Wastewater treatment is a process that is vital to protecting both the environment and human health. At present, the most cost-effective way of treating wastewater is with biological treatment processes such as the ac...Wastewater treatment is a process that is vital to protecting both the environment and human health. At present, the most cost-effective way of treating wastewater is with biological treatment processes such as the activated sludge process, despite their long operating times. However, population increases have created a demand for more efficient means of wastewater treatment, Fluidization has been demonstrated to in- crease the efficiency of many processes in chemical and biochemical engineering, but it has not been widely used in large-scale wastewater treatment. At the University of Western Ontario, the circulating fluidized-bed bioreactor （CFBBR） was developed for treating wastewater. In this process, carrier particles develop a biofilm composed of bacteria and other microbes. The excellent mixing and mass transfer characteristics inherent to fluidization make this process very effective at treating both municipal and industrial wastewater. Studies of lab- and pilot-scale systems showed that the CFBBR can remove over 90% of the influent organic matter and 80% of the nitrogen, and produces less than one-third as much biological sludge as the activated sludge process. Due to its high efficiency, the CFBBR can also be used to treat wastewaters with high organic solid concentrations, which are more difficult to treat with conventional methods because they require longer residence times; the CFBBR can also be used to reduce the system size and footprint. In addition, it is much better at handling and recovering from dynamic loadings （i.e., varying influent volume and concentrations） than current systems. Overall, the CFBBR has been shown to be a very effective means of treating wastewa- ter, and to be capable of treating larger volumes of wastewater using a smaller reactor volume and a shorter residence time. In addition, its compact design holds potential for more geographically localized and isolat- ed wastewater treatment systems.展开更多
Biologically produced surfactants （SACs） can mobilize and solubilize non-aqueous phase liquids （NAPL） adsorbed onto soil constituents. The interest in microbial surfactants has increased during recent years due to...Biologically produced surfactants （SACs） can mobilize and solubilize non-aqueous phase liquids （NAPL） adsorbed onto soil constituents. The interest in microbial surfactants has increased during recent years due to their lower toxicity, higher biodegradability, selectivity and specific activity under extreme conditions than synthetic SACs. Main output of the project represents preparation of this yeast biosurfactant intended for washing of matrices contaminated by NAPL. The influence of cultivation media composition on biosurfactant production was studied and basic properties （critical micelle concentration （CMC）, minimum surface tension） of isolated biosurfactants were compared with properties of synthetic surfactant with surface tension measurement. The interracial tension of the systems containing aqueous solutions of different concentrations and non-polar substances was measured with petroleum compounds （kerosene Jet A-l）, aromatic and aliphatic hydrocarbons （represented by toluene and hexane）. The solution of biosurfactant Yarrowia lipolytica （YAR） in the concentration range of 0-500 mg/L reduced interracial tension by 80% in all representative systems with model contaminants; biosurfactant Candida bombicola （CAN） was less efficient. Solubilization properties were proved with toluene and hexachlorocyclohexane （HCH） isomers alpha and gamma, and effective concentration of biosurfactants was determined as 100 mg/L for toluene and HCH. SACs produced by lipophilic yeast with non-toxic and non-pathogenic status （Yarrowia lipolytica, Candida sp., etc.） seem to be very promising. The results obtained will be used for the application of biosurfactants in the clean-up technologies as agents for the mobilization of non-polar contaminants as well as for stimulation of bioremediation processes.展开更多
Global economic development and increasing human activities have brought great challenges to fragile ecosystems.In order to avoid,reduce,and reverse desertification,Chinese and foreign scientists and ecological govern...Global economic development and increasing human activities have brought great challenges to fragile ecosystems.In order to avoid,reduce,and reverse desertification,Chinese and foreign scientists and ecological governance institutions have developed a series of ecological restoration technologies(ERTs)and models in the past few decades.These technologies can improve residents’livelihoods,strengthen disaster resilience,and launch a comprehensive review of degraded ecosystems in desertification regions.However,some studies and practices have limited the selection and promotion of good technologies and the assessments of these technologies,resulting in the waste and loss of funds and manpower.The objective of this study is to identify desertification control and restoration technologies and models,summarize the evolutionary features and trends of these technologies under different natural conditions,and evaluate the various ERTs that are now available.The data sources of this study include the databases of international organizations,CNKI,related literature and reports,and questionnaires from institutions and experts.First,the three stages of ERTs evolution were summarized,and the key events and social-economic developments were identified as the driving forces of evolution.Then,the four categories of ERTs were identified as biological,engineering,agricultural,and management ERTs.Finally,the key ERTs were evaluated in the five dimensions of the degree of difficulty,the degree of maturity,effectiveness,suitability,and potential for transfer.The management ERTs scores for the degree of difficulty,the degree of maturity,and potential for transfer are higher.This study provides a reference for adapting to local conditions,the comprehensive management,rational development,and utilization of dryland resources,improving the application of ecological technologies,and promoting the export and import of the excellent technologies.展开更多
