Groundwater arsenic (As) contamination is a hot issue,which is severe health concern worldwide.Recently,many Fe-based adsorbents have been used for As removal from solutions.Modified granular natural siderite (MGNS),a...Groundwater arsenic (As) contamination is a hot issue,which is severe health concern worldwide.Recently,many Fe-based adsorbents have been used for As removal from solutions.Modified granular natural siderite (MGNS),a special hybrid Fe(II)/Fe(III) system,had higher adsorption capacity for As(III) than As(V),but the feasibility of its application in treating high-As groundwater is still unclear.In combination with transport modeling,laboratory column studies and field pilot tests were performed to reveal both mechanisms and factors controlling As removal by MGNS-filled filters.Results show that weakly acid pH and discontinuous treatment enhanced As(III) removal,with a throughput of 8700 bed volumes (BV) of 1.0 mg/L As(III) water at breakthrough of 10 mg/L As at pH 6.Influent HCO3^- inhibited As removal by the filters.Iron mineral species,SEM and XRD patterns of As-loading MGNS show that the important process contributing to high As(III) removal was the mineral transformation from siderite to goethite in the filter.The homogeneous surface diffusion modeling (HSDM) shows that competition between As(III) and HCO3^- with adsorption sites on MGNS was negligible.The inhibition of HCO3^- on As(III) removal was connected to inhibition of siderite dissolution and mineral transformation.Arsenic loadings were lower in field pilot tests than those in the laboratory experiments,showing that high concentrations of coexisting anions (especially HCO3^-- and SiO4^4-),high pH,low EBCT,and low groundwater temperature decreased As removal.It was suggested that acidification and aeration of high- As groundwater and discontinuous treatment would improve the MGNS filter performance of As removal from real high-As groundwater.展开更多
Significant advances in regional groundwater flow modeling have been driven by the demand to predict regional impacts of human inferences on groundwater systems and associated environment. The wide availability of pow...Significant advances in regional groundwater flow modeling have been driven by the demand to predict regional impacts of human inferences on groundwater systems and associated environment. The wide availability of powerful computers, user friendly modeling systems and GIS stimulates an exponential growth of regional groundwater modeling. Large scale transient groundwater models have been built to analyze regional flow systems, to simulate water budget components changes, and to optimize groundwater develop- ment scenarios. This paper reviews the historical development of regional groundwater modeling. Examples of Death Valley and Great Artesian Basin transient groundwater models are introduced to show the application of large scale regional groundwater flow models. Specific methodologies for regional groundwater flow modeling are descried and special issues in regional groundwater flow modeling are discussed.展开更多
Beijing, the capital city of China, has suffered from acute water shortage, with only 300 m3/a of water resources available per capita. In addition, Beijing has experienced a prolonged period of consecutive droughts f...Beijing, the capital city of China, has suffered from acute water shortage, with only 300 m3/a of water resources available per capita. In addition, Beijing has experienced a prolonged period of consecutive droughts from 1999 to 2010. Water crisis has constrained the socio-economic development of Beijing. Meanwhile, the national "South-to-North Water Transfer"（STNWT） project, which is expected to provide some relief to the water crisis in Beijing, is still under development. In order to ensure the security of water supply in Beijing before the completion of the STNWT project, several measures have been implemented to cope with droughts, including pumping groundwater from emergency well fields,water saving, recycling of water, rain and flood water harvesting, and the diversion of water from neighboring rivers and groundwater basins. Groundwater from four emergency well fields contributes the most to the public and domestic water supplies in Beijing, supplying a total volume of 1.8×10;m;.The water crisis is supposed to be mitigated by the completion of the STNWT project. After the completion of this project, more sustainable management of water resources will be implemented,including the use of aquifers as groundwater reservoirs and conjunctive use of surface water and groundwater resources.展开更多
基金financially supported by National Natural Science Foundation of China (Grant Nos.41672225 and 41222020)the Fundamental Research Funds for the Central Universities (Grant No.2652013028)the Fok Ying Tung Education Foundation, China (Grant No.131017)
文摘Groundwater arsenic (As) contamination is a hot issue,which is severe health concern worldwide.Recently,many Fe-based adsorbents have been used for As removal from solutions.Modified granular natural siderite (MGNS),a special hybrid Fe(II)/Fe(III) system,had higher adsorption capacity for As(III) than As(V),but the feasibility of its application in treating high-As groundwater is still unclear.In combination with transport modeling,laboratory column studies and field pilot tests were performed to reveal both mechanisms and factors controlling As removal by MGNS-filled filters.Results show that weakly acid pH and discontinuous treatment enhanced As(III) removal,with a throughput of 8700 bed volumes (BV) of 1.0 mg/L As(III) water at breakthrough of 10 mg/L As at pH 6.Influent HCO3^- inhibited As removal by the filters.Iron mineral species,SEM and XRD patterns of As-loading MGNS show that the important process contributing to high As(III) removal was the mineral transformation from siderite to goethite in the filter.The homogeneous surface diffusion modeling (HSDM) shows that competition between As(III) and HCO3^- with adsorption sites on MGNS was negligible.The inhibition of HCO3^- on As(III) removal was connected to inhibition of siderite dissolution and mineral transformation.Arsenic loadings were lower in field pilot tests than those in the laboratory experiments,showing that high concentrations of coexisting anions (especially HCO3^-- and SiO4^4-),high pH,low EBCT,and low groundwater temperature decreased As removal.It was suggested that acidification and aeration of high- As groundwater and discontinuous treatment would improve the MGNS filter performance of As removal from real high-As groundwater.
文摘Significant advances in regional groundwater flow modeling have been driven by the demand to predict regional impacts of human inferences on groundwater systems and associated environment. The wide availability of powerful computers, user friendly modeling systems and GIS stimulates an exponential growth of regional groundwater modeling. Large scale transient groundwater models have been built to analyze regional flow systems, to simulate water budget components changes, and to optimize groundwater develop- ment scenarios. This paper reviews the historical development of regional groundwater modeling. Examples of Death Valley and Great Artesian Basin transient groundwater models are introduced to show the application of large scale regional groundwater flow models. Specific methodologies for regional groundwater flow modeling are descried and special issues in regional groundwater flow modeling are discussed.
基金funding by Survey and evaluation of geological and mineral resources project: the Construction and Service of the National Groundwater and Land Subsidence Information System (No.DD2060299)
文摘Beijing, the capital city of China, has suffered from acute water shortage, with only 300 m3/a of water resources available per capita. In addition, Beijing has experienced a prolonged period of consecutive droughts from 1999 to 2010. Water crisis has constrained the socio-economic development of Beijing. Meanwhile, the national "South-to-North Water Transfer"（STNWT） project, which is expected to provide some relief to the water crisis in Beijing, is still under development. In order to ensure the security of water supply in Beijing before the completion of the STNWT project, several measures have been implemented to cope with droughts, including pumping groundwater from emergency well fields,water saving, recycling of water, rain and flood water harvesting, and the diversion of water from neighboring rivers and groundwater basins. Groundwater from four emergency well fields contributes the most to the public and domestic water supplies in Beijing, supplying a total volume of 1.8×10;m;.The water crisis is supposed to be mitigated by the completion of the STNWT project. After the completion of this project, more sustainable management of water resources will be implemented,including the use of aquifers as groundwater reservoirs and conjunctive use of surface water and groundwater resources.
