Treatment Of Train Toilet Wastewater By Shortcut Nitrification And Denitrification

With the continuous construction of my country’s railway network and the continuous increase in the number of passengers transported,the amount of sewage generated from the toilets of passenger trains has increased significantly.Due to the increasingly strict and standardized urban drainage requirements,the sewage from the train toilets unloaded in the train station section has an urgent need for pollutant treatment.The quality of the sewage from the train toilets is characterized by high nitrogen concentration and low carbon-nitrogen ratio.The traditional biological denitrification process is difficult to meet the discharge requirements,and the treatment cost is high.In this paper,a sequencing batch reactor(SBR)was used to study the denitrification performance of the short-range nitrification and denitrification process for the treatment of passenger train toilet sewage.This paper studies the effect of different influent C/N ratios on the denitrification performance of short-range nitrification and denitrification,and explores the denitrification status of toilet waste water under the condition of external carbon source,so as to provide an efficient and economical treatment method for toilet waste water in the EMU depot.Learn from.The thesis achieved the following research results:(1)For the artificial train toilet sewage,the TN removal rates are 25.1%,52.9%and 72.0% respectively,and the average nitrite accumulation rate is 86.65% under the condition of controlling the influent C/N ratio of 1.0,2.0 and 3.0.The system realized stable short-cut nitrification and denitrification,and with the increase of influent C/N ratio,the denitrification efficiency of the system for sewage from the simulated toilet bowl was improved.(2)The particle size distribution of SBR activated sludge is 10~1000 μm,which cultivates part of granular sludge and increases the settling performance of sludge.The sludge SVI is 60~80 m L/g,and the system MLSS is basically maintained at 8 ~ 9 g/L.SBR reactor has good impact load resistance and denitrification efficiency.(3)Shortcut nitrification and denitrification process directly treats the effluent of anaerobic septic tank in EMU section.Due to the low C/N water quality,the TN removal rate is 31.4%,and the effluent quality is difficult to meet the discharge standard.However,the effluent NO2--N/NH4+-N ratio is 1.04± 0.33.By optimizing the reaction system,SBR effluent can be used as the influent of anaerobic ammonia oxidation reactor.(4)Under the condition of adding methanol carbon source,the C/N ratio of train toilet sewage was adjusted to about 3.0.When microorganisms can use methanol as carbon source for denitrification,the average TN removal rate of short-path nitrification and denitrification process can reach 72.3%.(5)The microbial detection results of the activated sludge in the reactor showed that the main bacterial phylum in the activated sludge system was Proteobacteria,and its abundance showed an increasing trend from 35.4% to 50.4% and 87.3%.The main dominant bacterial genus in the nitrosation process is Nitrosomonas.With the increase of COD concentration in the influent,the abundance of denitrifying bacteria(Ottowia,Themomonas,Paracoccus,etc.)increased.