文摘Wastewater treatment is a process that is vital to protecting both the environment and human health. At present, the most cost-effective way of treating wastewater is with biological treatment processes such as the activated sludge process, despite their long operating times. However, population increases have created a demand for more efficient means of wastewater treatment, Fluidization has been demonstrated to in- crease the efficiency of many processes in chemical and biochemical engineering, but it has not been widely used in large-scale wastewater treatment. At the University of Western Ontario, the circulating fluidized-bed bioreactor （CFBBR） was developed for treating wastewater. In this process, carrier particles develop a biofilm composed of bacteria and other microbes. The excellent mixing and mass transfer characteristics inherent to fluidization make this process very effective at treating both municipal and industrial wastewater. Studies of lab- and pilot-scale systems showed that the CFBBR can remove over 90% of the influent organic matter and 80% of the nitrogen, and produces less than one-third as much biological sludge as the activated sludge process. Due to its high efficiency, the CFBBR can also be used to treat wastewaters with high organic solid concentrations, which are more difficult to treat with conventional methods because they require longer residence times; the CFBBR can also be used to reduce the system size and footprint. In addition, it is much better at handling and recovering from dynamic loadings （i.e., varying influent volume and concentrations） than current systems. Overall, the CFBBR has been shown to be a very effective means of treating wastewa- ter, and to be capable of treating larger volumes of wastewater using a smaller reactor volume and a shorter residence time. In addition, its compact design holds potential for more geographically localized and isolat- ed wastewater treatment systems.
文摘Biologically produced surfactants （SACs） can mobilize and solubilize non-aqueous phase liquids （NAPL） adsorbed onto soil constituents. The interest in microbial surfactants has increased during recent years due to their lower toxicity, higher biodegradability, selectivity and specific activity under extreme conditions than synthetic SACs. Main output of the project represents preparation of this yeast biosurfactant intended for washing of matrices contaminated by NAPL. The influence of cultivation media composition on biosurfactant production was studied and basic properties （critical micelle concentration （CMC）, minimum surface tension） of isolated biosurfactants were compared with properties of synthetic surfactant with surface tension measurement. The interracial tension of the systems containing aqueous solutions of different concentrations and non-polar substances was measured with petroleum compounds （kerosene Jet A-l）, aromatic and aliphatic hydrocarbons （represented by toluene and hexane）. The solution of biosurfactant Yarrowia lipolytica （YAR） in the concentration range of 0-500 mg/L reduced interracial tension by 80% in all representative systems with model contaminants; biosurfactant Candida bombicola （CAN） was less efficient. Solubilization properties were proved with toluene and hexachlorocyclohexane （HCH） isomers alpha and gamma, and effective concentration of biosurfactants was determined as 100 mg/L for toluene and HCH. SACs produced by lipophilic yeast with non-toxic and non-pathogenic status （Yarrowia lipolytica, Candida sp., etc.） seem to be very promising. The results obtained will be used for the application of biosurfactants in the clean-up technologies as agents for the mobilization of non-polar contaminants as well as for stimulation of bioremediation processes.
基金The National Science Fundation of China(41977421)The National Key Research and Development Program of China(2016YFC0503700)。
文摘Global economic development and increasing human activities have brought great challenges to fragile ecosystems.In order to avoid,reduce,and reverse desertification,Chinese and foreign scientists and ecological governance institutions have developed a series of ecological restoration technologies(ERTs)and models in the past few decades.These technologies can improve residents’livelihoods,strengthen disaster resilience,and launch a comprehensive review of degraded ecosystems in desertification regions.However,some studies and practices have limited the selection and promotion of good technologies and the assessments of these technologies,resulting in the waste and loss of funds and manpower.The objective of this study is to identify desertification control and restoration technologies and models,summarize the evolutionary features and trends of these technologies under different natural conditions,and evaluate the various ERTs that are now available.The data sources of this study include the databases of international organizations,CNKI,related literature and reports,and questionnaires from institutions and experts.First,the three stages of ERTs evolution were summarized,and the key events and social-economic developments were identified as the driving forces of evolution.Then,the four categories of ERTs were identified as biological,engineering,agricultural,and management ERTs.Finally,the key ERTs were evaluated in the five dimensions of the degree of difficulty,the degree of maturity,effectiveness,suitability,and potential for transfer.The management ERTs scores for the degree of difficulty,the degree of maturity,and potential for transfer are higher.This study provides a reference for adapting to local conditions,the comprehensive management,rational development,and utilization of dryland resources,improving the application of ecological technologies,and promoting the export and import of the excellent technologies.
