BACKGROUND Ulcerative colitis(UC)with concomitant primary sclerosing cholangitis(PSC)represents a distinct disease entity(PSC-UC).Mayo endoscopic subscore(MES)is a standard tool for assessing disease activity in UC bu...BACKGROUND Ulcerative colitis(UC)with concomitant primary sclerosing cholangitis(PSC)represents a distinct disease entity(PSC-UC).Mayo endoscopic subscore(MES)is a standard tool for assessing disease activity in UC but its relevance in PSC-UC remains unclear.AIM To assess the accuracy of MES in UC and PSC-UC patients,we performed histological scoring using Nancy histological index(NHI).METHODS MES was assessed in 30 PSC-UC and 29 UC adult patients during endoscopy.NHI and inflammation were evaluated in biopsies from the cecum,rectum,and terminal ileum.In addition,perinuclear anti-neutrophil cytoplasmic antibodies,fecal calprotectin,body mass index,and other relevant clinical characteristics were collected.RESULTS The median MES and NHI were similar for UC patients(MES grade 2 and NHI grade 2 in the rectum)but were different for PSC-UC patients(MES grade 0 and NHI grade 2 in the cecum).There was a correlation between MES and NHI for UC patients(Spearman's r=0.40,P=0.029)but not for PSC-UC patients.Histopathological examination revealed persistent microscopic inflammation in 88%of PSC-UC patients with MES grade 0(46%of all PSC-UC patients).Moreover,MES overestimated the severity of active inflammation in an additional 11%of PSCUC patients.CONCLUSION MES insufficiently identifies microscopic inflammation in PSC-UC.This indicates that histological evaluation should become a routine procedure of the diagnostic and grading system in both PSC-UC and PSC.展开更多
This paper presents an optimization approach—residual-based bootstrap averaging(RBBA)—for different types of forecast ensembles.Unlike traditional residual-mean-square-error-based ensemble forecast averaging approac...This paper presents an optimization approach—residual-based bootstrap averaging(RBBA)—for different types of forecast ensembles.Unlike traditional residual-mean-square-error-based ensemble forecast averaging approaches,the RBBA method attempts to find optimal forecast weights in an ensemble and allows for their combi-nation into the most effective additive forecast.In the RBBA method,all the different types of forecasts obtain the optimal weights for ensemble residuals that are statisti-cally optimal in terms of the fitness function of the residuals.Empirical studies have been conducted to demonstrate why and how the RBBA method works.The experi-mental results based on the real-world time series of contemporary stock exchanges show that the RBBA method can produce ensemble forecasts with good generalization ability.展开更多
The digital twins concept enhances modeling and simulation through the integration of real-time data and feedback.This review elucidates the foundational elements of digital twins,covering their concept,entities,domai...The digital twins concept enhances modeling and simulation through the integration of real-time data and feedback.This review elucidates the foundational elements of digital twins,covering their concept,entities,domains,and key technologies.More specifically,we investigate the transformative potential of digital twins for the wastewater treatment engineering sector.Our discussion highlights the application of digital twins to wastewater treatment plants(WWTPs)and sewage networks,hardware(i.e.,facilities and pipes,sensors for water quality and activated sludge,hydrodynamics,and power consumption),and software(i.e.,knowledge-based and data-driven models,mechanistic models,hybrid twins,control methods,and the Internet of Things).Furthermore,two cases are provided,followed by an assessment of current challenges in and perspectives on the application of digital twins in WWTPs.This review serves as an essential primer for wastewater engineers navigating the digital paradigm shift.展开更多
