Objective Despite the adoption of various permeability enhancement technologies,the low permeability of coal reservoir has not been fundamentally improved for the development of coalbed methane(CBM)on the ground or ...Objective Despite the adoption of various permeability enhancement technologies,the low permeability of coal reservoir has not been fundamentally improved for the development of coalbed methane(CBM)on the ground or the control of gas underground.展开更多
Tetrasphaera have been recently identified based on the 16S ribosomal RNA(rRNA)gene as among the most abundant polyphosphate-accumulating organisms(PAOs)in global full-scale wastewater treatment plants(WWTPs)with enha...Tetrasphaera have been recently identified based on the 16S ribosomal RNA(rRNA)gene as among the most abundant polyphosphate-accumulating organisms(PAOs)in global full-scale wastewater treatment plants(WWTPs)with enhanced biological phosphorus removal(EBPR).However,it is unclear how Tetrasphaera PAOs are selectively enriched in the context of the EBPR microbiome.In this study,an EBPR microbiome enriched with Tetrasphaera(accounting for 40%of 16S sequences on day 113)was built using a top-down design approach featuring multicarbon sources and a low dosage of allylthiourea.The microbiome showed enhanced nutrient removal(phosphorus removal~85%and nitrogen removal~80%)and increased phosphorus recovery(up to 23.2 times)compared with the seeding activated sludge from a local full-scale WWTP.The supply of 1 mg·L^(-1)allylthiourea promoted the coselection of Tetrasphaera PAOs and Microlunatus PAOs and sharply reduced the relative abundance of both ammonia oxidizer Nitrosomonas and putative competitors Brevundimonas and Paracoccus,facilitating the establishment of the EBPR microbiome.Based on 16S rRNA gene analysis,a putative novel PAO species,EBPR-ASV0001,was identified with Tetrasphaera japonica as its closest relative.This study provides new knowledge on the establishment of a Tetrasphaera-enriched microbiome facilitated by allylthiourea,which can be further exploited to guide future process upgrading and optimization to achieve and/or enhance simultaneous biological phosphorus and nitrogen removal from high-strength wastewater.展开更多
To elucidate the phosphorus removal and metabolism under various COD / P ratio,a sludge highly enriched in PAOs was used to investigate the impacts of COD / P in batch tests under different carbon supply conditions. A...To elucidate the phosphorus removal and metabolism under various COD / P ratio,a sludge highly enriched in PAOs was used to investigate the impacts of COD / P in batch tests under different carbon supply conditions. Acetate,propionate and a mixture of acetate and propionate at a ratio of 3 ∶ 1( COD basis) was used as carbon sources with the COD / P of 20,15,10 and 5. 0 g COD /gP,respectively. The minimum COD / P ratios for complete P removal were found to be 8. 24 g COD /gP for acetate,11. 40 g COD /gP for propionate and9. 10 g COD /gP for the 3 ∶ 1 mixture of acetate and propionate. Converted to a mass basis,all three cases had a very similar ratio of 7. 7 g VFA /gP,which represented a useful guide for operation of EBPR plants to identify possible shortages in VFAs. The trend in PHV accumulation during the anaerobic period along with the decrease of COD / P ratios suggested that,PAOs may use the TCA pathway for anaerobic VFA uptake to maintain the required NADH production with reduced glycogen degradation. During the aerobic phase,the glycogen pool was reduced but remained enough compared to the requirement for anaerobic VFA uptake,and the synthesis and degradation of glycogen was not the inhibition factor of PAOs.展开更多
According to the plasmon hybridization theory, the plasmon resonance characteristics of the gold nanocrescent/nanoring(NCNR) structure are systematically investigated by the finite element method. It is found that the...According to the plasmon hybridization theory, the plasmon resonance characteristics of the gold nanocrescent/nanoring(NCNR) structure are systematically investigated by the finite element method. It is found that the extinction spectra of NCNR structure exhibit multiple plasmon resonance peaks, which could be attributed to the result of the plasmon couplings between the multipolar plasmon modes of nanocrescent and the dipolar, quadrupolar, hexapolar, octupolar,decapolar plasmon modes of nanoring. By changing the geometric parameters, the intense and separate multiple plasmon resonance peaks are obtained and can be tuned in a wide wavelength range. It is further found that the plasmon coupling induces giant multipole electric field enhancements around the tips of the nanocrescent. The tunable and intense multiple plasmon resonances of NCNR structure may provide effective applications in multiplex biological sensing.展开更多
