This study evaluates the performance of small-scale high-temperature treatment facilities for managing rural domestic waste on the Tibetan Plateau and investigates the emission characteristics of dioxin pollutants.Sev...This study evaluates the performance of small-scale high-temperature treatment facilities for managing rural domestic waste on the Tibetan Plateau and investigates the emission characteristics of dioxin pollutants.Seven small-scale facilities(with capacities ranging from 3 to 25 t/d)selected from a total of 183 different facilities in the Tibetan Plateau region,underwent on-site sampling and laboratory multi-threaded pollutant analysis of pollutants.The results revealed that dioxin emission concentrations in the flue gas ranged from 0.085 to 53.6 ng I-TEQ/Nm3.The primary mechanism for dioxin synthesis in the flue gas of small-scale gasification incinerators and high-temperature pyrolysis furnaces consisted of the precursor formation mechanism,whereas de novo synthesis was observed in conventional incinerators.Dioxin concentrations in fly ash varied from 0.0060 to 11.59 ng I-TEQ/g,with precursor synthesis as the dominant pathway.The distribution of dioxin in activated carbon and desulfurization lye notably differed significantly from that in the flue gas and fly ash congeners.Additionally,the dioxin content in the pyrolysis products exceeded both the concentrations in purchased-coal and the relevant emission limits.The total emission factors for these facilities ranged from 0.49 to 326.92μg I-TEQ/t,with variations of the distribution of dioxin emission factors observed across different facilities.展开更多
The distribution of antibiotic resistance genes(ARGs)has been intensively studied in large-scale wastewater treatment plants and livestock sources.However,small-scale decentralized sewage treatment facilities must als...The distribution of antibiotic resistance genes(ARGs)has been intensively studied in large-scale wastewater treatment plants and livestock sources.However,small-scale decentralized sewage treatment facilities must also be explored due to their possible direct exposure to residents.In this study,six wastewater treatment facilities in developed rural areas in eastern China were investigated to understand their risks of spreading ARGs.Using metagenomics and network analysis tools,ARGs and bacterial and viral communities were identified in the influent(INF)and effluent(EFF)samples.The dominant ARGs belonged to the bacitracin class,which are different from most of municipal wastewater treatment plants(WWTPs).The dominant hosts of ARGs are Acidovorax in bacterial communities and Prymnesiovirus in viral communities.Furthermore,a positive relationship was found between ARGs and phages.The ARGs significantly correlated with phages were all hosted by specific genera of bacteria,indicating that phages had contributed to the ARG’s proliferation in sewage treatment facilities.Paying significant concern on the possible enhanced risks caused by bacteria,viruses and their related ARGs in decentralized sewage treatment facilities is necessary.展开更多
The increasing application of anammox processes suggests their enormous potential for nitrogen removal in wastewater treatment facilities.However,the functional potentials and ecological differentiation of cooccurring...The increasing application of anammox processes suggests their enormous potential for nitrogen removal in wastewater treatment facilities.However,the functional potentials and ecological differentiation of cooccurring anammox species in complex ecosystems have not been well elucidated.Herein,by utilizing functional reconstruction and comparative genome analysis,we deciphered the cooccurring mechanisms of four Candidatus Brocadia species that were spontaneously enriched in a full-scale swine wastewater treatment system.Phylogenetic analysis indicated that species SW172 and SW745 were closely related to Ca.Brocadia caroliniensis and Ca.Brocadia sapporoensis,respectively,whereas the dominant species SW510 and SW773,with a total average abundance of 34.1%,were classified as novel species of the genus Ca.Brocadia.Functional reconstruction revealed that the novel species SW510 can encode both cytochrome cd1-type nitrite reductase and hydroxylamine oxidase for nitrite reduction.In contrast,the detected respiratory pentaheme cytochrome c nitrite reductase and acetate kinase genes suggested that SW773 likely reduced nitrite to ammonium with acetate as a carbon source.Intriguingly,the presence of genes encoding urease and cyanase indicated that both novel species can use diverse organic nitrogen compounds in addition to ammonia and nitrite as substrates.Taken together,the recovery and comparative analysis of these anammox genomes expand our understanding of the functional differentiation and cooccurrence of the genus Ca.Brocadia in wastewater treatment systems.展开更多
Bioaerosol emissions from wastewater and wastewater treatment processes are a significant subgroup of atmospheric aerosols. Most previous work has focused on the evaluation of their biological risks. In this study, ho...Bioaerosol emissions from wastewater and wastewater treatment processes are a significant subgroup of atmospheric aerosols. Most previous work has focused on the evaluation of their biological risks. In this study, however, the adsorption method was applied to reduce airborne microorganisms generated from a pilot scale wastewater treatment facility with oxidation ditch. Results showed adsorption on granule activated carbon （GAC） was an efficient method for the purification of airborne microorganisms. The GAC itself had a maximum adsorption capacity of 2217 CFU/g for airborne bacteria and 225 CFU/g for fungi with a flow rate of 1.50 m^3/hr. Over 85% of airborne bacteria and fungi emitted from the oxidation ditch were adsorbed within 80 hr of continuous operation mode. Most of them had a particle size of 0.65-4.7 μm. Those airborne microorganisms with small particle size were apt to be adsorbed. The SEM/EDAX, BET and Boehm＇s titration methods were applied to analyse the physicochemical characteristics of the GAC. Relationships between GAC surface characteristics and its adsorption performance demonstrated that porous structure, large surface area, and hydrophobicity rendered GAC an effective absorber of airborne microorganisms. Two regenerate methods, ultraviolet irradiation and high pressure vapor, were compared for the regeneration of used activated carbon. High pressure vapor was an effective technique as it totally destroyed the microorganisms adhered to the activated carbon. Microscopic observation was also carried out to investigate original and used adsorbents.展开更多
文摘This study evaluates the performance of small-scale high-temperature treatment facilities for managing rural domestic waste on the Tibetan Plateau and investigates the emission characteristics of dioxin pollutants.Seven small-scale facilities(with capacities ranging from 3 to 25 t/d)selected from a total of 183 different facilities in the Tibetan Plateau region,underwent on-site sampling and laboratory multi-threaded pollutant analysis of pollutants.The results revealed that dioxin emission concentrations in the flue gas ranged from 0.085 to 53.6 ng I-TEQ/Nm3.The primary mechanism for dioxin synthesis in the flue gas of small-scale gasification incinerators and high-temperature pyrolysis furnaces consisted of the precursor formation mechanism,whereas de novo synthesis was observed in conventional incinerators.Dioxin concentrations in fly ash varied from 0.0060 to 11.59 ng I-TEQ/g,with precursor synthesis as the dominant pathway.The distribution of dioxin in activated carbon and desulfurization lye notably differed significantly from that in the flue gas and fly ash congeners.Additionally,the dioxin content in the pyrolysis products exceeded both the concentrations in purchased-coal and the relevant emission limits.The total emission factors for these facilities ranged from 0.49 to 326.92μg I-TEQ/t,with variations of the distribution of dioxin emission factors observed across different facilities.
