Measuring water resource use efficiency of the Dong Nai River Basin (Vietnam): an application of the two-stage data envelopment analysis (DEA)

Environment, Development and Sustainability - The recent growth of agriculture, industry and urban areas in Vietnam requires a large amount of water consumption as a production factor. This paper...     

Application of SWAT model to assess land use change and climate variability impacts on hydrology of Nam Rom Catchment in Northwestern Vietnam

Environment, Development and Sustainability - Land use and land cover (LULC) changes, climate variability and climate change (CC) contribute hydrological response in tropical catchments, but their...     

Esterification of sugarcane bagasse by citric acid for Pb2+ adsorption: effect of different chemical pretreatment methods

In this study, different pretreatment strategies of sugarcane bagasse prior to citric acid modification were investigated in terms of Pb²⁺ adsorption capacity. Pretreatment strategies included the use of NaOH, HCl, and C₂H₅OH in various concentrations. In order to fundamentally understand how these pretreatment methods affect the modification of sugarcane bagasse by citric acid as well as the Pb²⁺ adsorption capacity of sugarcane bagasse, three main components of sugarcane bagasse namely cellulose, hemicellulose, and lignin were isolated and esterified by citric acid under the same conditions. ATR-FTIR, XPS, SEM, and an analysis of the number of carboxylic acid groups were used to investigate the physicochemical and chemical properties of the materials. These three components were proved to participate in adsorption and induce the esterification with citric acid. Hence, pretreatment with ethanol and 0.01 M NaOH which could retain cellulose, hemicellulose, and lignin in sugarcane bagasse achieved a high Pb²⁺ adsorption capacity, i.e., 122.4 and 97 mg/g after the esterification with citric acid. In contrast, pretreatment with 0.5 M NaOH and 0.1 M HCl removed lignin and hemicellulose, leading to the lowest value of approximately 45 mg/g for citric acid esterified-pretreated sugarcane bagasse. XPS analysis and number of carboxylic group measurement confirmed the esterification between bagasse and citric acid. To understand the adsorption mechanism of adsorbent, two kinetic models including pseudo-first-order model and pseudo-second-order model were applied. The experimental data were well described by the pseudo-second-order model. The adsorption isotherm data were fitted Langmuir and Freundlich.

     

Status of water use and potential of rainwater harvesting for replacing centralized supply system in remote mountainous areas: a case study

Environmental Science and Pollution Research - The failure of the centralized water supply system forced XY community to become more dependent on uncertain and unstable water sources. The results...     

Photochemical Smog Modelling Using the Air Pollution Chemical Transport Model (TAPM-CTM) in Ho Chi Minh City,Vietnam

Environmental Modeling & Assessment - This paper describes the application of the air pollution model (TAPM-CTM) for photochemical airshed modelling in the Ho Chi Minh region. The model was...     

Analysis of recycling structures for e-waste in Vietnam

E-waste management in Vietnam poses real challenges such as the lack of specific e-waste legislation, the strong involvement of “craft villages” and the missing of monitoring data. Many issues (e.g., pollution level, generated waste, health of workers and resident living at recycling sites) lead to the limited access to these craft villages. Thus, there is no comprehensive picture on e-waste management in Vietnam available today. This research focuses on the current situation of e-waste management. Sources of e-waste, collection and treatment in Vietnam are investigated by utilizing most available sources of information (published journals, unpublished works from projects and reports from institutes, ministry) together with the interviewed data from experts, collectors, workers and especially, biggest traders in the field. Based on this information, the processes applied in Vietnam, both in the formal and informal sector, have been analyzed systematically in terms of inputs, outputs, potential emissions and related risks for workers. From these aspects, a comparison in terms of legal frameworks, collection and treatment at both formal and informal sector between Vietnam and other countries in Asian region was undertaken. Thus, major challenges of e-waste management and relatively comprehensive image of e-waste management and treatment in Vietnam have been identified.     

Climate change impacts on a large-scale erosion coast of Hai Hau district,Vietnam and the adaptation

Among the effects of global warming, sea level rise (SLR) and severe typhoons pose the greatest threat to the stability of human settlements along coastlines. Therefore, countermeasures must be developed to mitigate the influences of strong typhoons and persistent SLR for coastal protection. This study assesses climate change impacts on coastal erosion, especially in two projected SLR scenarios of RCP2.6 and RCP8.5. The results show that SLR and severe typhoons lead to the increase of coastal erosion, beach lowering and scour. Moreover, as in projected SLR scenarios, average waves in high tide can cause severe soil erosion at inner slopes and lead to dyke failure by 2060. The paper highlights the need for additional countermeasures to protect the coast of Hai Hau district against SLR and severe typhoons. Among the alternatives available for countering these threats, applying soil stabilization and soil improvement combined with geosynthetics are promising strategies for coastal structures. Hybrid structures can be used with earth reinforcement and soil improvement. Additionally, the paper emphasizes the importance of multiple protective adaptations, including geosynthetics and ecological engineering measures against climate change-induced severe erosion on the coast of Hai Hau district.     

PERCOLATION OF LEAD(II) AND CADMIUM(II) THROUGH TWO BENTONITES USED AS LANDFILL LINER

In order to prevent contamination of subsoil and groundwater by leachates containing heavy metals, montmorillonite linings are used on landfill bottoms. It is therefore important to understand ion uptake by this clay. In this study we have performed percolation of lead(II) and cadmium(II) through columns filled firstly with a technical bentonite and then with a reference bentonite. Elution curves provide an evaluation of metals retention. After the percolation step, columns are cut and metal ions are extracted to evaluate influence of side effects and soil depth on metal uptake. Moreover retentions of lead(II) and cadmium(II) are compared.     

Estimating the generation of recycled metals from obsolete motorcycles in Vietnam for ELV management

Journal of Material Cycles and Waste Management - The demand for various modes of transportation has significantly increased around the world due to rapid urbanization, the increase in population,...