To achieve stable and efficient nitrogen and phosphorus removal and to investigate the characteristics of the A/A SBR enriched with denitrifying phosphorus removal bacteria(DPB),the whole course of startup was studied...To achieve stable and efficient nitrogen and phosphorus removal and to investigate the characteristics of the A/A SBR enriched with denitrifying phosphorus removal bacteria(DPB),the whole course of startup was studied with two reactors operated in different mode.The reactor I was operated under anaerobic/settling/anoxic/settling mode,and the reactor II was operated under anaerobic/anoxic/settling mode.Differences between the two reactors in removal efficiency of COD,nitrogen and phosphorus were examined.The results indicated that efficient performance could be achieved in both reactors with different startup operation mode,while the phosphorus removal efficiency was improved sooner in reactor I than in reactor II,which suggested that reactor I would supply a more favorable condition for DPB proliferation.Meanwhile,it was observed that the amount of organic substrates consumption had a linear correlation to that of phosphorus release in anaerobic phase when DPB was accumulated in the A/A SBR denitrifying phosphorus removal system.展开更多
The objective of this work is to verify a hypothesis that nitrite accumulation comes from the metabolites of denitrification phosphate accumulating organisms (DPAOs),not denitrifying bacteria.On the precondition of th...The objective of this work is to verify a hypothesis that nitrite accumulation comes from the metabolites of denitrification phosphate accumulating organisms (DPAOs),not denitrifying bacteria.On the precondition of the restriction of denitrifying bacteria in anoxic phase,static experimental test was designed using NO3-as electron acceptor,effluent was removed after sedimentation in anaerobic phase,and the same concentration solution of PO43--P was returned,so that TOC was excluded and denitrification was inhibited in the next phases.A parallel experiment was carried out simultaneously with the normal anaerobic-anoxic progress.The results showed that,in static test,by keeping the normal growth of DPAO and inhibiting denitrification of denitrifying bacteria,P-release in anaerobic and P-uptake in anoxic phase proceeded normally.DPAO had obvious effect on P-removal and the P-removal efficiency was 69%.The effluent concentration of NO3--N and NO2--N was 7.62 mg/L and 6.05 mg/L respectively,compared with parallel experiments,and nitrogen removal rate was lower.No nitrite residue was found in parallel test.Therefore,it can confirm the hypothesis that the metabolites of DPAO are both nitrogen and nitrite when nitrate is taken as electron acceptor,and nitrite is subsequently converted to nitrogen by denitrifying bacteria.展开更多
Nitrous oxide (N2O) emission has been reported to be enhanced during denitrification when internally-stored compounds are used as carbon sources. However, negligible N2O emissions have been detected in the few studi...Nitrous oxide (N2O) emission has been reported to be enhanced during denitrification when internally-stored compounds are used as carbon sources. However, negligible N2O emissions have been detected in the few studies where polyhydroxyalkanoates (PHA) were specifically used. This study investigated and compared the potential enhancement of N2O production, based on utilization of an internally-stored polymer and external carbon (acetate) by a denitrifying phosphorus removal culture. Results indicated that at relatively low chemical oxygen demand-to-nitrogen (COD/N) ratios, more nitrite was reduced to N2O in the presence of an external carbon source as compared to an internal carbon source (PHA). At relatively higher COD/N ratios, similar N2O reduction rates were obtained in all cases regardless of the type of carbon source available. N2O reduction rates were, however, generally higher in the presence of an internal carbon source. Results from the study imply that when the presence of an external carbon source is not sufficient to support denitrification, it is likely competitively utilized by different metabolic pathways of denitrifying polyphosphate accumulating organisms (DPAOs) and other ordinary denitfifiers. This study also reveals that the consumption of PHA is potentially the rate-limiting step for N2O reduction during denitrification.展开更多
