EVALUATING FUTURE WATER QUALITY OF URBAN RIVERS IN HANOI UNDER EFFECT OF URBANIZATION AND CLIMATE CHANGE - THE APPLICATION OF WEAP MODEL FOR CAU BAY RIVER

Every day, up to 750,000 cubic meters of wastewater in Hanoi metropolitan areas is discharged directly into rivers and lake, of which only 10% is treated to the Vietnamese standards. According to the water drainage development master plan for the capital city of Hanoi until 2030, the government aim at dealing with flooding and improve environmental sanitation for local residents. With respect to the baseline and Master plan implementation scenarios, this study evaluates the future water quality of urban rivers in Hanoi under the effect of urbanization and climate change using Water Evaluation And Planning tool (WEAP) and take the Cau Bay catchment as the case study. The result shows that, without implementation of wastewater treatment plant, the water quality of Cau Bay River will be worse with the DO in dry season is 0.2-1.2 mg/l and BOD is 52.0-55.0 mg/l. With the implementation of Master plan, the level of DO and BOD would be 7.1-7.3 mg/l and 7.0-13.8 mg/l respectively in the dry season whereas the values are 3.7 mgO/l and 36.1-41.8 mg/l in the wet season. The degradation of wastewater during the wet season is results from the combine- overflow sewage system as designed in the master plan

The application of A/O-MBR system for domestic wastewater treatment in Hanoi: Research Article

The study aims to investigate an appropriate wastewater treatment process to treat domestic wastewater in Hanoi City which contain low-strength for COD (120-200 mg/L) but high in nitrogen content (10-40 mg/L). A lab scale anoxic-oxic system with a hollow fiber-Membrane Separation Bioreactor was operated at a flow rate of 5-10 L/h over a period of 150 days. The reactor was operated at different sludge recirculation rates. The MBR maintained relatively constant transmembrane pressure. During 150 days of reactor operation, treated water quality have COD of around 20 mg/L, NH4-N of less than 1 mg/L, NO3-N of less than 5 mg/L. The system shows good and stable efficiency for organic matter and nitrogen removal without adding an external carbon source and coagulants. The results based on the study indicated that the proposed process configuration has potential to treat the low-strength wastewater in Hanoi.Mục tiêu của nghiên cứu là đề xuất được một công nghệ hiệu quả và phù hợp để xử lý nước thải sinh họat ở các đô thị của Việt nam, là loại nước thải được thu gom từ hệ thống thoát nước chung có nồng độ chất hữu cơ thấp (COD 120-200 mg/l) nhưng hàm lượng chất dinh dưỡng như Nitơ, Phốt pho khá cao (T-N: 10-40 mg/L). Chúng tôi đã nghiên cứu và vận hành chạy thử mô hình xử lý sinh học yếm khí - kỵ khí (AO) kết hợp với màng vi lọc ở quy mô mô hình phòng thí nghiệm (công suất 5-10 L/h) ở các chế độ công suất bùn tuần hoàn khác nhau. Kết quả xử lý trong thời gian 5 tháng vận hành mô hình cho thấy chất lượng nước thải sau xử lý có hàm lượng COD nhỏ hơn 20 mg/L, NH4-N nhỏ hơn 1 mg/L, NO3-N nhỏ hơn 5 mg/L. Hiệu suất xử lý chất hữu cơ và chất dinh dưỡng rất ổn định và hệ thống không phải sử dụng các nguồn bổ sung chất hữu cơ hay các hóa chất trợ lắng như các công nghệ đang áp dụng. Kết quả cho thấy công nghệ AO kết hợp màng vi lọc có khả năng áp dụng thực tế, phù hợp với những nơi có quỹ đất nhỏ, chất lượng nước sau xử lý rất cao có thể phục vụ cho mục đích tái sử dụng

Fabrication and Magnetic Properties of Sintered SrFe12_{12}O19_{19}-NiFe2_{2}O4_{4} Nanocomposites

