Studys On The Performance Of Nitrogen,Phosphorus And Ibuprofen Removal By Three-Dimensional Biofilm-Electrode

With the increase of the global population and the development of social economy,the shortages of water resources is becoming increasingly serious.In recent years,water reuse has been recognized as an effective way to address the problem of water shortages.WWTPs effluent,which has meet the discharged requirement,has high reuse value.However,most of China’s WWTPs effluent still contain high relatively levels of NO3--N,TP and PPCPs,in which ibuprofen is one of the highest detection rate.Long-term discharge of these substances poses a potential threat to the ecological environment and human health.Therefore,it is of great significance to explore a new technology to simultaneously achieve the removal of the NO3--N,TP and ibuprofen from WWTPs effluent.In this work,a three-dimensional electrode biofilm reactor(3DBER)was constructed,and started up the three-dimensional electrode biofilm coupled with Iron/Sufur(3DBER-Fe/S)system by exert micro-current.The effects of HRT on the performance of nitrogen and phosphorus removal was explored,and the mechanism of nitrogen and phosphorus removal was analyzed.The results showed that the removal efficiency of NO3--N,TN and TP in 3DBER-Fe/S system were 97.0%,85.7%and 73.5%,respectively.Under optimal HRT(6 h),the removal efficiency of NO3--N,TN and TP were 98.07%,82.09%and 79.7%,respectively.The mechanism of nitrogen and phosphorus removal in the 3DBER-Fe/S system was involved in physical,chemical and biological effects.The effects of current intensities on nitrogen and phosphorus removal performance and microbial communities in 3DBER-Fe/S system were investigated.The results showed that the current had no significant effect on the removal of NO3--N,but changed on the removal efficiency of TN and TP.Increasing the current intensities properly could promote the diversity of microbial communities in the system,while the excessive current effects significantly reduces the diversity of microbial communities.In this system,Proteobacteria,β-Proteobacteria and Thiobacillus were the dominant Phylum,Class and Genus,respectively.With the increases of current intensities,the relative abundance of different microorganisms were different significantly.The effects of current intensities on the microbial molecular ecological networks in the 3 DBER-Fe/S system were investigated.The results showed that the current intensities had significant impact on the overall networks in the system.The potential impacts of low current and suitable current to enhance the size and complexity of the networks.High current reduced significantly the size and complexity of the networks.The interaction among different microorganisms were decreased and appeared more competition among specis when current intensities increased from 20 mA to 200 mA.However,the interaction among different phylogenetic populations were reduced markedly and observed more positive correlations among species when current intensities higher 200 mA.Proteobacteria,Chloroflexi,and Firmicutes were the dominant Phylum in the networks,but there were significant differences at different current intensities.The key species in the networks were highly dynamic at different current intensities.Most of the key species were from Proteobacteria(39.4%)and Chloroflexi(27.3%),and Chloroflexi was more susceptible to change in current intensity than Proteobacteria.The effects of ibuprofen on the performance of nitrogen and phosphorus removal,microbial communities and microbial molecular ecological networks in 3DBER-Fe/S system were studied.The results showed that ibuprofen had no significant effect on the removal of NO3--N,but the TN and TP removal efficiency decreased.The removal efficiency of ibuprofen in the 3DBER-Fe/S system more than 97%when the system was stable operation.Illumina MiSeq sequencing revealed that Ibuprofen significantly reduced the microbial diversity,and altered the composition of microbial community.Molecular ecological network analysis showed that the size and complexity of the network were markedly reduced by Ibuprofen.Meanwhile,Ibuprofen weakened the overall network interaction among different phylogenetic populations,and led to more negative correlations,such as competition,predation and parasitism.