基金supported by the Major Science and Technology Program for Water Pollution Control and Treatment(2017ZX07202-003)National Natural Science Foundation of China(51778325)+1 种基金the Fundamental Research Fund for the Central Universities(FRF-TP-20-011A)the Research Fund Program of Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology(2020B 1212060022).
文摘The distribution of antibiotic resistance genes(ARGs)has been intensively studied in large-scale wastewater treatment plants and livestock sources.However,small-scale decentralized sewage treatment facilities must also be explored due to their possible direct exposure to residents.In this study,six wastewater treatment facilities in developed rural areas in eastern China were investigated to understand their risks of spreading ARGs.Using metagenomics and network analysis tools,ARGs and bacterial and viral communities were identified in the influent(INF)and effluent(EFF)samples.The dominant ARGs belonged to the bacitracin class,which are different from most of municipal wastewater treatment plants(WWTPs).The dominant hosts of ARGs are Acidovorax in bacterial communities and Prymnesiovirus in viral communities.Furthermore,a positive relationship was found between ARGs and phages.The ARGs significantly correlated with phages were all hosted by specific genera of bacteria,indicating that phages had contributed to the ARG’s proliferation in sewage treatment facilities.Paying significant concern on the possible enhanced risks caused by bacteria,viruses and their related ARGs in decentralized sewage treatment facilities is necessary.
基金supported by the National Natural Science Foundation of China(Nos.52000185,51878675,and 51622813)the Natural Science Foundation of Guangdong Province(No.2021A1515010512)the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(No.2021qntd07).
文摘The increasing application of anammox processes suggests their enormous potential for nitrogen removal in wastewater treatment facilities.However,the functional potentials and ecological differentiation of cooccurring anammox species in complex ecosystems have not been well elucidated.Herein,by utilizing functional reconstruction and comparative genome analysis,we deciphered the cooccurring mechanisms of four Candidatus Brocadia species that were spontaneously enriched in a full-scale swine wastewater treatment system.Phylogenetic analysis indicated that species SW172 and SW745 were closely related to Ca.Brocadia caroliniensis and Ca.Brocadia sapporoensis,respectively,whereas the dominant species SW510 and SW773,with a total average abundance of 34.1%,were classified as novel species of the genus Ca.Brocadia.Functional reconstruction revealed that the novel species SW510 can encode both cytochrome cd1-type nitrite reductase and hydroxylamine oxidase for nitrite reduction.In contrast,the detected respiratory pentaheme cytochrome c nitrite reductase and acetate kinase genes suggested that SW773 likely reduced nitrite to ammonium with acetate as a carbon source.Intriguingly,the presence of genes encoding urease and cyanase indicated that both novel species can use diverse organic nitrogen compounds in addition to ammonia and nitrite as substrates.Taken together,the recovery and comparative analysis of these anammox genomes expand our understanding of the functional differentiation and cooccurrence of the genus Ca.Brocadia in wastewater treatment systems.
基金supported by the National Natural Science Foundation of China (No.50921064, 50978249)
文摘Bioaerosol emissions from wastewater and wastewater treatment processes are a significant subgroup of atmospheric aerosols. Most previous work has focused on the evaluation of their biological risks. In this study, however, the adsorption method was applied to reduce airborne microorganisms generated from a pilot scale wastewater treatment facility with oxidation ditch. Results showed adsorption on granule activated carbon （GAC） was an efficient method for the purification of airborne microorganisms. The GAC itself had a maximum adsorption capacity of 2217 CFU/g for airborne bacteria and 225 CFU/g for fungi with a flow rate of 1.50 m^3/hr. Over 85% of airborne bacteria and fungi emitted from the oxidation ditch were adsorbed within 80 hr of continuous operation mode. Most of them had a particle size of 0.65-4.7 μm. Those airborne microorganisms with small particle size were apt to be adsorbed. The SEM/EDAX, BET and Boehm＇s titration methods were applied to analyse the physicochemical characteristics of the GAC. Relationships between GAC surface characteristics and its adsorption performance demonstrated that porous structure, large surface area, and hydrophobicity rendered GAC an effective absorber of airborne microorganisms. Two regenerate methods, ultraviolet irradiation and high pressure vapor, were compared for the regeneration of used activated carbon. High pressure vapor was an effective technique as it totally destroyed the microorganisms adhered to the activated carbon. Microscopic observation was also carried out to investigate original and used adsorbents.