Candidatus Accumulibacter has been identified as dominant polyphosphate-accumulating organisms(PAOs) in enhanced biological phosphorus(P) removal(EBPR) from wastewater.This study revealed the relevance of commun...Candidatus Accumulibacter has been identified as dominant polyphosphate-accumulating organisms(PAOs) in enhanced biological phosphorus(P) removal(EBPR) from wastewater.This study revealed the relevance of community structure, abundance and seasonal population dynamics of Candidatus Accumulibacter to process operation of wastewater treatment plants(WWTPs) in China using ppk1 gene as phylogenetic marker. All sludge samples had properties of denitrifying P removal using nitrate as an electron acceptor.Accumulibacter abundance in the anaerobic-anoxic-oxic(A^2O) process was the highest(26%of total bacteria), and higher in winter than in summer with a better EBPR performance.Type-II was the dominant Accumulibacter in all processes, and type-I accounted for a small proportion of total Accumulibacter. The abundance of Clade-IIC as the most dominant clade reached 2.59 × 10~9 cells/g MLSS and accounted for 87.3% of total Accumulibacter. Clade IIC mainly contributed to denitrifying P removal. Clades IIA, IIC and IID were found in all processes, while clade-IIF was only found in oxidation ditch process through phylogenetic analysis. High proportion of clade IID to total Accumulibacter led to poor performance of aerobic P-uptake in inverted A^2O process. Therefore, Accumulibacter clades in WWTPs were diverse, and EBPR performance was closely related to the clade-level community structures and abundances of Accumulibacter.展开更多
Sequencing batch reactor(SBR)for enhanced biological phosphorus removal(EBPR)processes was used to investigate the impact of the temperature shock on the competition between phosphorus-accumulating organisms(PAOs)and ...Sequencing batch reactor(SBR)for enhanced biological phosphorus removal(EBPR)processes was used to investigate the impact of the temperature shock on the competition between phosphorus-accumulating organisms(PAOs)and glycogen accumulating organisms(GAOs)in start-up stage.During the 34 days operation,SBR was set with temperature variation(0-5 d,22±1℃;6-13 d,29±1℃;14-34 d,14±1℃).PAOs and GAOs were analyzed by fluorescent in situ hybridization(FISH),and intracellular polyphosphate granules were stained by Neisser-stain.The results showed that the influence of temperature shock on PAOs’abundance was more serious than that on GAOs in the enriching process.Under sudden and substantially temperature variation,from 22±1℃ to 29±1℃ and then to 14±1℃,the domination of PAOs was deteriorated.After temperature shock,PAOs’competitive advantages at low temperature that concluded in other study did not appear in our study.As mesophilic,GAOs(indicated by Alphaproteobacteria and Gammaproteobacteria)were more temperature adaptive and better grew and took the domination at 14±1℃ in the end.In the competition process,organisms of tetrad forming organisms(TFOs)-like shape which were considered as typical GAOs,were observed.With the evidence of poly-P granules containing by Neisser-straining and result of FISH,these organisms of TFOs-like shape were better to be assumed as adaption state or a special self-protecting shape of PAOs.展开更多
In order to achieve simultaneous nitrogen and phosphorus removal in the biological treatment process,denitrifying phosphorus accumulation(DNPA)and its affecting factors were studied in a sequencing batch reactor(SBR)w...In order to achieve simultaneous nitrogen and phosphorus removal in the biological treatment process,denitrifying phosphorus accumulation(DNPA)and its affecting factors were studied in a sequencing batch reactor(SBR)with synthetic wastewater.The results showed that when acetate was used as the sole carbon resource in the influent,the sludge acclimatized under anaerobic/aerobic operation had good phos-phorus removal ability.Denitrifying phosphorus accumulation was observed soon when fed with nitrate instead of aeration following the anaerobic stage,which is a vital premise to DNPA.If DNPA sludge is fed with nitrate prior to the anaerobic stage,the DNPA would weaken or even disappear.At the high concen-tration of nitrate fed in the anoxic stage,the longer anoxic time needed,the better the DNPA was.Induced DNPA did not disap-pear even though an aerobic stage followed the anoxic stage,but the shorter the aerobic stage lasted,the higher the proportions of phosphorus removal via DNPA to total removal.展开更多
基金financially supported by the National Natural Sciences Foundation of China(grant No.NSFC 41472127)
文摘Objective Despite the adoption of various permeability enhancement technologies,the low permeability of coal reservoir has not been fundamentally improved for the development of coalbed methane(CBM)on the ground or the control of gas underground.
