Vietnam Journal of Science, Technology and Engineering最新文献

{"title":"Application of an innovative draw solute in forward osmosis (FO) processes","authors":"N. Nguyen, H. Nguyen, Shiao‐Shing Chen, X. Bui","doi":"10.31276/VJSTE.63(1).30-35","DOIUrl":"https://doi.org/10.31276/VJSTE.63(1).30-35","url":null,"abstract":": More attention is being paid to forward osmosis (FO) as a breakthrough technology to tackle environmental pollution due to advantages such as high contaminant removal and low energy consumption. Nevertheless, FO applications remain limited by the lack of ideal draw solutes that simultaneously achieve high permeate flux and low salt leakage flux. Therefore, this paper aims to increase water flux while maintaining low reverse salt diffusion by using a low concentration of a highly charged organic EDTA compound coupled with inorganic NaCl salt as a novel draw solute. Results of the FO performance revealed that a draw solute of 0.3 M EDTA-2Na mixed with 0.6 M NaCl yielded a higher water flux (J w =8.82 l/m 2 h) when compared to 0.9 M NaCl only (J w =7.61 l/m 2 h). Moreover, the FO-membrane distillation system produced good quality drinking water with a total dissolved solid (TDS) of <5 mg/l from the permeate stream originating from influent brackish water with a TDS of 6000 mg/l. The analysis results from scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDX) images observed a cake layer of NaCl on the FO membrane surface.","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89218810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diversity of zooplankton and benthic macroinvertebrates of estuarine coastal waters in Tien Giang province, southern Vietnam","authors":"Thuy Lan Chi Nguyen, T. Dinh, T. Dang, A. Pham, Thanh H. T. Nguyen, T. T. Huynh, N. Tran","doi":"10.31276/vjste.62(4).03-07","DOIUrl":"https://doi.org/10.31276/vjste.62(4).03-07","url":null,"abstract":": The Tien Giang province is located in the tropical climate zone of the Mekong delta. In this study, the diversity of zooplankton and benthic macroinvertebrates were investigated in the estuarine coastal waters of the Tien Giang province of southern Vietnam. 10 sites were observed over six time periods from 2019 (March, May, September, and November) and 2020 (March and May). The taxonomic richness, abundance, and diversity index were applied to this biodiversity assessment of the zooplankton and benthic macroinvertebrates. The results of the assessment showed that 30 species of zooplankton and 18 species of benthic macroinvertebrates were found in the study area. The density of zooplankton at each site ranged from 6 to 93 individuals/sample, while the density of benthic macroinvertebrates at each site fluctuated from 3 to 12 individuals/sample. The Shannon-Wiener diversity index of zooplankton fluctuated from 1.02 to 1.58 and that of the benthic macroinvertebrates ranged between 0.91 and 1.33. Besides, statistical analysis showed that the species richness of the zooplankton and benthic macroinvertebrates positively correlated with their density (r=0.2283-0.6423). This study contributes to the diversity information of zooplankton and benthic macroinvertebrates, which can be used to position the sustainable management of natural resources and evaluate the natural feed sources for aquaculture in this estuarine area.","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75843543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flood inundation mapping using Sentinel-1A in An Giang province in 2019","authors":"T. Nguyen, Trung Chinh Nguyen, T. Nguyen, T. Doan","doi":"10.31276/vjste.62(4).36-42","DOIUrl":"https://doi.org/10.31276/vjste.62(4).36-42","url":null,"abstract":"a given flood event. Apart from initial studies, several research works have concentrated on improving estimation accuracy [11-14]. Review articles [15, 16] are also available. Since the mid Abstract: An Giang is one of the provinces in the Mekong delta that is greatly affected by flood events, which brings damage and devastation to life and property. This study practices the application of Sentinel-1A images to monitor the distribution of flood depths in the An Giang province in 2019 as well as applies regression correlation and thresholding to scattering value analysis. The research results indicated the exponential regression model on the VV polarization images had correlation coefficients (r) in August, September, and October ranging from 0.8398 to 0.9764 and determination coefficients (R 2 ) ranging from 0.7896 to 0.9533. Results from the map of current flood depth showed that the flood depth ranged from 0-250 cm, which corresponded to four flood levels. The flood area increased from August to October with the largest flooded area being 89,606.82 ha (accounting for 26.15%) mainly on rice lands and in eight urban districts including An Phu, Tinh Bien, Chau Thanh, Chau Phu, Phu Tan, Tri Ton, Chau Doc, and Long Xuyen city. The limit of flood depth determined by using the Sentinel-1A images was below 145 cm. Above this value, the scattering in the image is not significantly different from the actual submerged depth.","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"73 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82129116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of phosphorus release from alluvial sediments using single extraction: a case study in Can Gio, Southern Vietnam","authors":"T. Tran, T. T. Ngo, Ngoc Tuyen Nguyen, Bich Chau Tran, M. Truong","doi":"10.31276/vjste.62(4).60-64","DOIUrl":"https://doi.org/10.31276/vjste.62(4).60-64","url":null,"abstract":"some work has been done to understand the behaviour of nutrients in the Can Gio mangrove Abstract: Sediment-water interaction is a complicated process; hence, it is essential to know the potential mobility of an element from sediment to the aquatic environment. In this study, the potential mobility of phosphorus (P) in sediment from Can Gio was investigated. Three single extractions were applied including a mild salt (NH 4 Cl), an acid (HCl), and a base (NaOH) each representing different environmental factors during sediment resuspension. Other geochemical parameters were also determined. The total amount of P in the sediments varied from 320.41 mg/kg to 668.22 mg/kg in five sampling sites. The general range of potential mobility of P decreased as follows: P-mild (3.70-13.13 mg/kg) < P-base (36.80-78.53 mg/kg) < P-acid (133.85-380.57 mg/kg). Although P-acid was not easily released to the environment, its relatively high concentration