Evolution and health risk of indicator microorganisms in landscape water replenished by reclaimed water

As an important means to solve water shortage,reclaimed water has been widely used for landscape water supply.However,with the emergence of large-scale epidemic diseases such as SARS,avian influenza and COVID-19 in recent years,people are increasingly concerned about the public health safety of reclaimed water discharged into landscape water,especially the pathogenic microorganisms in it.In this study,the water quality and microorganisms of the Old Summer Palace,a landscape water body with reclaimed water as the only replenishment water source,were tracked through long-term dynamic monitoring.And the health risks of indicator microorganisms were analyzed using Quantitative Microbial Risk Assessment(QMRA).It was found that the concentration of indicator microorganisms Enterococcus(ENT),Escherichia coli(EC)and Fecal coliform(FC)generally showed an upward trend along the direction of water flow and increased by more than 0.6 log at the end of the flow.The concentrations of indicator microorganisms were higher in summer and autumn than those in spring.And there was a positive correlation between the concentration of indicator microorganisms and COD.Further research suggested that increased concentration of indicator microorganisms also led to increased health risks,which were more than 30%higher in other areas of the park than the water inlet area and required special attention.In addition,(water)surface operation exposure pathway had much higher health risks than other pathways and people in related occupations were advised to take precautions to reduce the risks.

Partial anammox achieved in full scale biofilm process for typical domestic wastewater treatment

The slow initiation of anammox for treating typical domestic wastewater and the relatively high footprint of wastewater treatment infrastructures are major concerns for practical wastewater treatment systems.Herein,a 300 m^(3)/d hybrid biofilm reactor(HBR)process was developed and operated with a short hydraulic retention time(HRT)of 8 h.The analysis of the bacterial community demonstrated that anammox were enriched in the anoxic zone of the HBR process.The percentage abundance of Candidatus Brocadia in the total bacterial community of the anoxic zone increased from 0 at Day 1 to 0.33%at Day 130 and then to 2.89%at Day 213.Based upon the activity of anammox bacteria,the removal of ammonia nitrogen(NH_(4)^(+)-N)in the anoxic zone was approximately 15%.This showed that the nitrogen transformation pathway was enhanced in the HBR system through partial anammox process in the anoxic zone.The final effluent contained 12 mg/L chemical oxygen demand(COD),0.662 mg/L NH_(4)^(+)-N,7.2 mg/L total nitrogen(TN),and 6 mg/L SS,indicating the effectiveness of the HBR process for treating real domestic wastewater.

Catalytic ozonation in advanced treatment of kitchen wastewater:multi-scale simulation and pilot-scale study

Catalytic ozonation is regarded as a promising technology in the advanced treatment of refractory organic wastewater.Packed-bed reactors are widely used in practical applications due to simple structures,installation and operation.However,mass transfer of packed-bed reactors is relatively restrained and amplified deviations usually occurred in scale-up application.Herein,a multi-scale packed-bed model of catalytic ozonation was established to guide pilot tests.First,a laboratory-scale test was conducted to obtain kinetic parameters needed for modeling.Then,a multi-scale packed-bed model was developed to research the effects of water distribution structure,catalyst particle size,and hydraulic retention time(HRT)on catalytic ozonation.It was found that the performance of packed bed reactor was increased with evenly distributed water inlet,HRT of 60 min,and catalyst diameter of about 3-7 mm.Last,an optimized reactor was manufactured and a pilot-scale test was conducted to treat kitchen wastewater using catalytic ozonation process.In the pilot-scale test with an ozone dosage of 50 mg/L and HRT of 60 min,the packed-bed reactor filled with catalysts I was able to reduce chemical oxygen demand(COD)from 117 to 59 mg/L.The performance of the catalytic ozonation process in the packed-bed reactor for the advanced treatment of actual kitchen wastewater was investigated via both multi-scale simulation and pilot-scale tests in this study,which provided a practical method for optimizing the reactors of treating refractory organic wastewater.

The inactivation of bacteriophages MS2 and PhiX174 by nanoscale zero-valent iron:Resistance difference and mechanisms

Pathogenic enteric viruses pose a significant risk to human health.Nanoscale zero-valent iron(nZVI),a novel material for environmental remediation,has been shown to be a promising tool for disinfection.However,the existing research has typically utilized MS2 or f2 bacteriophages to investigate the antimicrobial properties of nZVI,and the resistance difference between bacteriophages,which is important for the application of disinfection technologies,is not yet understood.Here,MS2 and PhiX174 containing RNA and DNA,respectively,were used as model viruses to investigate the resistances to nZVI.The bacteriophage inactivation mechanisms were also discussed using TEM images,protein,and nucleic acid analysis.The results showed that an initial concentration of 10^(6)PFU/mL of MS2 could be completely inactivated within 240 min by 40 mg/L nZVI at pH 7,whereas the complete inactivation of PhiX174 could not be achieved by extending the reaction time,increasing the nZVI dosage,or changing the dosing means.This indicates that the resistance of phage PhiX174 to nZVI was much stronger than that of MS2.TEM images indicated that the viral particle shape was distorted,and the capsid shell was ruptured by nZVI.The damage to viral surface proteins in both phages was examined by three-dimensional fluorescence spectrum and sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE).However,the nucleic acid analysis demonstrated that the nucleic acid of MS2,but not PhiX174,was destroyed.It indicated that bacteriophage inactivation was mainly attributed to the damage of nucleic acids.

A mini-microbial fuel cell for voltage testing of exoelectrogenic bacteria

Current methods for testing the electricity generation capacity of isolates are time-and laborconsuming.This paper presents a rapid voltage testing system of exoelectrogenic bacteria called Quickscreen,which is based on a microliter microbial fuel cell(MFC).Geobacter sulfurreducens and Shewanella baltica were used as the model exoelectrogenic bacteria;Escherichia coli that cannot generate electricity was used as a negative control.It was found that the electricity generation capacity of the isolates could be determined within about five hours by using Quickscreen,and that its time was relatively rapid compared with the time needed by using larger MFCs.A parallel,stable,and low background voltage was achieved using titanium as a current collector in the blank run.The external resistance had little impact on the blank run during the initial period.The cathode with a five-hole configuration,used to hydrate the carbon cathode,gave higher cathode potential than that with a one-hole configuration.Steady discharge and current interrupt methods showed that the anode mostly contributed to the large internal resistance of the Quickscreen system.However,the addition of graphite felt decreased the resistance from 18 to 5 kΩ.This device was proved to be useful to rapidly evaluate the electricity generation capacity of different bacteria.