基金supported by the Key Research and Development Program of Zhejiang(2022C03075)National Natural Science Foundation of China(22241603)Zhejiang Provincial Natural Science Foundation of China(LR22D010001)。
文摘Tetrasphaera have been recently identified based on the 16S ribosomal RNA(rRNA)gene as among the most abundant polyphosphate-accumulating organisms(PAOs)in global full-scale wastewater treatment plants(WWTPs)with enhanced biological phosphorus removal(EBPR).However,it is unclear how Tetrasphaera PAOs are selectively enriched in the context of the EBPR microbiome.In this study,an EBPR microbiome enriched with Tetrasphaera(accounting for 40%of 16S sequences on day 113)was built using a top-down design approach featuring multicarbon sources and a low dosage of allylthiourea.The microbiome showed enhanced nutrient removal(phosphorus removal~85%and nitrogen removal~80%)and increased phosphorus recovery(up to 23.2 times)compared with the seeding activated sludge from a local full-scale WWTP.The supply of 1 mg·L^(-1)allylthiourea promoted the coselection of Tetrasphaera PAOs and Microlunatus PAOs and sharply reduced the relative abundance of both ammonia oxidizer Nitrosomonas and putative competitors Brevundimonas and Paracoccus,facilitating the establishment of the EBPR microbiome.Based on 16S rRNA gene analysis,a putative novel PAO species,EBPR-ASV0001,was identified with Tetrasphaera japonica as its closest relative.This study provides new knowledge on the establishment of a Tetrasphaera-enriched microbiome facilitated by allylthiourea,which can be further exploited to guide future process upgrading and optimization to achieve and/or enhance simultaneous biological phosphorus and nitrogen removal from high-strength wastewater.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51278143,51408162)the Postdoctoral Foundation of China(Grant No.2013M530161)
文摘To elucidate the phosphorus removal and metabolism under various COD / P ratio,a sludge highly enriched in PAOs was used to investigate the impacts of COD / P in batch tests under different carbon supply conditions. Acetate,propionate and a mixture of acetate and propionate at a ratio of 3 ∶ 1( COD basis) was used as carbon sources with the COD / P of 20,15,10 and 5. 0 g COD /gP,respectively. The minimum COD / P ratios for complete P removal were found to be 8. 24 g COD /gP for acetate,11. 40 g COD /gP for propionate and9. 10 g COD /gP for the 3 ∶ 1 mixture of acetate and propionate. Converted to a mass basis,all three cases had a very similar ratio of 7. 7 g VFA /gP,which represented a useful guide for operation of EBPR plants to identify possible shortages in VFAs. The trend in PHV accumulation during the anaerobic period along with the decrease of COD / P ratios suggested that,PAOs may use the TCA pathway for anaerobic VFA uptake to maintain the required NADH production with reduced glycogen degradation. During the aerobic phase,the glycogen pool was reduced but remained enough compared to the requirement for anaerobic VFA uptake,and the synthesis and degradation of glycogen was not the inhibition factor of PAOs.
基金supported by the National Natural Science Foundation of China(Grant Nos.61275153 and 61320106014)the Natural Science Foundation of Zhejiang Province,China(Grant No.LY12A04002)+1 种基金the Natural Science Foundation of Ningbo City,China(Grant Nos.2010D10018 and 2012A610107)the K.C.Wong Magna Foundation of Ningbo University,China
文摘According to the plasmon hybridization theory, the plasmon resonance characteristics of the gold nanocrescent/nanoring(NCNR) structure are systematically investigated by the finite element method. It is found that the extinction spectra of NCNR structure exhibit multiple plasmon resonance peaks, which could be attributed to the result of the plasmon couplings between the multipolar plasmon modes of nanocrescent and the dipolar, quadrupolar, hexapolar, octupolar,decapolar plasmon modes of nanoring. By changing the geometric parameters, the intense and separate multiple plasmon resonance peaks are obtained and can be tuned in a wide wavelength range. It is further found that the plasmon coupling induces giant multipole electric field enhancements around the tips of the nanocrescent. The tunable and intense multiple plasmon resonances of NCNR structure may provide effective applications in multiplex biological sensing.