OBJECTIVE:To systematically investigate the clinical effectiveness and safety of traditional Chinese herbs(TCHs)as an alternative to conventional medicine(CM)in children with cough variant asthma(CVA).METHODS:Randomiz...OBJECTIVE:To systematically investigate the clinical effectiveness and safety of traditional Chinese herbs(TCHs)as an alternative to conventional medicine(CM)in children with cough variant asthma(CVA).METHODS:Randomized controlled trial(RCT)studies that were published from their inceptions to March 31,2020,were identified from the electronic databases of China National Knowledge Infrastructure,Wangfang,Pub Med,and Cochrane Central Library.The primary outcome of the review was the total effective rate(TER),and the secondary outcomes were immunoglobulin E(Ig E),peak expiratory flow(PEF),adverse drug reactions,and relapse rates of interventions.RESULTS:For the Meta-analysis,13 studies involving 992 children with CVA were included.In terms of TER and Ig E,the experimental interventions of TCH,when compared with the control interventions of CM,on pediatric CVA were found to be significantly effective(P<0.0001),whereas for spirometry,PEF was not significantly improved in the TCH group(P=0.48).The incident rates of adverse drug reaction and relapse were found to be significantly lower in the TCH group than those in the CM group(P=0.02 and P<0.0001,respectively).CONCLUSION:Compared with CM therapy,the effects of TCH therapy on pediatric CVA were significantly beneficial in terms of TER and Ig E,but not for PEF,and the methodological quality of included studies was poor.Therefore,the results should be interpreted with caution.More randomized controlled trials with rigorous experimental methodologies are required for objectivity in the future.展开更多
BACKGROUND Psychosocial and physical trauma are known risk factors for irritable bowel syndrome(IBS),including in war veterans,whereas war exposure in civilians is unclear.Nicaragua experienced two wars,1970-1990:The ...BACKGROUND Psychosocial and physical trauma are known risk factors for irritable bowel syndrome(IBS),including in war veterans,whereas war exposure in civilians is unclear.Nicaragua experienced two wars,1970-1990:The Sandinistas Revolution(1970s)and The Contra War(1980s).Our aim was to investigate the role of exposure to war trauma in the subsequent development of IBS in the context of an established health surveillance system(11000 households).AIM To investigate in a civilian population the relationship between exposure to war trauma and events and the subsequent development of IBS in the context of an established public health and demographic surveillance system in western Nicaragua.METHODS We conducted a nested population-based,cross-sectional study focused on functional gastrointestinal disorders based on Rome II criteria.1617 adults were randomly selected.The Spanish Rome II Modular Questionnaire and Harvard Trauma Questionnaire were validated in Nicaragua.War exposure was assessed with 10 measures of direct and indirect war trauma and post-war effects.Multiple exposures were defined by≥3 measures.RESULTS The prevalence of IBS was 15.2%[Female(F)17.1%,Male(M)12.0%],war exposure 19.3%(F 9.3%,M 36.7%),and post-traumatic stress disorder(PTSD)5.6%(F 6.4%,M 4.3%).Significant associations with IBS in the civilian population were observed(adjusted by gender,age,socioeconomic status,education):physical and psychological abuse[adjusted odds ratio(aOR):2.25;95%confidence interval:1.1-4.5],witnessed execution(aOR:2.4;1.1-5.2),family member death(aOR:2.2;1.2-4.2),and multiple exposures(aOR:2.7;1.4-5.1).PTSD was independently associated with IBS(aOR:2.6;1.2-5.7).CONCLUSION An enduring association was observed in the Nicaragua civilian population between specific civil war-related events and subsequent IBS.Civilian populations in regions with extended armed conflict may warrant provider education and targeted interventions for patients.展开更多
An intersection of two or more roads poses a risk for potential conflicts among vehicles.Often the reasons triggering such conflicts are not clear,as they might be too subtle for the human eye.The environment also pla...An intersection of two or more roads poses a risk for potential conflicts among vehicles.Often the reasons triggering such conflicts are not clear,as they might be too subtle for the human eye.The environment also plays a part in understanding where,when,and why a particular vehicle interaction has occurred in a certain way.Therefore,it is of paramount importance to dive deeper into the vehicle interaction at a micro-scale within the embedded geographical environment,particularly at the intersections.This would in turn assist in evaluating the association of vehicle interactions with conflict risks and near-miss accidents.Moreover,detection of such micro traffic interactions could also be used to improvise the complexity of the already established transport infrastructure.Conversely,traffic at intersections has been explored mainly for flow