The present lab-scale research reveals the enrichment of anaerobic ammonium oxidation microorganism from methanogenic anaerobic granular sludge and the effect of inorganic carbon(sodium bicarbonate)on anaerobic ammoni...The present lab-scale research reveals the enrichment of anaerobic ammonium oxidation microorganism from methanogenic anaerobic granular sludge and the effect of inorganic carbon(sodium bicarbonate)on anaerobic ammonium oxidation.The enrichment of anammox bacteria was carried out in a 7.0-L sequencing batch reactor(SBR)and the effect of bicarbonate on anammox was conducted in a 3.0-L SBR.Research results,especially the biomass,showed first signs of anammox activity after 54 d cultivation with synthetic wastewater,when the pH was controlled between 7.5 and 8.3,the temperature was 35°C.The anammox activity increased as the influent bicarbonate concentration increased from 1.0to 1.5 g/L,and then,was inhibited as the bicarbonate concentration approached 2.0 g/L.However,the activity could be restored by the reduction of bicarbonate concentration to 1.0 g/L,as shown by rapid conversion of ammonium,and nitrite and nitrate production with normal stoichiometry.The optimization of the bicarbonate concentration in the reactor could increase the anammox rate up to 66.4 mgN/(L-d).展开更多
Soil degradation,characterized by declines in nutrient status and simultaneous accumulation of pesticide residues,is a major problem affecting agricultural ecosystems.Previous studies indicate that biochar application...Soil degradation,characterized by declines in nutrient status and simultaneous accumulation of pesticide residues,is a major problem affecting agricultural ecosystems.Previous studies indicate that biochar application to soil has promise as a practical method to alleviate these pressures:increasing crop yield and enhancing pesticide degradation.Here,we review the roles of biochar in both chemical and biological promotion of pesticide degradation and the potential benefits of biochar relating to the efficiency of fertilizer use,availability of nutrients,and nutrient exchange.Biochar typically has a high surface area featuring many functional groups,a high cation exchange capacity,and high stability.Major factors that impact on the nutrient retention characteristics of biochar(e.g.,feedstock,pyrolysis temperature,and application rate) are also discussed herein.Nonetheless,more studies of the long-term impacts on soil properties from biochar addition are still required before it can be possible to accurately quantify the sustainability of this approach to sequester carbon and restore soil function.展开更多
Uneven distribution of volatile organic compounds （VOCs） and biomass, and excess biomass accumulation in some biofilters hinder the application of biofiltration technology. An innovative multilayer rotating drum bio...Uneven distribution of volatile organic compounds （VOCs） and biomass, and excess biomass accumulation in some biofilters hinder the application of biofiltration technology. An innovative multilayer rotating drum biofilter （RDB） was developed to correct these problems. The RDB was operated at an empty bed contact time （EBCT） of 30 s and a rotational rate of 1.0 r/min. Diethyl ether was chosen as the model VOC. Performance of the RDB was evaluated at organic loading rates of 32,1, 64.2, 128, and 256 g ether/（m^3·h） （16.06 g ether/（m^3·h） ≈ 1.0 kg chemical oxygen demand （COD）/（m^3·d））. The EBCT and organic loading rates were recorded on the basis of the medium volume. Results show that the ether removal efficiency decreased with an increased VOC loading rate. Ether removal efficiencies exceeding 99% were achieved without biomass control even at a high VOC loading rate of 128 g ether/（m^3·h）. However, when the VOC loading rate was increased to 256 g ether/（m^3·h）, the average removal efficiency dropped to 43%. Nutrient limitation possibly contributed to the drop in ether removal efficiency. High biomass accumulation rate was also observed in the medium at the two higher ether loading rates, and removal of the excess biomass in the media was necessary to maintain stable performance. This work showed that the RDB is effective in the removal of diethyl ether from waste gas streams even at high organic loading rates. The results might help establish criteria for designing and operating RDBs.展开更多
