| Bioreactors are widely used for wastewater treatment owing to the advantages of simple process and low operation cost.However,industrial wastewater with nitrogen-containing heterocycles(N-heterocyclic)is so difficult to be biodegraded due to part of its complex component that it is necessary to establish suitable wastewater treatment methods.Bioaugmentation is a way to improve the processing capacity of bioreactors by adding bacteria with specific pollutant-degrading functions,which has been widely studied in recent years.The purpose of this dissertation is to investigate the degradability and environmental tolerance of sequencing batch reactor(SBR)bioaugmented with two aromatics-degrading strains,Acinetobacter sp.JW and Comamonas sp.Z1,for treatment of N-heterocyclic-containing wastewater(indole,pyridine and quinoline).The effects of changes in N-heterocyclic concentration,pH and salinity on SBR performance were investigated,and the characteristics of activated sludge and microbial community were determined,which should provide a theoretical basis for actual bioaugmentation in wastewater treatment.The influence of N-heterocyclic concentration(100～200 mg/L)on SBR performance was determined.During the 90 days long-term operation,the bioaugmented group(group B)and the non-bioaugmented group(group C)showed good removal efficiencies(>94%)for N-heterocyclic and chemical oxygen demand(COD).Quinoline in group B could be completely degraded within 10 h at the starting period,while it could not be completely degraded in 40 h in group C.As the concentration of N-heterocyclic increased,nematodes that contribute to the improvement of sludge resistance could be observed in the sludge of group B,but not in group C.The non-metric multidimensional scaling(NMDS)analysis showed that the microbial communities of group B were clearly separated from those of group C.Dokdonella and Comamonas were enriched in SBRs.Other dominant strains in group B were Pseudoxanthomonas,Flavobacterium and Alcaligenes,while Thermomonas,Limnobacter,Luteimonas and Rhodanobacter were predominant in group C.Phylogenetic Investigationof Communities by Reconstruction of Unobserved States(PICRUSt)showed that the abundances of genes related to xenobiotics degradation and metabolism in group B were higher than those in group C.The influence of influent pH(8～12,4～6)on SBR performance was investigated.As the pH increased(>8)or decreased(<6),the COD removal efficiency of SBR fluctuated,and the lowest efficiency(80%)was observed at influent pH of 12 and 5 At influent pH of 12,nematodes could still be observed in group B,but no nematode were detected at pH of 4.Under the conditions of acid(pH=4)or alkali(pH=12)influent,the protein contents in the sludge were higher than that those under neutral condition.NMDS and principal coordinate analysis(PCo A)showed that the communities of group B were also separated from those of group C at the influent pH of 4 and 12.Alicycliphilus,Brevundimonas and Arenimonas were the dominant bacteria in group B.In group C,Roseomonas,Elioraea and Thaurea were the dominant genus.The network analysis showed that dominant bacteria in group B(Arenimonas and Brevundimonas)had a significant positive correlation(p<0.05)with N-heterocyclic removing bacteria(Dokdonella),but the dominant bacteria in group C(Roseomonas,Elioraea and Thauera)had a significant negative correlaton(p<0.05)with N-heterocyclic removing bacteria(Thermomonas).PICRUSt showed that the relative abundances of the genes related to glycolysis in group C were higher than those in group B,but the relative abundances of functional genes related to amino acid related enzymes were lower than those in group B.The influence of influent salinity(1%～0.3%)on SBR performance was examined.As the salinity changes,the treatment efficiencies of pyridine fluctuated significantly.The removal efficiency of it in group B dropped to 88%,while in group C,the treatment efficiency was61% on the 29 th day.With the decrease of salinity,the sedimentation performance of sludge in SBR was restored.The contents of polysaccharide and protein in sludge of group B were higher than those of group C.NMDS and PCo A indicated that the structure of microbial communities were significant difference between group B and group C.Paracoccus,Hyphomicrobium and Aquamicrobium in group B were the dominant genera,while Chryseobacterium,Stappia and Pusillimonas in group C were the dominant genera.The dominant salt-tolerant bacteria(Paracoccus and Hyphomicrobium)in group B had a significant positive correlation(p<0.05)with others,and the salt-tolerant dominant bacteria in group C(Chryseobacterium)had a significant negative correlaton(p<0.05)with N-heterocyclic removing bacteria(Thauera).The relative abundances of genes related to xenobiotics biodegradation,energy metabolism and metabolism in SBR were relatively high,and their abundances were not significantly affected by influent salinity. |
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