Digested wastewater contains pathogenic microorganisms and high ammonia concentrations,which can pose a potential risk to public health.Effective removal of pathogens and nitrogen is crucial for the post-treatment of ...Digested wastewater contains pathogenic microorganisms and high ammonia concentrations,which can pose a potential risk to public health.Effective removal of pathogens and nitrogen is crucial for the post-treatment of digested wastewater.Partial nitrification-anammox is an energy-saving nitrogen removal process.Free nitrous acid(FNA),an intermediate product of partial nitrification,has the potential to inactivate microorganisms.However,the efficiency and mechanisms of FNA-related inactivation in pathogens during partial nitrification remains unclear.In this study,Enterococcus and Escherichia coli(E.coli)were selected to investigate the efficiency and mechanisms of FNA-related inactivation in partial nitrification process.The results revealed that 83%±13%and 59%±27%of E.coli and Enterococcus were removed,respectively,in partial nitrification process at FNA concentrations of 0.023−0.028 mg/L.When the concentration of FNA increased from 0 to 0.5 mg/L,the inactivation efficiencies of E.coli and Enterococcus increased from 0 to 99.9%and 89.9%,respectively.Enterococcus exhibited a higher resistance to FNA attack compared to E.coli.3D-laser scanning microscopy(3D-LSM)and scanning electron microscopy(SEM)revealed that FNA exposure caused the surface collapse of E.coli and Enterococcus,as well as visible pore formation on the surface of E.coli cells.4',6-Diamidino-2-phenylindole dihydrochloride n-hydrate(DAPI)/propidium iodide(PI)and biomolecule leakage confirmed that inactivation of E.coli and Enterococcus occurred due to breakdown of cell walls and cell membranes.These findings indicate that partial nitrification process can be used for the removal of residual pathogenic microorganisms.展开更多
The biocidal effects of free nitrous acid (FNA) have found applications in multiple units in an urban wastewater system, including sewer networks, wastewater treatment processes, and sludge treatment processes. Howeve...The biocidal effects of free nitrous acid (FNA) have found applications in multiple units in an urban wastewater system, including sewer networks, wastewater treatment processes, and sludge treatment processes. However, these applications are associated with chemical costs as both nitrite and acid are needed to produce FNA at the required levels. The recent discovery of novel acid-tolerant ammonia oxidizers offers the possibility to produce FNA from domestic wastewater, enabling the development of next-generation FNA-based technologies capable of achieving self-sustaining FNA production. In this study, we focus on the concept of in situ FNA generation facilitated by acid-tolerant ammonia oxidizers and highlight the multiple benefits it creates, after a brief review of the historical development of FNA-based technologies. We will discuss how wastewater systems can be made more energy-efficient and sustainable by leveraging the potential of acid-tolerant ammonia oxidizers.展开更多
The treatment of landfill leachate obtained from municipal solid waste(MSW) by using a lab-scale sequencing batch reactor(SBR) was studied.The aim of achieving and stabilizing partial nitrification and denitrification...The treatment of landfill leachate obtained from municipal solid waste(MSW) by using a lab-scale sequencing batch reactor(SBR) was studied.The aim of achieving and stabilizing partial nitrification and denitrification and the characteristics of advanced nitrogen removal were investigated.The experimental results showed that for 95 days running,stable partial nitrification with nitrite accumulation rate above 92.5% was achieved and maintained successfully.The stable biological nitrogen removal via partial nitrification and denitrification was realized and the average removal efficiency of NH+4-N and TN were above 97.2% and 91.7%,respectively.The DO,ORP and pH could be used as the process control parameters for SBR reactor,because the characteristic points on the profiles indicated exactly the nitrification and denitrification end point.The nitrite oxidizing bacteria(NOB) was more sensitive than ammonia oxidizing bacteria(AOB) to the free ammonia(FA) and free nitrite acid(FNA),so the activity of NOB was inhibited by the synergetic effect of highly concentrated FA and FNA in the SBR nitrification.Furthermore,the key factor of achieving and stabilizing partial nitrification and denitrification for a long time was optimization of nitrifying microbial population by the assistance of process control,which was proved by FISH analysis.展开更多
基金supported by the Natural Science Foundation of Anhui Province(China)(No.2208085ME145)the Key Project of Science and Technology in Anhui Province(China)(No.1801041130)the National Key R&D Program of China(No.2019YFC0408502).
