denitrification activity measurement system, the flasks were pumped with high-purity N 2 gas (99.99%) for 15 min to remove the oxygen before being sealed.…”

“…However, the anammox and denitrification were not totally inhibited under high DO concentrations in this system. The inhibition of high DO on these anaerobic bioprocesses might be alleviated by the biofilm on the biofilter media (Zheng et al, 2016). Consequently, the SNAD bioreactor presented high performance for nitrogen removal to make the nitrogen contents meet the fishery water quality standards for fish growth.…”

Intensification and microbial pathways of simultaneous nitrification–denitrification in a sequencing batch biofilm reactor for seawater‐based saline wastewater treatment

“…[5][6][7][8][9][10] The conventional biological nitrogen removal processes including nitrification and denitrification processes are usually carried out in two different reactors or one reactor with two different operating periods because of the different environmental conditions required by functional nitrifying and denitrifying bacteria. 11 In recent years, studies have shown that nitrification and denitrification can be simultaneously completed in one reactor under aerobic conditions, namely a simultaneous nitrification-denitrification (SND) process. 12 Compared with conventional biological nitrogen removal processes, SND has the advantages of process simplicity, management conveniences, less land occupation, carbon source saving and high nitrogen removal efficiency.…”

Anammox and partial denitrification coupling: a review

“…Generally, lower DO (<2% air saturation) will inhibit the life activity of anammox bacteria (reversible), while higher DO (>18 air saturation) will irreversibly inhibit the bacteria. 120 Anammox bacteria will die when exposed to an excessive DO environment, and the living environment of DO for denitrifying bacteria is close to zero; therefore, the coupling of anammox and some denitrication bacteria needs to occur in a low oxygen environment. 58 Due to the mutual difference between oxidase and nitrite reductase, higher DO will inhibit nitrate reduction.…”