基金Sponsored by the National Natural Science Foundation of China(Grant No.50778052)Development Program for Outstanding Young Teachers in Harbin Institute of Technology(Grant No.NQQQ92324547)
文摘To achieve stable and efficient nitrogen and phosphorus removal and to investigate the characteristics of the A/A SBR enriched with denitrifying phosphorus removal bacteria(DPB),the whole course of startup was studied with two reactors operated in different mode.The reactor I was operated under anaerobic/settling/anoxic/settling mode,and the reactor II was operated under anaerobic/anoxic/settling mode.Differences between the two reactors in removal efficiency of COD,nitrogen and phosphorus were examined.The results indicated that efficient performance could be achieved in both reactors with different startup operation mode,while the phosphorus removal efficiency was improved sooner in reactor I than in reactor II,which suggested that reactor I would supply a more favorable condition for DPB proliferation.Meanwhile,it was observed that the amount of organic substrates consumption had a linear correlation to that of phosphorus release in anaerobic phase when DPB was accumulated in the A/A SBR denitrifying phosphorus removal system.
基金Sponsored by the Key Project of the National Natural Science Foundation of China (Grant No. 50638020)
文摘The objective of this work is to verify a hypothesis that nitrite accumulation comes from the metabolites of denitrification phosphate accumulating organisms (DPAOs),not denitrifying bacteria.On the precondition of the restriction of denitrifying bacteria in anoxic phase,static experimental test was designed using NO3-as electron acceptor,effluent was removed after sedimentation in anaerobic phase,and the same concentration solution of PO43--P was returned,so that TOC was excluded and denitrification was inhibited in the next phases.A parallel experiment was carried out simultaneously with the normal anaerobic-anoxic progress.The results showed that,in static test,by keeping the normal growth of DPAO and inhibiting denitrification of denitrifying bacteria,P-release in anaerobic and P-uptake in anoxic phase proceeded normally.DPAO had obvious effect on P-removal and the P-removal efficiency was 69%.The effluent concentration of NO3--N and NO2--N was 7.62 mg/L and 6.05 mg/L respectively,compared with parallel experiments,and nitrogen removal rate was lower.No nitrite residue was found in parallel test.Therefore,it can confirm the hypothesis that the metabolites of DPAO are both nitrogen and nitrite when nitrate is taken as electron acceptor,and nitrite is subsequently converted to nitrogen by denitrifying bacteria.
文摘Nitrous oxide (N2O) emission has been reported to be enhanced during denitrification when internally-stored compounds are used as carbon sources. However, negligible N2O emissions have been detected in the few studies where polyhydroxyalkanoates (PHA) were specifically used. This study investigated and compared the potential enhancement of N2O production, based on utilization of an internally-stored polymer and external carbon (acetate) by a denitrifying phosphorus removal culture. Results indicated that at relatively low chemical oxygen demand-to-nitrogen (COD/N) ratios, more nitrite was reduced to N2O in the presence of an external carbon source as compared to an internal carbon source (PHA). At relatively higher COD/N ratios, similar N2O reduction rates were obtained in all cases regardless of the type of carbon source available. N2O reduction rates were, however, generally higher in the presence of an internal carbon source. Results from the study imply that when the presence of an external carbon source is not sufficient to support denitrification, it is likely competitively utilized by different metabolic pathways of denitrifying polyphosphate accumulating organisms (DPAOs) and other ordinary denitfifiers. This study also reveals that the consumption of PHA is potentially the rate-limiting step for N2O reduction during denitrification.
