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The short-range nitrification-denitrification process refers to inhibiting or eliminating nitrite oxidizing bacteria in the system, so that the conversion of nitrogen is limited to the oxidation of NH4+ to NO2-, In turn, NO2- is reduced to N2, eliminating the nitrate conversion step and saving system aeration and carbon source addition
.
However, in high ammonia nitrogen loading systems, short-range nitrification units tend to be prone to instability
due to the high sensitivity of ammonia-oxidizing bacteria to external environmental conditions.
The stability of the influent concentration is one of the important measures to ensure the stability of the process, but the influent concentration is difficult to ensure stability in actual operation, and the system is often affected
by the influent ammonia nitrogen.
Therefore, it is of great practical significance
to enhance the stability of the system by understanding and strengthening the structure of the microbial community.
Assistant researcher Cao Qin, a member of the biomass energy project team of the Chengdu Institute of Biology, Chinese Academy of Sciences, set up and operated two sets of laboratory-scale sequential batch nitrification bioreactors, one reactor was connected to the synthetic wastewater (CN system) with a C/N of 0.
6, and the control group was introduced Synthetic wastewater (N system)
with C/N 0.
After the two systems are in stable operation, an overloaded ammonia nitrogen inlet load is used to circulate the shock system
.
The experiments found that the ammonia oxidation efficiency and nitrite accumulation rate of the CN system were higher than those of the N system during the whole operation, and were less
affected by the impact of ammonia nitrogen influent water.
Through microbial community diversity analysis and community dynamics analysis, it was found that VLR and FA were positively correlated with the turnover direction of microbial communities in the stabilization stage and the impact stage, indicating that FA was the selective stress factor of microbial community, which in turn drove it Turnover
of microbial communities in the CN system.
Nitrosomonas is the main autotrophic AOB of the CN system and exhibits resistance to ammonia nitrogen shock loads
.
HN-AD bacteria in the CN system (Pseudomonas, Flavobacterium, and Paracoccus) rapidly increases in relative abundance during the shock phase, exhibiting similar functions to Nitrosomonas, increasing the functional redundancy of the system
.
The functional prediction of 16S amplicon sequencing results using PICRUSt showed a significant positive correlation between the sum of the relative abundances of nitrifying microorganisms and the Pearson correlation analysis of ammonia monooxygenase (P 0.
008 , R2 0.
42593), indicating Nitrosomonas, Pseudomonas, Flavobacterium And Paracoccus is indeed the microorganism
that performs nitrification in the CN system.
Moreover, the increase of the relative abundance of ammonia monooxygenase and hydroxylamine oxidase in the shock group indicates that the FA stress factors have redundancy, thereby maintaining the nitrogen removal efficiency and stability
of the system.
This research was supported
by the Western Light Project (2019XBZG_JCTD_ZDSYS_001) and others.
The related scientific research results "Nitrification resistance and functional redundancy maintain the system stability of partial nitrification in high-strength ammonium wastewater system" was published in In
the journal Bioresource Technology.
Original link