estimation,capacity and width measurements,and traffic congestion,etc.,whereas the detection of micro-scale traffic interactions at intersections remains relatively under-explored.In this paper,we present a novel approach to retrieve and represent micro-scale traffic movement interactions at a non-signalized T-junction by extending a recently introduced qualitative spatiotemporal Point-Descriptor-Precedence(PDP)representation.We study how the PDP representation offers a fine solution to study the interaction of traffic flows at intersections.This permits tracking the micro-movement of vehicles in much finer detail,which is used later to retrieve movement patterns from a motion dataset.Unlike conventional approaches,we start our approach with the actual movements before modeling the static intersection environment.Additionally,with the aid of illustrative examples,we discuss how the length,width,and speed of the vehicles can be exploited in our approach to detect specific patterns more accurately.Additionally,we address the potential benefits of our approach for traffic safety assessment and how it can be extended to a network of intersections using different transport modes.展开更多
Further treatment of secondary effluents before their discharge into the receiving water bodies could alleviate water eutrophication.In this study,the Chlorella proteinosa was cultured in a membrane photobioreactor to...Further treatment of secondary effluents before their discharge into the receiving water bodies could alleviate water eutrophication.In this study,the Chlorella proteinosa was cultured in a membrane photobioreactor to further remove nitrogen from the secondary effluents.The effect of hydraulic retention time(HRT)on microalgae biomass yields and nutrient removal was studied.The results showed that soluble algal products concentration reduced in the suspension at low HRT,thereby alleviating microalgal growth inhibition.In addition,the lower HRT reduced the nitrogen limitation for Chlorella proteinosa’s growth through the phase-out of nitrogen-related functional bacteria.As a result,the productivity for Chlorella proteinosa increased from 6.12 mg/L/day at an HRT of 24 hr to 20.18 mg/L/day at an HRT of 8 hr.The highest removal rates of 19.7 mg/L/day,23.8 mg/L/day,and 105.4 mg/L/day were achieved at an HRT of 8 hr for total nitrogen(TN),ammonia,and chemical oxygen demand(COD),respectively.However,in terms of removal rate,TN and COD were the largest when HRT is 24 hr,which were 74.5%and 82.6%respectively.The maximum removal rate of ammonia nitrogen was 99.2%when HRT was 8 hr.展开更多
Water management in most of the developed world is currently practiced in a highly centralized manner,leading to major infrastructure and energy costs to transport water.To decrease the impacts of water scarcity and c...Water management in most of the developed world is currently practiced in a highly centralized manner,leading to major infrastructure and energy costs to transport water.To decrease the impacts of water scarcity and climate change,the decentralization of water can increase local robustness.In extremis,decentralization can involve building or house level water supply and treatment.Here,we constructed a MATLAB/Simulink model for two decentralized water management configurations at the household level,assuming the socio-environmental setting of Flanders,Belgium.Independence from the potable water grid and sewer system was pursued through rainwater harvesting,reuse of wastewater streams fitfor-purpose,and discharge via infiltration.The mass balance for water was calculated over the system boundaries showing high potential for independence from the grid with a reasonable treatment train and storage options.Next,the risk of contaminant accumulation within the circular system was assessed,showing a key limitation on decentralized system performance necessitating a system purge.Up to 59%of system rainwater usage was due to the replacement of this purge.Employing treatment units with high(95%)contaminant rejection efficiencies eliminated contaminant accumulation issues.The raw model output was quantitatively assessed by constructing four newly proposed key performance indicators(KPIs),quantifying system independence,circularity,drought tolerance and local water body recharge,which allowed for facilitated system comparison and communication to stakeholders.A sensitivity analysis was performed in which the effect of input parameter variability and uncertainty on system