Environmental Issues Caused by High-Dose Disinfection Need Urgent Attention

Since the end of 2019,the severe acute respiratory syndrome-coronavirus 2(SARS-CoV-2)has spread and infected people all over the world.Up to March 21,2023,more than 760 million people were infected and about 7 million died worldwide(https://covid19.who.int/).In an effort to interrupt the spread of coronavirus disease 2019(COVID-19),high-dose of chlorine-containing disinfectants were utilized in medical institutions and public spaces,including sodium hypochlorite,calcium hypochlorite,chloramine,chlorine dioxide,triclosan,and sodium dichloroisocyanurate.For instance,according to the regulation of the Chinese govern-ment,the effective chlorine dosage is up to 50−80 mg/L for the disinfection of sewage discharged by infectious disease medical diagnosis and treatment institutions receiving COVID-19 patients.

纳米技术在水中病毒灭活中的应用:对新型冠状病毒SARS-CoV-2传播阻断的启示

新型冠状病毒肺炎(COVID-19)疫情给人类社会发展和生命健康造成了巨大威胁,由于新型冠状病毒(SARS-CoV-2)在水中的稳定性,城市污水成为该病毒最集中的污染源之一,因此如何杀灭主要水媒介中的病毒也成为了科学领域关注的重要问题。新冠病毒在结构上由具有遗传效应的RNA链和蛋白衣壳组成,可受活性氧物种(ROS)攻击解体而被灭活。生化代谢的阻断和结构的破坏也是新冠病毒灭活的有效方法。纳米材料因其表面和界面效应、独特的微观结构及优异的物化性质,在新冠病毒杀灭中有很好的应用前景。本文在探讨新型冠状病毒结构组成以及其在水环境中的存活及传播特征的基础上,全面综述了纳米材料在光催化、非均相催化高级氧化、离子毒性灭活和结构效应等方面于灭活病毒中的应用,深入探究了病毒灭活行为及机理。基于此,结合新冠病毒的结构组成及传播特征,深入探讨了不同纳米技术的新冠病毒灭活中的潜在应用。该综述可为环境纳米技术应用于水中新冠病毒灭活及其在水媒介中的次生传播阻断提供理论依据和实践参考。

Fabrication of niobium doped titanate nanoflakes with enhanced visible-light-driven photocatalytic activity for efficient ibuprofen degradation

In this study,a novel class of niobium(Nb) doped titanate nanoflakes(TNFs) are fabricated through a onestep hydrothermal method.Nb doping affects the curving of titanate nanosheet,leading to the formation of nanoflake structure.In addition,Nb5+ filled in the interlayers of [TiO6] alters the light adsorption property of pristine titanate.The band gap of Nb-TNFs is narrowed to 2.85 eV,while neat titanate nano tubes(TNTs) is 3.4 eV.The enhanced visible light adsorption significantly enhances the visible-lightdriven activity of Nb-TNFs for ibuprofen(IBP) degradation.The pseudo-first order kinetics constant for Nb-TNFs is calculated to be 1.04 h^-1,while no obvious removal is observed for TNTs.Photo-generated holes(h^+) and hydroxyl radicals(·OH) are responsible for IBP degradation.The photocatalytic activity of Nb-TNFs depends on pH condition,and the optimal pH value is found to be 5.In addition,Nb-TNFs exhibited superior photo-stability during the reuse cycles.The results demonstrated Nb-TNFs are very promising in photocatalytic water purification.

Active ammonia-oxidizing bacteria and archaea in wastewater treatment systems

Ammonia-oxidizing bacteria(AOB)and archaea(AOA)are two microbial groups mediating nitrification,yet little is presently known about their abundances and community structures at the transcriptional level in wastewater treatment systems(WWTSs).This is a significant issue,as the numerical abundance of AOA or AOB at the gene level may not necessarily represent their functional role in ammonia oxidation.Using amo A genes as molecular markers,this study investigated the transcriptional abundance and community structure of active AOA and AOB in 14 WWTSs.Quantitative PCR results indicated that the transcriptional abundances of AOB amo A(averaged:1.6×10^(8)copies g^(-1)dry sludge)were higher than those of AOA(averaged:3.4×10^(7)copies g^(-1)dry sludge)in all WWTSs despite several higher abundances of AOA amo A at the gene level.Moreover,phylogenetic analysis demonstrated that Nitrosomonas europaea and unknown clusters accounted for 37.66%and 49.96%of the total AOB amo A transcripts,respectively,suggesting their dominant role in driving ammonia oxidation.Meanwhile,AOA amo A transcripts were only successfully retrieved from 3 samples,and the Nitrosospaera sister cluster dominated,accounting for 83.46%.Finally,the substrate utilization kinetics of different AOA and AOB species might play a fundamental role in shaping their niche differentiation,community composition,and functional activity.This study provides a basis for evaluating the relative contributions of ammonia-oxidizing microorganisms(AOMs)to nitrogen conversions in WWTSs.