文摘Digested wastewater contains pathogenic microorganisms and high ammonia concentrations,which can pose a potential risk to public health.Effective removal of pathogens and nitrogen is crucial for the post-treatment of digested wastewater.Partial nitrification-anammox is an energy-saving nitrogen removal process.Free nitrous acid(FNA),an intermediate product of partial nitrification,has the potential to inactivate microorganisms.However,the efficiency and mechanisms of FNA-related inactivation in pathogens during partial nitrification remains unclear.In this study,Enterococcus and Escherichia coli(E.coli)were selected to investigate the efficiency and mechanisms of FNA-related inactivation in partial nitrification process.The results revealed that 83%±13%and 59%±27%of E.coli and Enterococcus were removed,respectively,in partial nitrification process at FNA concentrations of 0.023−0.028 mg/L.When the concentration of FNA increased from 0 to 0.5 mg/L,the inactivation efficiencies of E.coli and Enterococcus increased from 0 to 99.9%and 89.9%,respectively.Enterococcus exhibited a higher resistance to FNA attack compared to E.coli.3D-laser scanning microscopy(3D-LSM)and scanning electron microscopy(SEM)revealed that FNA exposure caused the surface collapse of E.coli and Enterococcus,as well as visible pore formation on the surface of E.coli cells.4',6-Diamidino-2-phenylindole dihydrochloride n-hydrate(DAPI)/propidium iodide(PI)and biomolecule leakage confirmed that inactivation of E.coli and Enterococcus occurred due to breakdown of cell walls and cell membranes.These findings indicate that partial nitrification process can be used for the removal of residual pathogenic microorganisms.
文摘The biocidal effects of free nitrous acid (FNA) have found applications in multiple units in an urban wastewater system, including sewer networks, wastewater treatment processes, and sludge treatment processes. However, these applications are associated with chemical costs as both nitrite and acid are needed to produce FNA at the required levels. The recent discovery of novel acid-tolerant ammonia oxidizers offers the possibility to produce FNA from domestic wastewater, enabling the development of next-generation FNA-based technologies capable of achieving self-sustaining FNA production. In this study, we focus on the concept of in situ FNA generation facilitated by acid-tolerant ammonia oxidizers and highlight the multiple benefits it creates, after a brief review of the historical development of FNA-based technologies. We will discuss how wastewater systems can be made more energy-efficient and sustainable by leveraging the potential of acid-tolerant ammonia oxidizers.
文摘The treatment of landfill leachate obtained from municipal solid waste(MSW) by using a lab-scale sequencing batch reactor(SBR) was studied.The aim of achieving and stabilizing partial nitrification and denitrification and the characteristics of advanced nitrogen removal were investigated.The experimental results showed that for 95 days running,stable partial nitrification with nitrite accumulation rate above 92.5% was achieved and maintained successfully.The stable biological nitrogen removal via partial nitrification and denitrification was realized and the average removal efficiency of NH+4-N and TN were above 97.2% and 91.7%,respectively.The DO,ORP and pH could be used as the process control parameters for SBR reactor,because the characteristic points on the profiles indicated exactly the nitrification and denitrification end point.The nitrite oxidizing bacteria(NOB) was more sensitive than ammonia oxidizing bacteria(AOB) to the free ammonia(FA) and free nitrite acid(FNA),so the activity of NOB was inhibited by the synergetic effect of highly concentrated FA and FNA in the SBR nitrification.Furthermore,the key factor of achieving and stabilizing partial nitrification and denitrification for a long time was optimization of nitrifying microbial population by the assistance of process control,which was proved by FISH analysis.