performance was quantified.The sensitivity analysis showed the importance of water recovery and contaminant removal efficiencies of the applied treatment technologies on system performance when contaminant accumulation in the system forms an issue.In systems not severely affected by pollutant accumulation,parameters such as inhabitant number and roof surface had the largest effect.As a whole,this work shows the potential of extreme decentralization of water systems and addresses the obstacle towards implementation formed by the accumulation of contaminants due to system circularity.Additionally,this study provides a framework for operational and technological decision support of decentralized household-scale water systems and,by extension,for future water policy-making.展开更多
Mainstream partial nitritation-anammox(PNA)process easily suffers from performance instability and even reactor collapse in application.Thus,it is of great significance to unveil the characteristic of performance reco...Mainstream partial nitritation-anammox(PNA)process easily suffers from performance instability and even reactor collapse in application.Thus,it is of great significance to unveil the characteristic of performance recovery,understand the intrinsic mechanism and then propose operational strategy.In this study,we combined long-term reactor operation,batch tests,and metagenomics to reveal the succession of microbial community and functional metabolism variation from system collapse to recovery.Proper aeration control(0.10-0.25mg O_(2)/L)was critical for performance recovery.It was also found that Candidatus Brocadia became the dominant flora and its abundance increased from 3.5%to 11.0%.Significant enhancements in carbon metabolism and phospholipid biosynthesis were observed during system recovery,and the genes abundance related to signal transduction was dramatically increased.The up-regulation of sdh and suc genes showed the processes of succinate dehydrogenation and succinyl-CoA synthesis might stimulate the production of amino acids and the synthesis of proteins,thereby possibly improving the activity and abundance of AnAOB,which was conducive to the performance recovery.Moreover,the increase in abundance of hzs and hdh genes suggested the enhancement of the anammox process.Changes in the abundance of key genes involved in nitrogen metabolism indicated that nitrogen removal pathway was more diverse after system recovery.The achievement of performance recovery was driven by anammox,nitrification and denitrification coupled with dissimilatory nitrate reduction to ammonium.These results provide deeper insights into the recovery mechanism of PNA system and also provide a potential regulation strategy for the stable operation of the mainstream PNA process.展开更多
基金Supported by Grant Agency of the Ministry of Health of the Czech Republic,No.NV17-31538AGrant Agency of the Czech Republic No.20-16520Y and No.21-21736SMinistry of Education,Youth and Sports of the Czech Republic Project,No.LX22NPO05102.
文摘BACKGROUND Ulcerative colitis(UC)with concomitant primary sclerosing cholangitis(PSC)represents a distinct disease entity(PSC-UC).Mayo endoscopic subscore(MES)is a standard tool for assessing disease activity in UC but its relevance in PSC-UC remains unclear.AIM To assess the accuracy of MES in UC and PSC-UC patients,we performed histological scoring using Nancy histological index(NHI).METHODS MES was assessed in 30 PSC-UC and 29 UC adult patients during endoscopy.NHI and inflammation were evaluated in biopsies from the cecum,rectum,and terminal ileum.In addition,perinuclear anti-neutrophil cytoplasmic antibodies,fecal calprotectin,body mass index,and other relevant clinical characteristics were collected.RESULTS The median MES and NHI were similar for UC patients(MES grade 2 and NHI grade 2 in the rectum)but were different for PSC-UC patients(MES grade 0 and NHI grade 2 in the cecum).There was a correlation between MES and NHI for UC patients(Spearman's r=0.40,P=0.029)but not for PSC-UC patients.Histopathological examination revealed persistent microscopic inflammation in 88%of PSC-UC patients with MES grade 0(46%of all PSC-UC patients).Moreover,MES overestimated the severity of active inflammation in an additional 11%of PSCUC patients.CONCLUSION MES insufficiently identifies microscopic inflammation in PSC-UC.This indicates that histological evaluation should become a routine procedure of the diagnostic and grading system in both PSC-UC and PSC.