Two series of SrFe$_{12}$O$_{19}$/NiFe$_{2}$O$_{4}$ nanocomposite ferrites sintered in air at 850\rc{}C and 950\rc{}C were prepared using SrFe$_{12}$O$_{19}$ and NiFe$_{2}$O$_{4}$ nanopowders obtained via sol-gel method. The phase composition, surface morphology and magnetic properties of the composites were investigated using XRD, SEM and VSM respectively. For the SrFe$_{12}$O$_{19}$/NiFe$_{2}$O$_{4}$ ferrites with volume ratio ranging from 61 to 21 and sintered in 850$\r{}$C for 5 hours in air, all the specimens are composed of two phases but exhibit a typical single-phase magnetic behavior, indicating the existence of exchange coupling (EC) between the magnetically hard and soft phases. The value of coercivity H$_{c}$ decreases from 6.19 kOe to 0.574 kOe when volume of SrFe$_{12}$O$_{19}$ decreases from 6 to 1. While the samples with a mass ratio of $R_{m}$= SrFe$_{12}$O$_{19}$/ NiFe$_{2}$O$_{4}$ varying from 31 to 13 sintered in 950\rc{}C for 5 hours characterized with a ``bee waist'' type hysteresis loop. These results reveal that the magnetically hard and soft magnetic phases are not exchange- coupled. The saturation magnetization ($M_{S}$) increases from 36 emu/g to 43.3 emu/g when $R_{m}$ decreases from 31 to 13 and then decreases with $R_{m}= 12$ and 13

GROUNDWATER CONTAMINATION IN HANOI CITY DUE TO AMMONIA, ARSENIC, IRON AND ORGANIC MATTER

Joint Research on Environmental Science and Technology for the Eart

Factors affecting intention to purchase organic agriculture products among Vietnamese

Globally, customer intention to purchase has become the essential part of the product and organization's success in the market. More recently, the idea has captured the attention of academic and policymakers alike. Therefore, the current article analyses product quality features such as agreeableness, emotional stability conscientiousness, openness to experience and extroversion on the intention to purchase organic agricultural products in the context of Vietnam. The study also analyses the mediating role of customer satisfaction between the association of product quality features and intention to purchase organic products in Vietnam. The present study uses questionnaires to collect data pertaining to the health sector of Vietnam. The current study employs the smart-PLS to analyze the constructs and items' reliability as well as the association among constructs. The results show that product quality features except extroversion have a positive and significant association with intention to purchase organic products in Vietnam. The results also reveal that customer satisfaction significantly and positively mediates among the associations of product quality features and intention to purchase organic products in Vietnam. This study is suitable for policymakers while formulating policies that may directly or indirectly affect customers' intention to purchase organic agricultural products.Luong Thu Thuy (Faculty of Economics, Academy of Finance, Vietnam), Tran Thi Phuong Diu (Faculty of Economics, Academy of Finance, Vietnam), Nguyen Dinh Hoan (Faculty of Economics, Academy of Finance, Vietnam), Vu Viet Ninh (Faculty of Economics, Academy of Finance, Vietnam), Nguyen Thi Thuy Nga (Faculty of Economics, Academy of Finance, Vietnam)Includes bibliographical reference

Enhancement of Magnetic Properties of La-substituted Strontium Hexaferrite Particles Prepared by Sol-gel Route

La-substituted strontium hexaferrite particles Sr$_{1 - x}$La$_{x}$Fe$_{12}O_{19}$ $(x = 0 \div 0.2)$ were prepared by using sol-gel method and subsequent calcination at temperatures ranging from 750\rc{}C to 1050\rc{}C for 2h in air. The effects of the initial La concentration and the calcination temperature on the structure, particle morphology and magnetic properties of the hexaferrite samples were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The high magnetic coercivity $(_{i}H_{c}$) of 6.6 - 6.7 kOe and magnetization in maximum applied magnetic field (13.5 kOe) of 68 - 72 emu/g were achieved with the particles of compositions x = 0.1 $\div$ 0.2 and calcination temperatures between 850\rc{}C and 1000\rc{}C. The experimental data indicate that La replacement for Sr improves the crystallinity and inhibits the grain growth of the samples in a wide range of calcination temperature. These factors are important for production of high-coercivity hexaferrites by sol-gel technology

Spatial variations of arsenic in groundwater from a transect in the Northwestern Hanoi