目的探讨神经内镜锁孔开颅治疗急性外伤性硬膜下血肿的有效性和安全性。方法回顾性分析2016年1月至2022年1月福建省立医院南院神经外科手术治疗的40例急性外伤性硬膜下血肿患者的临床资料。其中20例采用神经内镜锁孔开颅血肿清除术(微创...目的探讨神经内镜锁孔开颅治疗急性外伤性硬膜下血肿的有效性和安全性。方法回顾性分析2016年1月至2022年1月福建省立医院南院神经外科手术治疗的40例急性外伤性硬膜下血肿患者的临床资料。其中20例采用神经内镜锁孔开颅血肿清除术(微创组),20例采用传统大骨瓣开颅手术治疗(传统组)。两组患者性别、年龄、术前硬膜下血肿量等基线资料的差异均无统计学意义(均P>0.05),具有可比性。分析比较两组患者的手术情况(包括手术时长及术中出血量等)、术后1 d格拉斯哥昏迷评分(GCS)、术后并发症及术后6个月格拉斯哥预后分级(GOS)。结果两组患者均顺利完成手术,微创组术中无一例扩大手术。与传统组比较,微创组的手术时长较短[分别为(73.8±6.7)min、(138.3±16.8)min,t=15.92]、术中出血量较少[分别为(26.7±4.7)ml、(96.5±13.1)ml,t=22.46]、术后血肿残余量较少[分别为(3.5±1.3)ml、(7.6±2.6)ml,t=6.24]、住院时长较短[分别为(10.3±2.9)d、(13.8±3.2)d,t=3.71],差异均具有统计学意义(均P<0.05)。与术前比较,微创组和传统组的术后1 d GCS均升高,差异均具有统计学意义(配对t值分别为15.70、13.65,均P<0.001)。两组比较,术后1 d GCS以及术后发生癫痫、肺部感染及颅内感染者占比的差异均无统计学意义(均P>0.05)。术后6个月,所有患者的GOS均为Ⅴ级,两组比较差异无统计学意义(P=1.000)。结论与传统大骨瓣开颅手术比较,采用神经内镜锁孔开颅手术治疗急性外伤性硬膜下血肿可缩短手术和住院时长,减少术中出血和血肿残留,而并发症发生比例和预后情况相近,是一种安全、有效、微创的方法。展开更多
The nitrogen removal mechanism was studied and analyzed when treating the ammonium-rich landfill leachate by a set of sequencing batch biofilm reactors(SBBRs),which was designed independently.At the liquid temperature...The nitrogen removal mechanism was studied and analyzed when treating the ammonium-rich landfill leachate by a set of sequencing batch biofilm reactors(SBBRs),which was designed independently.At the liquid temperature of(32P0.4)°C,and after a 58-days domestica-tion period and a 33-days stabilization period,the efficiency of ammonium removal in the SBBR went up to 95%.Highly frequent intermittent aeration suppressed the activity of nitratebacteria,and also eliminated the influence on the activity of anaerobic ammonium oxidation(ANAMMOX)bacteria and nitritebacteria.This influence was caused by the accumulation of nitrous acid and the undulation of pH.During the aeration stage,the concentration of dissolved oxygen was controlled at 1.2-1.4 mg/L.The nitritebacteria became dominant and nitrite accumulated gradually.During the anoxic stage,along with the concentration debasement of the dissolved oxygen,ANAMMOX bacteria became domi-nant;then,the nitrite that was accumulated in the aeration stage was wiped off with ammonium simultaneously.展开更多
The method of determining grid sizes of finite element method of water quality models is presented on the basis of characteristics of pollutant distributed in the just downstream grid of discharge. A given length of t...The method of determining grid sizes of finite element method of water quality models is presented on the basis of characteristics of pollutant distributed in the just downstream grid of discharge. A given length of the grid is applied to calculate the minimum distance for the pollutant to complete mixing in the lateral direction in the just downstream grid of the discharge, and the minimum distance is regarded as the maximum width of the grid. Application of the maximum width of the grid and flow rate per unit width of the river results in the number of flow zones in the lateral direction of the river. Consequently division of grids and numerical calculation of water quality with finite element method can be carried out on the basis of available method and topographic map of the river course. Analysis of sensitivity shows that the effect of the width of the river and the effect of the length of the grids on the minimum number of flow zones in the lateral direction is relatively small, and that the effect of the given lateral mixing degree of the pollutants on the minimum number of flow zones is acceptable, which indicates that the method presented is relatively stable. The method can avoid the blindness and randomness in determining the number of flow zones, and can decrease the amount of computation under the condition that the accuracy requirement is met. The problem that determining the sizes of the grids must rely on empirical knowledge has been solved.展开更多