文摘This paper presents an optimization approach—residual-based bootstrap averaging(RBBA)—for different types of forecast ensembles.Unlike traditional residual-mean-square-error-based ensemble forecast averaging approaches,the RBBA method attempts to find optimal forecast weights in an ensemble and allows for their combi-nation into the most effective additive forecast.In the RBBA method,all the different types of forecasts obtain the optimal weights for ensemble residuals that are statisti-cally optimal in terms of the fitness function of the residuals.Empirical studies have been conducted to demonstrate why and how the RBBA method works.The experi-mental results based on the real-world time series of contemporary stock exchanges show that the RBBA method can produce ensemble forecasts with good generalization ability.
基金supported by the National Natural Science Foundation of China(52321005,52293443,and 52230004)the Shenzhen Science and Technology Program(KQTD20190929172630447)+1 种基金the Shenzhen Key Research Project(GXWD20220817145054002)the Talent Recruitment Project of Guandong(2021QN020106).
文摘The digital twins concept enhances modeling and simulation through the integration of real-time data and feedback.This review elucidates the foundational elements of digital twins,covering their concept,entities,domains,and key technologies.More specifically,we investigate the transformative potential of digital twins for the wastewater treatment engineering sector.Our discussion highlights the application of digital twins to wastewater treatment plants(WWTPs)and sewage networks,hardware(i.e.,facilities and pipes,sensors for water quality and activated sludge,hydrodynamics,and power consumption),and software(i.e.,knowledge-based and data-driven models,mechanistic models,hybrid twins,control methods,and the Internet of Things).Furthermore,two cases are provided,followed by an assessment of current challenges in and perspectives on the application of digital twins in WWTPs.This review serves as an essential primer for wastewater engineers navigating the digital paradigm shift.
文摘OBJECTIVE:To systematically investigate the clinical effectiveness and safety of traditional Chinese herbs(TCHs)as an alternative to conventional medicine(CM)in children with cough variant asthma(CVA).METHODS:Randomized controlled trial(RCT)studies that were published from their inceptions to March 31,2020,were identified from the electronic databases of China National Knowledge Infrastructure,Wangfang,Pub Med,and Cochrane Central Library.The primary outcome of the review was the total effective rate(TER),and the secondary outcomes were immunoglobulin E(Ig E),peak expiratory flow(PEF),adverse drug reactions,and relapse rates of interventions.RESULTS:For the Meta-analysis,13 studies involving 992 children with CVA were included.In terms of TER and Ig E,the experimental interventions of TCH,when compared with the control interventions of CM,on pediatric CVA were found to be significantly effective(P<0.0001),whereas for spirometry,PEF was not significantly improved in the TCH group(P=0.48).The incident rates of adverse drug reaction and relapse were found to be significantly lower in the TCH group than those in the CM group(P=0.02 and P<0.0001,respectively).CONCLUSION:Compared with CM therapy,the effects of TCH therapy on pediatric CVA were significantly beneficial in terms of TER and Ig E,but not for PEF,and the methodological quality of included studies was poor.Therefore,the results should be interpreted with caution.More randomized controlled trials with rigorous experimental methodologies are required for objectivity in the future.
基金Supported by the UNC UNAN FGID Epidemiology Study Project,No.54-1808958.