Arsenic contamination of groundwater is a major health problem and has been a growing concern in the last decade in several regions of the world, especially in South and Southeast Asia, including the Red River delta, Vietnam. Regional groundwater studies have been carried out in the vicinity of Hanoi, on the banks of the Red River and its adjacent floodplains. In this study, the groundwater from a transect in the Northwestern area of Hanoi was examined. The results showed that 28.8% the wells of the B-B’ transect exceed the WHO guideline value for arsenic concentration in drinking water. The arsenic concentrations varied in a wide range from point to point, with the highest concentration found at Van Phuc and the lowest one found at Cam Yen. They also varied accordingly to the depth.References Anawar H.M., Akai J., Sakugawa H., Sakugawa H., 2004. Mobilization of arsenic from subsurface sediments by effect of bicarbonate ions in groundwater. Chemosphere, 54, 753-762. Appelo C.A.J., Postma D., 2004. Geochemistry, Groundwater and Pollution, second edition. Berg M., Tran H.C., Nguyen T.C., Pham H.V., Schertenleib R., Giger W., 2001. Arsenic contamination of groundwater and drinking water in Vietnam: A human health threat. Environmental Science Technology, 35(13), 2621-2626. Berg M., Stengel C., Pham T.K.T., Pham H.V., Sampson M.L., Leng M., Samreth S., Fredericks D., 2007. Magnitude of arsenic pollution in the Mekong and Red River Delta - Cambodia and Vietnam. Science of the Total Environment, 372, 413-425. Chowdhury U.K., Biswas B.K., Chowdhury T.R., Samanta G., Mandal B.K., Basu G.C., Chanda C.R., Lodh D., Saha K.C., Mukherjee S.K., Roy S., Kabir S., Quamruzzaman Q., Chakraborti D., 2000. Groundwater Arsenic Contamination in Bangladesh and West Bengal, India. Environmental Health Perpectives, 108(5), 393-397. Eiche E., Neumann T., Berg M., Weinman B., Van Geen A., Norra S., Berner Z., Pham T.K.T., Pham H.V., Stuben D., 2008. Geochemical processes underlying a sharp contrast in groundwater arsenic concentrations in a village on the Red River delta, Vietnam. Applied Geochemistry, 23, 3143-3154. Fendorf S., Michael H.A., Van Geen A., 2010. Spatial and temporal variations of groundwater arsenic in South and Southeast Asia. Science, 328, 1123. Doi: 10.1126/Science.1172974. General Statics Office of Vietnam, 2015. Regional statistics of Area, Population and Population density. McArthur J.M., Ravenscroft P., Safuilla S., Thirlwall M.F., 2001. Arsenic in groundwater: Testing pollution mechanisms for sedimentary aquifers in Bangladesh. Water Resources Research, 31(1), 109-117. Postma D., Larsen F., Nguyen T.M.H., Mai T.D., Pham H.V., Pham Q.N., Jessen S., 2007. Arsenic in groundwater of the Red River floodplain, Vietnam: Controlling geochemical processes and reactive transport modeling. Geochimica et Cosmochimica Acta, 71, 5054-5071. Postma D., Larsen F., Nguyen T.T., Pham T.K.T., Jakobsen R., Pham Q.N., Tran V.L., Pham H.V., Murray A.S., 2012. Groundwater arsenic concentrations in Vietnam controlled by sediment age. Nature GeoScience. Doi: 10.1038/NGEO1540. Smedley P.L., Kinniburgh D.G., 2002. A review of the source, behavior and distribution of arsenic in natural waters. Applied Geochemistry, 17, 517-568. Smedley P.L., 2006. Sources and distribution of arsenic in groundwater and aquifers. In T. Appelo (Ed.), Arsenic in Groundwater - A World Problem, 4-33. Van Geen A., Bostick B.C., Pham T.K.T., Vi M.L., Nguyen N.M., Dao M.P., Pham H.V., Radloff K., Aziz A., Mey J.L., Stahl M.O., Harvey C.H., Oates P., Weinman B., Stengel C., Frei F., Kipfer R., Berg M., 2013. Retardation of arsenic transport through a Pleistocene aquifer. Nature, 501, 204-208. Van Geen, A., Zheng Y., Versteeg R., Stute M., Horneman A., Dhar R., Steckler M., Gelman A., Small C., Ahsan H., Graziano J.H., Hussain I., Ahmed K.M., 2003. Spatial variability of arsenic in 6000 tube wells in a 25 km2 area of Bangladesh. Water Resources Research, 39(5), 1140. Doi:10.1029/2002WR001617. World Health Organization, 2011. Guidelines for drinking-water quality, fourth edition. Winkel L.H.E., Pham T.K.T., Vi M.L., Stengel C., Amini M., Nguyen T.H., Pham H.V., Berg M., 2011. Arsenic pollution of groundwater in Vietnam exacerbated by deep aquifer exploitation for more than a century. PNAS, 108(4), 1246-1251

GROUNDWATER CONTAMINATION DUE TO ARSENIC, IRON, AMMONIA, AND ORGANIC MATTER IN HANOI CITY, VIETNAM

Joint Research on Environmental Science and Technology for the Eart