Seashore landfill aquifers are environments of special physicochemical conditions (high organic load and high sa- linity), and microbes in leachate-polluted aquifers play a significant role for intrinsic bioremediatio...Seashore landfill aquifers are environments of special physicochemical conditions (high organic load and high sa- linity), and microbes in leachate-polluted aquifers play a significant role for intrinsic bioremediation. In order to characterize microbial diversity and look for clues on the relationship between microbial community structure and hydrochemistry, a cul- ture-independent examination of a typical groundwater sample obtained from a seashore landfill was conducted by sequence analysis of 16S rDNA clone library. Two sets of universal 16S rDNA primers were used to amplify DNA extracted from the groundwater so that problems arising from primer efficiency and specificity could be reduced. Of 74 clones randomly selected from the libraries, 30 contained unique sequences whose analysis showed that the majority of them belonged to bacteria (95.9%), with Proteobacteria (63.5%) being the dominant division. One archaeal sequence and one eukaryotic sequence were found as well. Bacterial sequences belonging to the following phylogenic groups were identified: Bacteroidetes (20.3%), β, γ, δ and ε-subdivisions of Proteobacteria (47.3%, 9.5%, 5.4% and 1.3%, respectively), Firmicutes (1.4%), Actinobacteria (2.7%), Cyanobacteria (2.7%). The percentages of Proteobacteria and Bacteroides in seawater were greater than those in the groundwater from a non-seashore landfill, indicating a possible influence of seawater. Quite a few sequences had close relatives in marine or hypersaline environments. Many sequences showed affiliations with microbes involved in anaerobic fermentation. The remarkable abundance of sequences related to (per)chlorate-reducing bacteria (ClRB) in the groundwater was significant and worthy of further study.展开更多
The mechanical dewatering of activated sludge is troublesome due to its high compressibility of solids. The dewatering can be enhanced dramatically by the use of electroosmosis,in which an electric field is applied to...The mechanical dewatering of activated sludge is troublesome due to its high compressibility of solids. The dewatering can be enhanced dramatically by the use of electroosmosis,in which an electric field is applied to the sludge cake.In this study,the influence of filter cloth on the cathode on the dewatering of activated sludge was investigated.It was found that thicker filter cloth led to lower water removal from the sludge cake,so a stainless steel cathode net with small pore size instead of filter cloth was applied,which improves the dewatering efficiency and reduces the electric power consumption.Moreover,water absorbent materials were helpful to remove the water from the sludge cake.For the electroosmotic dewatering at 7 kPa and 24 V·cm-1,the water content in the sludge cake decreased to 60%(by mass) with the average 0.075 kW·h·kg-1of water removed by using the cathode net.展开更多
Agro-chemical transport processes at different scales are discussed and relevant opening questions areidentified by literature review to make some suggestions concerning the improvement of research methods forfield sc...Agro-chemical transport processes at different scales are discussed and relevant opening questions areidentified by literature review to make some suggestions concerning the improvement of research methods forfield scale solute transport by aid of evaluation of existing models, and examining transport behaviors of solutein vadose zones on different scales. The results indicate that present research progress and understanding onfield scale solute transport have not yet been enough to guarantee the use of our models for the management offield solute movement. Much more research work needs to be done, particularly, in aspects of high resolutionof spatial structures relevant to the hydraulic and transport properties, explicit numerical simulation of actualstructure on field scale and field measurement corroborated with model development.展开更多
基金Project (No. 20377030) supported by the National Natural ScienceFoundation of China
文摘Seashore landfill aquifers are environments of special physicochemical conditions (high organic load and high sa- linity), and microbes in leachate-polluted aquifers play a significant role for intrinsic bioremediation. In order to characterize microbial diversity and look for clues on the relationship between microbial community structure and hydrochemistry, a cul- ture-independent examination of a typical groundwater sample obtained from a seashore landfill was conducted by sequence analysis of 16S rDNA clone library. Two sets of universal 16S rDNA primers were used to amplify DNA extracted from the groundwater so that problems arising from primer efficiency and specificity could be reduced. Of 74 clones randomly selected from the libraries, 30 contained unique sequences whose analysis showed that the majority of them belonged to bacteria (95.9%), with Proteobacteria (63.5%) being the dominant division. One archaeal sequence and one eukaryotic sequence were found as well. Bacterial sequences belonging to the following phylogenic groups were identified: Bacteroidetes (20.3%), β, γ, δ and ε-subdivisions of Proteobacteria (47.3%, 9.5%, 5.4% and 1.3%, respectively), Firmicutes (1.4%), Actinobacteria (2.7%), Cyanobacteria (2.7%). The percentages of Proteobacteria and Bacteroides in seawater were greater than those in the groundwater from a non-seashore landfill, indicating a possible influence of seawater. Quite a few sequences had close relatives in marine or hypersaline environments. Many sequences showed affiliations with microbes involved in anaerobic fermentation. The remarkable abundance of sequences related to (per)chlorate-reducing bacteria (ClRB) in the groundwater was significant and worthy of further study.
基金Supported by Tianjin Application Basis and Advanced Technology Studied Plans(09JCYBJC08200)
文摘The mechanical dewatering of activated sludge is troublesome due to its high compressibility of solids. The dewatering can be enhanced dramatically by the use of electroosmosis,in which an electric field is applied to the sludge cake.In this study,the influence of filter cloth on the cathode on the dewatering of activated sludge was investigated.It was found that thicker filter cloth led to lower water removal from the sludge cake,so a stainless steel cathode net with small pore size instead of filter cloth was applied,which improves the dewatering efficiency and reduces the electric power consumption.Moreover,water absorbent materials were helpful to remove the water from the sludge cake.For the electroosmotic dewatering at 7 kPa and 24 V·cm-1,the water content in the sludge cake decreased to 60%(by mass) with the average 0.075 kW·h·kg-1of water removed by using the cathode net.
文摘Agro-chemical transport processes at different scales are discussed and relevant opening questions areidentified by literature review to make some suggestions concerning the improvement of research methods forfield scale solute transport by aid of evaluation of existing models, and examining transport behaviors of solutein vadose zones on different scales. The results indicate that present research progress and understanding onfield scale solute transport have not yet been enough to guarantee the use of our models for the management offield solute movement. Much more research work needs to be done, particularly, in aspects of high resolutionof spatial structures relevant to the hydraulic and transport properties, explicit numerical simulation of actualstructure on field scale and field measurement corroborated with model development.