文摘BACKGROUND Psychosocial and physical trauma are known risk factors for irritable bowel syndrome(IBS),including in war veterans,whereas war exposure in civilians is unclear.Nicaragua experienced two wars,1970-1990:The Sandinistas Revolution(1970s)and The Contra War(1980s).Our aim was to investigate the role of exposure to war trauma in the subsequent development of IBS in the context of an established health surveillance system(11000 households).AIM To investigate in a civilian population the relationship between exposure to war trauma and events and the subsequent development of IBS in the context of an established public health and demographic surveillance system in western Nicaragua.METHODS We conducted a nested population-based,cross-sectional study focused on functional gastrointestinal disorders based on Rome II criteria.1617 adults were randomly selected.The Spanish Rome II Modular Questionnaire and Harvard Trauma Questionnaire were validated in Nicaragua.War exposure was assessed with 10 measures of direct and indirect war trauma and post-war effects.Multiple exposures were defined by≥3 measures.RESULTS The prevalence of IBS was 15.2%[Female(F)17.1%,Male(M)12.0%],war exposure 19.3%(F 9.3%,M 36.7%),and post-traumatic stress disorder(PTSD)5.6%(F 6.4%,M 4.3%).Significant associations with IBS in the civilian population were observed(adjusted by gender,age,socioeconomic status,education):physical and psychological abuse[adjusted odds ratio(aOR):2.25;95%confidence interval:1.1-4.5],witnessed execution(aOR:2.4;1.1-5.2),family member death(aOR:2.2;1.2-4.2),and multiple exposures(aOR:2.7;1.4-5.1).PTSD was independently associated with IBS(aOR:2.6;1.2-5.7).CONCLUSION An enduring association was observed in the Nicaragua civilian population between specific civil war-related events and subsequent IBS.Civilian populations in regions with extended armed conflict may warrant provider education and targeted interventions for patients.
基金supported by the Higher Education Commission(HEC),Pakistan[grant number 50040696]Bernard De Baets and Guy De Tréreceived funding from the Flemish Government under the“Onderzoeksprogramma Artificiële Intelligentie(AI)Vlaanderen”program.
文摘An intersection of two or more roads poses a risk for potential conflicts among vehicles.Often the reasons triggering such conflicts are not clear,as they might be too subtle for the human eye.The environment also plays a part in understanding where,when,and why a particular vehicle interaction has occurred in a certain way.Therefore,it is of paramount importance to dive deeper into the vehicle interaction at a micro-scale within the embedded geographical environment,particularly at the intersections.This would in turn assist in evaluating the association of vehicle interactions with conflict risks and near-miss accidents.Moreover,detection of such micro traffic interactions could also be used to improvise the complexity of the already established transport infrastructure.Conversely,traffic at intersections has been explored mainly for flow estimation,capacity and width measurements,and traffic congestion,etc.,whereas the detection of micro-scale traffic interactions at intersections remains relatively under-explored.In this paper,we present a novel approach to retrieve and represent micro-scale traffic movement interactions at a non-signalized T-junction by extending a recently introduced qualitative spatiotemporal Point-Descriptor-Precedence(PDP)representation.We study how the PDP representation offers a fine solution to study the interaction of traffic flows at intersections.This permits tracking the micro-movement of vehicles in much finer detail,which is used later to retrieve movement patterns from a motion dataset.Unlike conventional approaches,we start our approach with the actual movements before modeling the static intersection environment.Additionally,with the aid of illustrative examples,we discuss how the length,width,and speed of the vehicles can be exploited in our approach to detect specific patterns more accurately.Additionally,we address the potential benefits of our approach for traffic safety assessment and how it can be extended to a network of intersections using different transport modes.
基金supported by the China Hunan Provincial Science&Technology Department(Nos.2022SK2091 and 2019JJ50646)the Hunan Provincial Department of Education(Nos.18C0206 and 19B040).
文摘Further treatment of secondary effluents before their discharge into the receiving water bodies could alleviate water eutrophication.In this study,the Chlorella proteinosa was cultured in a membrane photobioreactor to further remove nitrogen from the secondary effluents.The effect of hydraulic retention time(HRT)on microalgae biomass yields and nutrient removal was studied.The results showed that soluble algal products concentration reduced in the suspension at low HRT,thereby alleviating microalgal growth inhibition.In addition,the lower HRT reduced the nitrogen limitation for Chlorella proteinosa’s growth through the phase-out of nitrogen-related functional bacteria.As a result,the productivity for Chlorella proteinosa increased from 6.12 mg/L/day at an HRT of 24 hr to 20.18 mg/L/day at an HRT of 8 hr.The highest removal rates of 19.7 mg/L/day,23.8 mg/L/day,and 105.4 mg/L/day were achieved at an HRT of 8 hr for total nitrogen(TN),ammonia,and chemical oxygen demand(COD),respectively.However,in terms of removal rate,TN and COD were the largest when HRT is 24 hr,which were 74.5%and 82.6%respectively.The maximum removal rate of ammonia nitrogen was 99.2%when HRT was 8 hr.
