A study was carried out to assess the water quality situation of groundwater sources in Kathmandu Valley, Nepal. Groundwater has remained to be a major water supply source for a population of 1.5 million at present in the valley. The focus of this study was to evaluate the extent and sources of groundwater contamination. Water sampling was carried out in selected deep wells and shallow sources. The level of pollution was evaluated by comparing the water quality results with WHO guidelines. The major problems with the dug wells, hand pumps and spouts were found to be the elevated nitrate and mercury contents. The deep wells located on the central aquifer were found to have a serious threat of ammonia pollution. Deep wells were also found to have iron, manganese and mercury concentrations exceeding the guideline values. Multivariate statistical analysis was carried out to cluster the sampling sources and identify the common factors describing the potential sources and possible mechanisms associated with the contaminants. The results suggested that disintegration of the sediment organic matter under strong reducing environment leads to the origin of the unusual water qualities at the central confined aquifer. This process may be microbially mediated and occurs with the simultaneous reduction of species such as arsenic, iron, manganese and sulfate. Both natural and anthropogenic water quality problems were observed in the groundwater system of Kathmandu valley. Attention should be focused to consider distinct strategies to address these problems.
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 đềxuất được một công nghệhiệu quảvà phù hợp đểxửlý nước thải sinh họat ởcác đô thịcủaViệt nam, là loại nước thải được thu gom từhệthốngthoát nước chung có nồng độchất 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 thửmô hình xửlý sinh học yếm khí-kỵkhí (AO) kết hợp với màng vi lọc ởquy mô mô hình phòng thí nghiệm (công suất 5-10 L/h) ởcác chếđộcông suất bùn tuần hoàn khác nhau. Kết quảxửlý trong thời gian 5tháng vận hành mô hình cho thấy chất lượng nước thải sau xửlý có hàm lượng COD nhỏhơn 20 mg/L, NH4-N nhỏhơn 1 mg/L, NO3-N nhỏhơn 5 mg/L. Hiệu suất xửlý chất hữu cơ và chất dinh dưỡng rất ổn định và hệthống không phải sửdụng các nguồn bổsung chất hữu cơ hay các hóa chất trợlắng như các công nghệđang áp dụng. Kết quảcho thấy công nghệAO kết hợp màng vi lọc có khảnăng áp dụng thực tế,phù hợp với những nơi có quỹđất nhỏ, chất lượng nước sau xửlý rất cao có thểphục vụcho mục đích tái sửdụng.
Solid waste management causes a significant challenge for the developing countries, especially in Vietnam. With the rapid development of Vietnam's economic and urbanization, the construction industry has gradually become one of pillar industries of the national economy in general and particularly Hanoi capital. While the construction industry has enjoyed continuous development, huge amounts of construction and demolition waste (CDW) being generated and dumped illegally on the vacant areas including roadsides, streets, and canals occur frequently. The consequences of improper waste management are potential alarming. With the rising concerns of waste management and global carbon concentrations, this research aims to evaluate the potential environmental impacts associated with CDW and to identify the best alternative in managing the CDW. Generally, the data are not homogeneous around the research area as the number of inhabitants is not constant nor it is the economic activity. There for if all the information is showed in thematic maps, the final waste management decisions can be made more efficiently. This study is performed with the aims of analysis on the current situation of CDW management in order to identify the environmental impacts related to CDW. Thereby, this research intended to be assessing CDW recycling potential and evaluating on the economic feasibility of the utilizing of recycled materials in the future. This paper combines the planning methodology to present the final results in thematic maps that make easier to interpret them. The results of the study would play the major role in developing a sustainable system such as assessing recycling potential, choosing appropriate treatment options, or operating solid waste management system.
Steel slag is an industrial by product of steel manufacturing processes and has been widely used in countries like Japan, United States, and European Union nations. However, the current utilization of steel slag in Vietnam is very low mainly because of lack of quality control of slag treatment and chances for reuse of treated steel slag. This paper presents the current steel slag production status and its potential to use as road construction aggregates in consideration of environmental and quality control issues. The basic oxygen furnace (BOF) and electric arc furnace (EAF) slag samples were collected from the seven large steel making factories of Vietnam and brought back to evaluate leaching amount from the slags. The batch leaching test methods were performed at laboratory using the leaching test of steel slag roadbed material in Japan (JIS K 0058 − 1) and Toxicity Characteristic Leaching Procedure (EPA method 1311) widely adopted in Vietnam. The results show that pH level and parameters such as T-Cr, Ni, Cu, Pb, As, Mn differ from the two test methods. The EPA 1311 seems too harsh to evaluate the environmental impacts because in the operation condition of the road, acidic liquid is absent. It is concluded that JIS test, which uses fresh water with gentle mixing not to degradation in size while leaching, is suitable for the evaluation, for the environmental assessment in service of the slag aggregate for roadbed.
Steel slag is an industrial by product of steel manufacturing processes and has been widely used in countries like Japan, United States, and European Union nations. However, the current utilization of steel slag in Vietnam is very low mainly because of lack of quality control of slag treatment and chances for reuse of treated steel slag. This paper presents the current steel slag production status and its potential to use as road construction aggregates in consideration of environmental and quality control issues. The basic oxygen furnace (BOF) and electric arc furnace (EAF) slag samples were collected from the seven large steel making factories of Vietnam and brought back to evaluate leaching amount from the slags. The batch leaching test methods were performed at laboratory using the leaching test of steel slag roadbed material in Japan (JIS K 0058 − 1) and Toxicity Characteristic Leaching Procedure (EPA method 1311) widely adopted in Vietnam. The results show that pH level and parameters such as T-Cr, Ni, Cu, Pb, As, Mn differ from the two test methods. The EPA 1311 seems too harsh to evaluate the environmental impacts because in the operation condition of the road, acidic liquid is absent. It is concluded that JIS test, which uses fresh water with gentle mixing not to degradation in size while leaching, is suitable for the evaluation, for the environmental assessment in service of the slag aggregate for roadbed.
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