To investigate the chief reason for phosphorus uptake by microorganisms affected by substrates in sequencing batch reactors with the single-stage oxic process,two typical substrates,glucose (R1) and acetate (R2) were ...To investigate the chief reason for phosphorus uptake by microorganisms affected by substrates in sequencing batch reactors with the single-stage oxic process,two typical substrates,glucose (R1) and acetate (R2) were used as the sole carbon source,and the performances of phosphorus removal and the changes of intracellular storage were compared. The experimental results showed that the phenomenon of excess phosphorus uptake was observed in two reactors,but bacteria's capability to take in phosphorus and its intracellular storage were obviously different under the same operational condition. After steady-state operation,total phosphorus (TP) removed per MLVSS in R1 and R2 was 6.7―7.4 and 2.7―3.2 mg/g,respectively. The energy storage of poly-β-hydroxyalkanoates (PHA) was nearly constant in R1 during the whole period,and another aerobic storage of glycogen was accumulated (the max accumulation of glycogen was 3.21 mmol-C/g) when external substrate was consumed,and then was decreased to the initial level. However in R2,PHA and glycogen were both accumulated (2.1 and 0.55 mmol-C/g,respectively) when external substrate was consumed,but they showed different changes after the period of external consumption. Compared to rapid decrease of PHA to the initial level,glycogen continued accumulating to the peak (0.88 mmol-C/g) in 2 h of aeration before decreasing. During the aeration,the accumulations/transformations of internal carbon sources in R1 were higher than those in R2. In addition,obvious TP releases were both observed in R1 and R2 other than PHA and glycogen during the long-term idle period; moreover,the release content of phosphorus in R1 was also higher than that in R2. The researches indicated that different aerobic metabolism of substrate occurred in R1 and R2 due to the different carbon sources in influent,resulting in different types and contents of aerobic storage accumulated/translated in bacteria of R1 and R2. As a result,ATP content provided for phosphorus uptake was different in R1 and R2,and the capability to take up phosphorus was also different from each other.展开更多
文摘The present lab-scale research reveals the enrichment of anaerobic ammonium oxidation microorganism from methanogenic anaerobic granular sludge and the effect of inorganic carbon(sodium bicarbonate)on anaerobic ammonium oxidation.The enrichment of anammox bacteria was carried out in a 7.0-L sequencing batch reactor(SBR)and the effect of bicarbonate on anammox was conducted in a 3.0-L SBR.Research results,especially the biomass,showed first signs of anammox activity after 54 d cultivation with synthetic wastewater,when the pH was controlled between 7.5 and 8.3,the temperature was 35°C.The anammox activity increased as the influent bicarbonate concentration increased from 1.0to 1.5 g/L,and then,was inhibited as the bicarbonate concentration approached 2.0 g/L.However,the activity could be restored by the reduction of bicarbonate concentration to 1.0 g/L,as shown by rapid conversion of ammonium,and nitrite and nitrate production with normal stoichiometry.The optimization of the bicarbonate concentration in the reactor could increase the anammox rate up to 66.4 mgN/(L-d).
基金financially supported by the National Natural Science Foundation and Innovation Group of China(Nos.41271332 and 51521006)
文摘Soil degradation,characterized by declines in nutrient status and simultaneous accumulation of pesticide residues,is a major problem affecting agricultural ecosystems.Previous studies indicate that biochar application to soil has promise as a practical method to alleviate these pressures:increasing crop yield and enhancing pesticide degradation.Here,we review the roles of biochar in both chemical and biological promotion of pesticide degradation and the potential benefits of biochar relating to the efficiency of fertilizer use,availability of nutrients,and nutrient exchange.Biochar typically has a high surface area featuring many functional groups,a high cation exchange capacity,and high stability.Major factors that impact on the nutrient retention characteristics of biochar(e.g.,feedstock,pyrolysis temperature,and application rate) are also discussed herein.Nonetheless,more studies of the long-term impacts on soil properties from biochar addition are still required before it can be possible to accurately quantify the sustainability of this approach to sequester carbon and restore soil function.
