Hou D.,CAS Research Center for Eco Environmental Sciences |
Dai G.,Tsinghua University |
Wang J.,CAS Research Center for Eco Environmental Sciences |
Fan H.,Nanchang University |
And 2 more authors.
Desalination | Year: 2013
Boron removal and desalination from seawater by direct contact membrane distillation (DCMD) was studied with self-prepared polyvinylidene fluoride (PVDF) flat-sheet membrane. The membrane had an ultra-thin top skin and a porous network sponge-like layer and its effective pores showed a narrow distribution with a mean pore size of 0.22μm. The membrane exhibited good hydrophobicity and its contact angle was about 82.6±0.7°. During DCMD test of 35g/L sodium chloride solution, the maximum permeate flux can achieve 47.6kg/m2h. The natural seawater containing 4.65mg/L boron was treated by DCMD for simultaneous boron removal and desalination. Although the permeate flux decreased with concentration factor (CF) value increase, the permeate boron kept below 20μg/L and salt rejection was over 99.9%. When the CF value exceeded 4.0, there would be scale deposits formed, and the permeate quality and flux declined rapidly. The antiscalant polyacrylic acid could delay the deposit formation and the advisable dosage was 10mg/L. The membrane showed satisfying performance stability in a 300h continuous DCMD experiment even with the CF value as high as 7.0, indicating that the self-prepared membrane and DCMD process could be efficiently used for boron removal and desalination from seawater. © 2013 Elsevier B.V.
Xu H.-Z.,CAS Institute of Geology and Geophysics |
Li G.-M.,CAS Institute of Geology and Geophysics |
Zhang S.-Q.,Beijing Water Authority |
Dong Y.-H.,CAS Institute of Geology and Geophysics |
Li M.,CAS Institute of Geology and Geophysics
IAHS-AISH Publication | Year: 2011
Beijing is facing a serious water crisis because of an unprecedented economic and population boom. Two well fields were built in Pinggu basin, Beijing east, to ease the water pressure before water diversion of the South-to-North Water Diversion Project. In order to study the influence of the huge quantity of extraction in the Pinggu basin, a 3-D transient groundwater flow model was developed and several scenarios were simulated in the prediction periods. By analysing the simulation results, some useful conclusions were reached, which could be used for groundwater management and pumping strategies for the long-term sustainability of groundwater. Copyright © 2011 IAHS Press.
Zhang Z.,Hohai University |
Yuan Z.,Hohai University |
Kong L.,Hohai University |
Xia J.,Hohai University |
Zhu X.,Beijing Water Authority
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2010
In order to investigate the influence of field engineering on the nitrogen loss with runoff, the farmland comparative experiments, with different field ditche densities, were designed, and rainfall-runoff and nitrogen loss characteristics were studied. The results showed that compared to the treatment having more field ditches, the runoff sensitivity affected by the rainfall intensity with the treatment having less ditches was weaker, and the runoff peak lagged behind and the larger runoff lasted a longer time, the losses of total nitrogen reduced by 7.44%. Nitrate nitrogen and ammonia nitrogen losses were significant different between the two treatments. In early and peak stages of runoff process, ammonia nitrogen had a bigger proportion to total nitrogen than that at decline stage, while nitrate nitrogen's proportion had little change in the whole process. The loss of nitrogen loading was linearly related to the runoff. The field with more field ditches reduced water logging obviously, while the field with less field ditches reduced more total nitrogen losses.
Dai G.,CAS Institute of Botany |
Dai G.,Tsinghua University |
Wang B.,Tsinghua University |
Fu C.,Beijing Water Authority |
And 5 more authors.
Environmental Sciences: Processes and Impacts | Year: 2016
This study analyzed 15 pharmaceuticals and personal care products (PPCPs) in two rivers with different urbanization levels in the surrounding watershed (urban and suburb) in Beijing, China. Along the rivers, effluent samples from wastewater treatment plants (WWTPs) and wastewater samples from direct discharge outlets were also collected to reveal their possible contribution to the occurrence of PPCPs in these two rivers. Among the 15 PPCPs, 14 compounds were detected with caffeine (maximum 11 900 ng L-1) being the dominant compound. The total concentration of the detected PPCPs in direct discharge outlets (median 4706 ng L-1) was much higher than that in river waters (2780 ng L-1) and WWTP effluents (1971 ng L-1). The suburban-influenced Liangshui River had significantly higher PPCP concentrations compared to the urban-influenced Qing River due to more input of untreated wastewater from direct discharge outlets. Source apportionment showed that approximately 55% of the total PPCPs were contributed by untreated wastewater in the suburban-influenced river. Finally, ecological risk assessment has been regarded as a necessary part of general research. According to the environmental risk assessment results, caffeine, trimethoprim and metoprolol were found to be the most critical compounds, due to their high risk quotient values. The results of the present study can provide useful information for future PPCP pollution control and sustainable water management in Beijing, China. © The Royal Society of Chemistry 2016.
Lixi Z.,China Agricultural University |
Pengbo S.,Beijing Water Authority |
Fang J.,China Agricultural University |
Hengqing Q.,China Agricultural University |
And 4 more authors.
Earth Science Informatics | Year: 2014
Drought is a significant disaster in Beijing and it is important to find a method to assess the drought condition. First, this paper collected data of 85 soil monitoring stations in Beijing, such as soil dry bulk densities, saturated water contents, field capacities. Then, spatial variability characteristics of soil physics parameters were investigated by GIS and other three factors, 10 cm soil moisture content, organic matter and saturated water content which notably influenced soil moisture were extracted by Principal Component Analysis (PCA). Furthermore, four different nonlinear methods were put forward to predict crop-root zone soil water. 15555 single daily data from 2011 were used in parameters determination, while 15470 double daily data were used to test. The result showed that the Least Square Support Vector Machine coupling Particle Swarm Optimization Algorithm (PSO-LSSVM) (R 2 = 0. 875) did better than BP Neural Network (R 2 = 0. 840), Generalized Regression Neural Network (GRNN) (R 2 = 0. 850) and Wavelet Neural Network (WNN) (R 2 = 0. 853). As so the POS-LSSVM method was used to evaluate the drought conditions from October 2010 to March 2011 of Beijing, and the result showed that from October 2010 to January 2011, the drought conditions were getting increasingly worse while later relieved from January 2011 to March 2011. © 2013 Springer-Verlag Berlin Heidelberg.