基金supported by the National Key Research and Development Programme of China (No. 2016YFC0401103)the Natural Science Foundation of China (No. 51578016)the Natural Science Foundation of Beijing (No. 8172014)
文摘Candidatus Accumulibacter has been identified as dominant polyphosphate-accumulating organisms(PAOs) in enhanced biological phosphorus(P) removal(EBPR) from wastewater.This study revealed the relevance of community structure, abundance and seasonal population dynamics of Candidatus Accumulibacter to process operation of wastewater treatment plants(WWTPs) in China using ppk1 gene as phylogenetic marker. All sludge samples had properties of denitrifying P removal using nitrate as an electron acceptor.Accumulibacter abundance in the anaerobic-anoxic-oxic(A^2O) process was the highest(26%of total bacteria), and higher in winter than in summer with a better EBPR performance.Type-II was the dominant Accumulibacter in all processes, and type-I accounted for a small proportion of total Accumulibacter. The abundance of Clade-IIC as the most dominant clade reached 2.59 × 10~9 cells/g MLSS and accounted for 87.3% of total Accumulibacter. Clade IIC mainly contributed to denitrifying P removal. Clades IIA, IIC and IID were found in all processes, while clade-IIF was only found in oxidation ditch process through phylogenetic analysis. High proportion of clade IID to total Accumulibacter led to poor performance of aerobic P-uptake in inverted A^2O process. Therefore, Accumulibacter clades in WWTPs were diverse, and EBPR performance was closely related to the clade-level community structures and abundances of Accumulibacter.
基金This research was supported by the National Nature Science Foundation of China(Grant No.50821002,National Creative Research Groups)Mega-Projects of Science Research for Water(No.2008ZX07207-005-003)the National Natural Science Foundation of China(Grant No.50638020).
文摘Sequencing batch reactor(SBR)for enhanced biological phosphorus removal(EBPR)processes was used to investigate the impact of the temperature shock on the competition between phosphorus-accumulating organisms(PAOs)and glycogen accumulating organisms(GAOs)in start-up stage.During the 34 days operation,SBR was set with temperature variation(0-5 d,22±1℃;6-13 d,29±1℃;14-34 d,14±1℃).PAOs and GAOs were analyzed by fluorescent in situ hybridization(FISH),and intracellular polyphosphate granules were stained by Neisser-stain.The results showed that the influence of temperature shock on PAOs’abundance was more serious than that on GAOs in the enriching process.Under sudden and substantially temperature variation,from 22±1℃ to 29±1℃ and then to 14±1℃,the domination of PAOs was deteriorated.After temperature shock,PAOs’competitive advantages at low temperature that concluded in other study did not appear in our study.As mesophilic,GAOs(indicated by Alphaproteobacteria and Gammaproteobacteria)were more temperature adaptive and better grew and took the domination at 14±1℃ in the end.In the competition process,organisms of tetrad forming organisms(TFOs)-like shape which were considered as typical GAOs,were observed.With the evidence of poly-P granules containing by Neisser-straining and result of FISH,these organisms of TFOs-like shape were better to be assumed as adaption state or a special self-protecting shape of PAOs.
基金This study was supported by the National Natural Science Foundation of China(Grant No.5008014).
文摘In order to achieve simultaneous nitrogen and phosphorus removal in the biological treatment process,denitrifying phosphorus accumulation(DNPA)and its affecting factors were studied in a sequencing batch reactor(SBR)with synthetic wastewater.The results showed that when acetate was used as the sole carbon resource in the influent,the sludge acclimatized under anaerobic/aerobic operation had good phos-phorus removal ability.Denitrifying phosphorus accumulation was observed soon when fed with nitrate instead of aeration following the anaerobic stage,which is a vital premise to DNPA.If DNPA sludge is fed with nitrate prior to the anaerobic stage,the DNPA would weaken or even disappear.At the high concen-tration of nitrate fed in the anoxic stage,the longer anoxic time needed,the better the DNPA was.Induced DNPA did not disap-pear even though an aerobic stage followed the anoxic stage,but the shorter the aerobic stage lasted,the higher the proportions of phosphorus removal via DNPA to total removal.