基金partially supported by the National Natural Science Foundation of China(No.50778066)the Program for New Century Excellent Talents in University from the Ministry of Education of China(No.NCET-05-0701)the University of Cincinnati.
文摘Uneven distribution of volatile organic compounds （VOCs） and biomass, and excess biomass accumulation in some biofilters hinder the application of biofiltration technology. An innovative multilayer rotating drum biofilter （RDB） was developed to correct these problems. The RDB was operated at an empty bed contact time （EBCT） of 30 s and a rotational rate of 1.0 r/min. Diethyl ether was chosen as the model VOC. Performance of the RDB was evaluated at organic loading rates of 32,1, 64.2, 128, and 256 g ether/（m^3·h） （16.06 g ether/（m^3·h） ≈ 1.0 kg chemical oxygen demand （COD）/（m^3·d））. The EBCT and organic loading rates were recorded on the basis of the medium volume. Results show that the ether removal efficiency decreased with an increased VOC loading rate. Ether removal efficiencies exceeding 99% were achieved without biomass control even at a high VOC loading rate of 128 g ether/（m^3·h）. However, when the VOC loading rate was increased to 256 g ether/（m^3·h）, the average removal efficiency dropped to 43%. Nutrient limitation possibly contributed to the drop in ether removal efficiency. High biomass accumulation rate was also observed in the medium at the two higher ether loading rates, and removal of the excess biomass in the media was necessary to maintain stable performance. This work showed that the RDB is effective in the removal of diethyl ether from waste gas streams even at high organic loading rates. The results might help establish criteria for designing and operating RDBs.
文摘目的探讨神经内镜锁孔开颅治疗急性外伤性硬膜下血肿的有效性和安全性。方法回顾性分析2016年1月至2022年1月福建省立医院南院神经外科手术治疗的40例急性外伤性硬膜下血肿患者的临床资料。其中20例采用神经内镜锁孔开颅血肿清除术(微创组),20例采用传统大骨瓣开颅手术治疗(传统组)。两组患者性别、年龄、术前硬膜下血肿量等基线资料的差异均无统计学意义(均P>0.05),具有可比性。分析比较两组患者的手术情况(包括手术时长及术中出血量等)、术后1 d格拉斯哥昏迷评分(GCS)、术后并发症及术后6个月格拉斯哥预后分级(GOS)。结果两组患者均顺利完成手术,微创组术中无一例扩大手术。与传统组比较,微创组的手术时长较短[分别为(73.8±6.7)min、(138.3±16.8)min,t=15.92]、术中出血量较少[分别为(26.7±4.7)ml、(96.5±13.1)ml,t=22.46]、术后血肿残余量较少[分别为(3.5±1.3)ml、(7.6±2.6)ml,t=6.24]、住院时长较短[分别为(10.3±2.9)d、(13.8±3.2)d,t=3.71],差异均具有统计学意义(均P<0.05)。与术前比较,微创组和传统组的术后1 d GCS均升高,差异均具有统计学意义(配对t值分别为15.70、13.65,均P<0.001)。两组比较,术后1 d GCS以及术后发生癫痫、肺部感染及颅内感染者占比的差异均无统计学意义(均P>0.05)。术后6个月,所有患者的GOS均为Ⅴ级,两组比较差异无统计学意义(P=1.000)。结论与传统大骨瓣开颅手术比较,采用神经内镜锁孔开颅手术治疗急性外伤性硬膜下血肿可缩短手术和住院时长,减少术中出血和血肿残留,而并发症发生比例和预后情况相近,是一种安全、有效、微创的方法。
基金This work was supported by the National Natural Science Foundation of China(Grant No.50478053)the National High-Tech Research and Development(863)Program(Grant No.2003AA644010)the National Natural Science Foundation of Hunan Province(Grant No.04JJ3004,Grant No.05JJ2004).
