Low-carbon urban sewage in relatively high water quality characteristics of nitrogen and phosphorus, due to the low organic matter content, using conventional denitrification process cannot meet the needs of anoxic denitrification stage of carbon source, cause the denitrification process is blocked, appreciation, and inhibition of heterotrophic aerobic bacteria make assimilation of ammonia nitrogen (NH4 - N) decreased, thus greatly affected the denitrification effect of sewage treatment plant
The denitrification rate of sodium acetate was much higher than that of methanol and starch. The main reason is that sodium acetate is a low molecular organic salt and is easy to be used by microorganisms.
In addition, sodium acetate does not belong to dangerous goods itself, is convenient for transportation and storage, and its absolute price is also cheaper than methanol. Therefore, for some established sewage treatment plants, sodium acetate has more advantages than methanol when additional carbon source is needed due to its land limitation.
The action principle of sodium acetate in sewage treatment
In the stage of anoxic denitrification, the nitrate nitrogen (NO3-n) in sewage is reduced to gaseous nitrogen (N2) under the action of denitrifying bacteria. Denitrification is a biochemical reaction performed by heterotrophic microorganisms that use oxygen in nitrate (NO3-N) as an electron acceptor and organic matter (carbon source) as an electron donor at extremely low dissolved oxygen concentrations.
In practical engineering, if sewage BOD5∶N < 4:1 enters the denitrifying section, additional carbon source should be considered, BOD5 /N≥4, and the denitrification can be considered complete.
