| With the increasing utilization of nanomaterials, it was inevitable that large amounts of NPs released into municipal wastewater treatment system and posed new threat to Biological wastewater treatment system. In this study, two kinds of typical nanometer dioxide were selected to determine their influence on the security of municipal biological wastewater treatment system. This work can provide theoretical basis for the stable operation of biological wastewater treatment system.This article explored the interaction between pollutants and NPs (TiO2NPs and ZnO NPs) in domestic sewage via ultra-filtering the domestic sewage. With the increase of the molecular weight, the potential value of domestic sewage fraction decreased. When added nanoparticles to the domestic sewage fraction, the surface potential change rule of particles was still unchanged and the surface potential reduced with the increase of the molecular weight. For low molecular domestic sewage F1and F2, adsorption was the preponderant factor in the interaction with nanoparticles and the particle size increased. While for high molecular domestic sewage F3and F4,the electrostatic repulsive force played dominant roles and led to aggregate dispersed and particle size reduction. The FTIR spectra of each domestic sewage fraction were similar, but the peak intensity and peak width of individual absorption peak were different. Low molecular domestic sewage fractions contain more carbinol and carboxyl functional groups. The carboxyl functional groups ofFTIR spectra had a marked shift after the adsorption between domestic sewage fraction and nanoparticles, which indicate that the carboxyl functional groups are the main functional group when organic particles in sewage interact with nanoparticles. Low molecular weight fractions and nanoparticles have higher degree interaction, because for low molecular weight fractions ligand exchange were the main action mode while for high molecular weight fractions electrostatic repulsion played an important role.It was found that5mg/L TiO2NPs had no effects on wastewater ammonia nitrogen and organic matters removal after nanoparticles were added to SBR, whereas25and100mg/L TiO2NPs was observed to decrease ammonia nitrogen and organic matters removal efficiency. The influence of100mg/L TiO2NPs on ammonia nitrogen and organic matters removal was earlier than25mg/L TiO2NPs. However, biological phosphorus removal was unaffected after adding nanoparticles to the system. Compared with TiO2NPs, lmg/L ZnO NPs had no influence on ammonia nitrogen and organic matters removal. Howere, the presence of5and25mg/L of ZnO NPs significantly decreased ammonia nitrogen and organic matters removal efficiencies, but the system had a certain degree of recovery in a week. Meanwhile, we discovered that25mg/L ZnO NPs exerted great influence over system phosphorus removal. Correspondingly, the system release phosphorus effect significantly reduced, and the effluent phosphorus concentration increased. Nevertheless, land5mg/L ZnO NPs had no impact on system phosphorus removal.It was report that the inhibition of the same concentration nanoparticles on sludge biological activity since was as follows:INT-electronic transfer system (INT-ETS)<activated sludge than good oxygen rate (SOUR)<TTC-electronic transfer system (TTC-ETS).Therefore, TTC-ETS has higher sensitivity to characterize the toxicity of nanoparticles and can be used as an effective evaluation index of toxic effects.When system was fed with25and100mg/L TiO2NPs and5mg/L ZnO NPs respectively, the contents of polysaccharide and protein in EPS had different degree reduction with the extension of exposure time. For system added with25mg/L ZnO NPs, protein content in EPS decreased at different level with the extension of exposure time, but the polysaccharide content in EPS is always in low concentration range. This study revealed that TiO2NPs (25and100mg/L) and ZnO NPs (5and25mg/L) could induce EPS components molecular structure change of active sludge. |
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