Ammonia Removal And Microbiological Analysis Of The Bio-trickling Filter Based On Aerobic Denitrification

The presence of oxygen can inhibit the anaerobic denitrification process during bio-trickling removal of NH3,and cause nitrate accumulation in the nutrient solution and eventually result in poor removal of nitrogenous pollutants.Based on the aerobic denitrification theory,this research verified the feasibility of applying aerobic denitrification to biological ammonia removal by evaluating the ammonia removal performance of an SND bio-trickling filter and the bioaugmentation performances of a traditional bio-trickling filer inoculated with aerobic denitrifying bacteria.First,taking the traditional bio-trickling filter as control,the NH3 removal performance of the SND bio-trickling filter,treating simulated NH3 containing gas which produced by the livestock houses,was investigated by monitoring the NH3 concentrations in the inlet and outlet gases,the nitrogen species in the nutrient solutions,and the microbial community structures by 16S rRNA technology.Then,we conducted a study on the NH3 removal performance of a traditional bio-trickling filter which stopped running for a couple of days and bioaugmented with aerobic denitrifying bacteria.The effect of the aerobic denitrifying bacteria Pseudomonas poae NL-4 on the NH3 removal of the bio-trickling filter was evaluated by comparing the NH3 removal efficiency and nitrogen species concentration in the nutrient solution before and after bioaugmentation.The main results were as follows:(1)The stare up performance of the SND bio-trickling filter A and the control bio-tricking filter B was compared under the same operating conditions.The SND bio-trickling filter exhibited a shorter start up period and a higher NH3 removal efficiency(up to 95%),moreover,The NH4+-N and NO3--N concentrations in nutrient solutions were significantly lower than that of the bio-trickling filter B(p<0.05).From the performance of the bio-trickling filters operated under the steady-state operation condition,the SND bio-trickling filter A was proved have higher simultaneous nitrification and denitrification ability than the control bio-trickling filter by analyzing the NH3 and N2O concentrations o in the inlet and outlet gases,as well as the NH4+-N?NO3--N?NO2--N and TOC concentrations in the nutrient solution of the bio-trickling filter.(2)The 16S rRNA high-throughput sequencing results showed that the SND bio-trickling filter.A had a higher relative abundance of microbial diversity than the control bio-trickling filter B.In addition,Proteobacteria and Bacleroidetes accounted for a large proportion in the SND bio-trickling filter,which may attribute to its high denitrification ability.(3)The short-term ceasing operation had a negative effect on the NH3 removal performance of the control bio-trickling filter B,especially,the NH4+-N?NO3--N and NO2--N concentrations in the nutrient solution were higher than before.The bioaugmentation of aerobic denitrifying bacteria Pseudomonas poae NL-4 can improve the NH3 removal efficiency of the bio-trickling filter B,moreover,the NH4+-N?NO3--N and NO2--N concentrations in the nutrient solutions were greatly reduced from 18 mg·L-1,175 mg·L-1 and 100 mg·L-1 to 1 mg·L-1,31 mg·L-1 and 3 mg·L-1,respectively.The control bio-trickling filter exhibited relatively high N2O emission after it was bioaugmented with aerobic denitrifying bacteria Pseudomonas poae NL-4.The N2O emission accounts for about 5.32%of the removed NH3by the bio-trickling filter.(4)The acetylene inhibition mechanism test indicated the denitrification process was the main production pathway of N2O,while the nitrification and nitrifier denitrification process were weakened.In summary,this study explored the start-up performance of SND bio-trickling filter and traditional bio-trickling filter,and explored the microbiological mechanism of SND bio-trickling filter for efficient nitrogen removal.The effect of biological nitrogen removal efficiency of NH4+-N?NO3--N and NO2--N on biological nitrogen removal efficiency was analyzed.