Physiological characteristics,geochemical properties and hydrological variables influencing pathogen migration in subsurface system:What we know or not?

The global outbreak of coronavirus infectious disease-2019(COVID-19)draws attentions in the transport and spread of Severe Acute Respiratory Syndrome Coronavirus 2(SARS-CoV-2)in aerosols,wastewater,surface water and solid wastes.As pathogens eventually enter the subsurface system,e.g.,soils in the vadose zone and groundwater in the aquifers,they might survive for a prolonged period of time owing to the uniqueness of subsurface environment.In addition,pathogens can transport in groundwater and contaminate surrounding drinking water sources,possessing long-term and concealed risks to human society.This work critically reviews the influential factors of pathogen migration,unravelling the impacts of pathogenic characteristics,vadose zone physiochemical properties and hydrological variables on the migration of typical pathogens in subsurface system.An assessment algorithm and two rating/weighting schemes are proposed to evaluate the migration abilities and risks of pathogens in subsurface environment.As there is still no evidence about the presence and distribution of SARS-CoV-2 in the vadose zones and aquifers,this study also discusses the migration potential and behavior of SARS-CoV-2 viruses in subsurface environment,offering prospective clues and suggestions for its potential risks in drinking water and effective prevention and control from hydrogeological points of view.

Application of Synthetic Iron Oxyhydroxide with Influencing Factors for Removal of As(Ⅴ) and As(Ⅲ) from Groundwater

Synthesized iron oxyhydroxide was applied for the adsorptive removal of As(V)and As(III)from the aquas media.Additionally,this investigation highlighted the synergistic effect of calcium carbonate in conjunction with iron oxyhydroxide,resulting in enhanced removal efficiency.The experiment was conducted under various conditions:concentration,dosage,pH,agitation,and temperature.Material characterizations such as Brunauer Emmett Teller,X-ray diffraction,scanning electron microscopy,and Fourier transform infrared spectroscopy were implied to understand adsorption mechanisms.The Langmuir model revealed optimal concentrations for As(V)=500μg/L at pH-5 and As(III)=200μg/L at pH-7,resulting in 95%and 93%adsorption efficiencies,respectively.Maximum adsorption capacities“qm”were found to be 1266.943μg/g for As(V)and 1080.241μg/g for As(III).Freundlich model demonstrated favorable adsorption by indicating“n>1”such as As(V)=2.542 and As(III)=2.707;similarly,the speciation factor“RL<1”for both species as As(V)=0.1 and As(III)=0.5,respectively.The kinetic study presented a pseudo-second-order model as best fitted,indicating throughout chemisorption processes for removing As(V)and As(III).Furthermore,incorporating calcium carbonate presented a significant leap in the removal efficiency,indicating As(V)from 95%to 98%and As(III)from 93%to 96%,respectively.Our findings offer profound motivation for developing effective and sustainable solutions to tackle arsenic contamination,underscoring the exceptional promise of iron oxyhydroxide in conjunction with calcium carbonate to achieve maximum removal efficiency.

Arsenic Removal from Groundwater Using Iron Pyrite:Influence Factors and Removal Mechanism

Iron pyrite has been reported as a kind of potential material for arsenic(As)removal from the groundwater because it exhibits a strong attraction in groundwater for both arsenite and arsenate species.In this study,batch adsorption experiments were carried out to determine the optimum conditions for As adsorption by the iron pyrite adsorbent,including the initial concentration,adsorbent dosage ratio,pH,temperature and stirring rate.Precisely characterization methods were employed to identify the mechanism of As removal.Maximum removal efficiency for As(Ⅲ)was observed 93%at pH=7,and for As(Ⅴ)was 95%observed at pH=5.Langmuir model resulted in the maximum adsorption capacity(q_(m))for As(Ⅲ)and As(Ⅴ)were 571.7 and 671.1μg/g,respectively,as well as the experiments were found to be favorable as separation factor R_(L)<1.The value of“n”2.68 and 2.47 for As(Ⅲ)and As(Ⅴ)obtained by Freundlich model(n>1)indicates favorable adsorption.The pseudo-first and second-order kinetic models also fitted well.The addition of oxalate on the adsorbent surface plays an important role for the recycling of Fe(Ⅱ)/Fe(Ⅲ)to minimize the arsenic concentration.Specific surface area,ion exchange mechanism and structure of adsorbent confirmed that addition of oxalate could enhance the surface area of adsorbent.