文摘Water management in most of the developed world is currently practiced in a highly centralized manner,leading to major infrastructure and energy costs to transport water.To decrease the impacts of water scarcity and climate change,the decentralization of water can increase local robustness.In extremis,decentralization can involve building or house level water supply and treatment.Here,we constructed a MATLAB/Simulink model for two decentralized water management configurations at the household level,assuming the socio-environmental setting of Flanders,Belgium.Independence from the potable water grid and sewer system was pursued through rainwater harvesting,reuse of wastewater streams fitfor-purpose,and discharge via infiltration.The mass balance for water was calculated over the system boundaries showing high potential for independence from the grid with a reasonable treatment train and storage options.Next,the risk of contaminant accumulation within the circular system was assessed,showing a key limitation on decentralized system performance necessitating a system purge.Up to 59%of system rainwater usage was due to the replacement of this purge.Employing treatment units with high(95%)contaminant rejection efficiencies eliminated contaminant accumulation issues.The raw model output was quantitatively assessed by constructing four newly proposed key performance indicators(KPIs),quantifying system independence,circularity,drought tolerance and local water body recharge,which allowed for facilitated system comparison and communication to stakeholders.A sensitivity analysis was performed in which the effect of input parameter variability and uncertainty on system performance was quantified.The sensitivity analysis showed the importance of water recovery and contaminant removal efficiencies of the applied treatment technologies on system performance when contaminant accumulation in the system forms an issue.In systems not severely affected by pollutant accumulation,parameters such as inhabitant number and roof surface had the largest effect.As a whole,this work shows the potential of extreme decentralization of water systems and addresses the obstacle towards implementation formed by the accumulation of contaminants due to system circularity.Additionally,this study provides a framework for operational and technological decision support of decentralized household-scale water systems and,by extension,for future water policy-making.
基金supported by the National Key Research and Development Program of China (No.2021YFC3201504)the National Natural Science Foundations of China (No.52000140)the Social Development Program of Science and Technology Committee Foundations of Shanghai (No.22dz1209200)。
文摘Mainstream partial nitritation-anammox(PNA)process easily suffers from performance instability and even reactor collapse in application.Thus,it is of great significance to unveil the characteristic of performance recovery,understand the intrinsic mechanism and then propose operational strategy.In this study,we combined long-term reactor operation,batch tests,and metagenomics to reveal the succession of microbial community and functional metabolism variation from system collapse to recovery.Proper aeration control(0.10-0.25mg O_(2)/L)was critical for performance recovery.It was also found that Candidatus Brocadia became the dominant flora and its abundance increased from 3.5%to 11.0%.Significant enhancements in carbon metabolism and phospholipid biosynthesis were observed during system recovery,and the genes abundance related to signal transduction was dramatically increased.The up-regulation of sdh and suc genes showed the processes of succinate dehydrogenation and succinyl-CoA synthesis might stimulate the production of amino acids and the synthesis of proteins,thereby possibly improving the activity and abundance of AnAOB,which was conducive to the performance recovery.Moreover,the increase in abundance of hzs and hdh genes suggested the enhancement of the anammox process.Changes in the abundance of key genes involved in nitrogen metabolism indicated that nitrogen removal pathway was more diverse after system recovery.The achievement of performance recovery was driven by anammox,nitrification and denitrification coupled with dissimilatory nitrate reduction to ammonium.These results provide deeper insights into the recovery mechanism of PNA system and also provide a potential regulation strategy for the stable operation of the mainstream PNA process.