文摘The nitrogen removal mechanism was studied and analyzed when treating the ammonium-rich landfill leachate by a set of sequencing batch biofilm reactors(SBBRs),which was designed independently.At the liquid temperature of(32P0.4)°C,and after a 58-days domestica-tion period and a 33-days stabilization period,the efficiency of ammonium removal in the SBBR went up to 95%.Highly frequent intermittent aeration suppressed the activity of nitratebacteria,and also eliminated the influence on the activity of anaerobic ammonium oxidation(ANAMMOX)bacteria and nitritebacteria.This influence was caused by the accumulation of nitrous acid and the undulation of pH.During the aeration stage,the concentration of dissolved oxygen was controlled at 1.2-1.4 mg/L.The nitritebacteria became dominant and nitrite accumulated gradually.During the anoxic stage,along with the concentration debasement of the dissolved oxygen,ANAMMOX bacteria became domi-nant;then,the nitrite that was accumulated in the aeration stage was wiped off with ammonium simultaneously.
文摘The method of determining grid sizes of finite element method of water quality models is presented on the basis of characteristics of pollutant distributed in the just downstream grid of discharge. A given length of the grid is applied to calculate the minimum distance for the pollutant to complete mixing in the lateral direction in the just downstream grid of the discharge, and the minimum distance is regarded as the maximum width of the grid. Application of the maximum width of the grid and flow rate per unit width of the river results in the number of flow zones in the lateral direction of the river. Consequently division of grids and numerical calculation of water quality with finite element method can be carried out on the basis of available method and topographic map of the river course. Analysis of sensitivity shows that the effect of the width of the river and the effect of the length of the grids on the minimum number of flow zones in the lateral direction is relatively small, and that the effect of the given lateral mixing degree of the pollutants on the minimum number of flow zones is acceptable, which indicates that the method presented is relatively stable. The method can avoid the blindness and randomness in determining the number of flow zones, and can decrease the amount of computation under the condition that the accuracy requirement is met. The problem that determining the sizes of the grids must rely on empirical knowledge has been solved.
基金Supported by the National Natural Science Foundation of China (Grant No. 50478054)the Program for NCET in University (Grant No. 0770)
文摘To investigate the chief reason for phosphorus uptake by microorganisms affected by substrates in sequencing batch reactors with the single-stage oxic process,two typical substrates,glucose (R1) and acetate (R2) were used as the sole carbon source,and the performances of phosphorus removal and the changes of intracellular storage were compared. The experimental results showed that the phenomenon of excess phosphorus uptake was observed in two reactors,but bacteria's capability to take in phosphorus and its intracellular storage were obviously different under the same operational condition. After steady-state operation,total phosphorus (TP) removed per MLVSS in R1 and R2 was 6.7―7.4 and 2.7―3.2 mg/g,respectively. The energy storage of poly-β-hydroxyalkanoates (PHA) was nearly constant in R1 during the whole period,and another aerobic storage of glycogen was accumulated (the max accumulation of glycogen was 3.21 mmol-C/g) when external substrate was consumed,and then was decreased to the initial level. However in R2,PHA and glycogen were both accumulated (2.1 and 0.55 mmol-C/g,respectively) when external substrate was consumed,but they showed different changes after the period of external consumption. Compared to rapid decrease of PHA to the initial level,glycogen continued accumulating to the peak (0.88 mmol-C/g) in 2 h of aeration before decreasing. During the aeration,the accumulations/transformations of internal carbon sources in R1 were higher than those in R2. In addition,obvious TP releases were both observed in R1 and R2 other than PHA and glycogen during the long-term idle period; moreover,the release content of phosphorus in R1 was also higher than that in R2. The researches indicated that different aerobic metabolism of substrate occurred in R1 and R2 due to the different carbon sources in influent,resulting in different types and contents of aerobic storage accumulated/translated in bacteria of R1 and R2. As a result,ATP content provided for phosphorus uptake was different in R1 and R2,and the capability to take up phosphorus was also different from each other.