Metagenomic and viromic data mining reveals viral threats in biologically treated domestic wastewater

Activated sludge(AS),a common biological secondary treatment process in wastewater treatment plants(WWTPs),is known to remove a large spectrum of microorganisms.Yet little is known about its effect on the entire viral community.After compiling 3 Tbp of next-generation sequencing(NGS)metagenomic/viromic datasets consisted of 119 sub-datasets of influent,effluent,and AS samples from 27WWTPs,viral removal efficacy is evaluated through data mining.The normalized abundance of viruses suggests effluents exhibit the highest viral prevalence(3.21±3.26%,n=13)followed by the AS(0.48±0.25%,n=57)and influents(0.23±0.17%,n=17).In contrast,plasmids,representing genetic element of bacteria,show higher average prevalence(0.73±0.82%,n=17)in influents than those of the AS(0.63±0.26%,n=57)and effluents(0.35±0.42%,n=13).Furthermore,the abundance-occupancy analysis identifies 142 core phage viruses and 17 non-phages core viruses,including several pathogenic viruses in the AS virome.The persistent occurrence of pathogenic viruses,coupled with nonfavorable virus removal by the AS treatment,reveals the hidden virus threats in biologically treated domestic wastewater.The mechanisms for why viruses persist and the possibility that WWTPs are potential hotspots for viral survival deserve attention.

Efficient adsorption of europium(Ⅲ)and uranium(Ⅵ)by titanate nanorings:Insights into radioactive metal species

Radioactive wastewater containing high concentration of radionuclides poses severe threats to ecosystem and human health,so efficient removal of these toxic heavy metals is urgently needed.Titanate nanomaterials have been demonstrated good adsorbents for heavy metals due to ion exchange property.In this study,titanate nanorings(TNRs)were synthesized using the facile hydrothermal-cooling method.The TNRs were composed of sodium trititanate,with a chemical formula of Na_(0.66)H_(1.34)-Ti_(3)O_(7)·0.27H_(2)O and a Na content of 2.38 mmol/g.The TNRs demonstrated sufficient adsorption performance to radionuclides europium(Eu)and uranium(U)ions.Specifically,even at a high initial concentration of 50 mg/L,86.5% and 92.6% of the two metal ions can be rapidly adsorbed by the TNRs within 5 min,and equilibrium was reached within 60 min at pH 5.The maximum adsorption capacity(Qmax)obtained by the Langmuir isotherm model was 115.3 mg/g for Eu(Ⅲ)and 282.5 mg/g for uranium U(Ⅵ)at pH 5,respectively.The adsorption capacities of the two metals under various water chemical conditions were highly related to their species.Ion exchange between metal cations and Na^(+) in the TNR interlayers was the dominant adsorption mechanism,and adsorption of U(Ⅵ)was more complicated because of the co-existence of various uranyl(UO_(2)^(2+))and uranyl-hydroxyl species.The spent TNRs were effectively regenerated through an acid-base or ethylenediamine tetraacetic acid(EDTA)treatment and reused.Considering the large adsorption capacity and quick kinetic,TNRs are promising materials to remove radionuclides in environmental purification applications,especially emergent treatment of leaked radionuclides.

A review on treatment of disinfection byproduct precursors by biological activated carbon process

Disinfection by-products(DBPs)in water systems have attracted increasing attention due to their toxic effects.Removal of precursors(mainly natural organic matter(NOM))prior to the disinfection process has been recognized as the ideal strategy to control the DBP levels.Currently,biological activated carbon(BAC)process is a highly recommended and prevalent process for treatment of DBP precursors in advanced water treatment.This paper first introduces the fundamental knowledge of BAC process,including the history,basic principles,typical process flow,and basic operational parameters.Then,the selection of BAC process for treatment of DBP precursors is explained in detail based on the comparative analysis of dominant water treatment technologies from the aspects of mechanisms for NOM removal as well as the treatability of different groups of DBP precursors.Next,a thorough overview is presented to summarize the recent developments and breakthroughs in the removal of DBP precursors using BAC process,and the contents involved include effect of pre-BAC ozonation,removal performance of various DBP precursors,toxicity risk reduction,fractional analysis of NOM,effect of empty bed contact time(EBCT)and engineered biofiltration.Finally,some recommendations are made to strengthen current research and address the knowledge gaps,including the issues of microbial mechanisms,toxicity evaluation,degradation kinetics and microbial products.