can affect the aquatic environment when the environment becomes acidic.","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"10 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72619250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using a numerical model with moving boundary conditionsto study the bed change of a Mekong river segment in Tan Chau, An Giang, Vietnam","authors":"Kim Loan Tran Thi, Huy Nguyen Quoc, Phung Nguyen Ky, B. N. Thi","doi":"10.31276/vjste.62(4).49-59","DOIUrl":"https://doi.org/10.31276/vjste.62(4).49-59","url":null,"abstract":"Abstract","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"40 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91433940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pectin bioplastic films regenerated from dragon fruit peels","authors":"Thi-Cam-Trang Truong, Takaomi Kobayashi","doi":"10.31276/vjste.62(4).18-22","DOIUrl":"https://doi.org/10.31276/vjste.62(4).18-22","url":null,"abstract":"According to the organization European Bioplastics, bioplastics are defined as materials based on renewable resources or those that are biodegradable or compostable [3]. Bio-based plastics are made from polysaccharides such as starches, cellulose, chitin, pectin, proteins like wheat gluten, wool, silk, gelatin, lipids (animal fats), vegetable oils, and products of microorganisms. Pectin is a natural material that appears in a great proportion of fruits and vegetables such as berries, apples, and oranges. Pectin is a mandatory polymer and its use in industry has diverse applications that continues to grow [2]. Pectin is a necessary component in plant cell structure and it consists of α-(1, 4)-linked D-galacturonic acid residues in which a part of the galacturonic acid is esterified or an acetylated methyl or both [4]. Depending on the degree of esterification (DE), pectin is divided into high-methoxyl (HM) pectin (DE>50%) and low-methoxyl (LM) pectin (DE<50%) [5]. Pectin extraction is typically performed by way of solvent extraction from raw materials where all extraction conditions, such as extraction temperature, extraction time, pH, and type of extraction solvent can affect the yield and quality of extracted pectin [4]. Normally, solvents with strong hydrogen bonding capacity are good for polysaccharides [6], which could promote carbohydrate chain spreading. Pectin molecules with a completely extended structure in a good solvent have better steric impediment, which stands in the way of intermolecular flocculation. Pectin has attracted a lot thanks to its exceptional properties; they are able to freeze in the presence of acids and sugars, have a high viscosity, are Pectin bioplastic films regenerated from dragon fruit peels","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83151533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing existing surface water supply sources in the Vietnamese Mekong delta: case study of Can Tho, Soc Trang, and Hau Giang provinces","authors":"D. Dinh, T. L. Nguyen, T. Nguyen, H. Nguyen","doi":"10.31276/vjste.62(4).65-70","DOIUrl":"https://doi.org/10.31276/vjste.62(4).65-70","url":null,"abstract":"The VMD, home to over 21 million people, is a part of the Mekong delta that covers an area of approximately 3.9 million hectares with a dense maze of canals and rivers [1]. Water plays a significant role in strategies for economic growth for the region in general and specifically for the provinces of Can Tho, Hau Giang, and Soc Trang [2]. Nonetheless, in recent years, the impacts of climate change and sea level rise are serious threats as they cause extreme phenomena such as salinity intrusion and severe droughts [3, 4]. These negative effects on water supply security in the delta creates possible threats to water supply systems. While groundwater is widely used in coastal areas, surface water is still a primary source of water in the provinces. However, the substantial extraction of groundwater for domestic use causes delta-wide subsidence that necessarily restricts excessive groundwater extraction [5, 6], therefore, the probability of switching to surface water needs to be taken into account. Rivers and canals in this region are usually considered as surface water resources for water supply systems. Nevertheless, the degradation of surface water quality due to pollution from anthropogenic activities has also limited the availability of surface water for domestic use in these provinces [7]. Assessing the water quality from the rivers and canals therefore is an important part of identifying acceptable areas for surface water supply abstraction to support water supply management. Currently, most water treatment plants in the VMD experience low capability of desalination followed by expensive construction and operation costs [8, 9]. Meanwhile, salinity is a significant criterion for the selection of water sources. Selected water sources are characterized by low frequency of salinity. Geographic Information System (GIS) software has continually demonstrated very informative spatial analyses in water monitoring research that supports water supply management. This paper aims to evaluate existing salinity and surface water quality in Can Tho, Hau Giang, and Soc Trang provinces, thereby building effective strategies and providing support to water utilities for water supply security in the context of climate change and local human activities. Assessing existing surface water supply sources in the Vietnamese Mekong delta: case study of Can Tho, Soc Trang, and Hau Giang provinces","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77809876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Single and combined effects of Di-2-ethylhexyl phthalate and bisphenol A on life traits of the tropical micro-crustacean Ceriodaphniacornuta","authors":"V. Nguyen, Manh-Ha Bui, Emilie Strady, Thuy-Chung Kieu-le, Ba-Trung Bui, T. Dao, Ho Chi Minh city Vietnam Resources","doi":"10.31276/vjste.62(4).23-29","DOIUrl":"https://doi.org/10.31276/vjste.62(4).23-29","url":null,"abstract":": Plastics, plastic additives, and their emission have attracted significant attention and concern both socially and scientifically. Di-2-ethylhexyl phthalate (DEHP) and bisphenol A (BPA) are two of the many plastic additives widely found in aquatic environments, which can have severe impacts on aquatic animals like micro-crustaceans. Therefore, this study assessed the chronic effects of DEHP and BPA, both individually and jointly, at environmental concentrations (e.g. 50 and 500 µg/l) on the survival rate, reproduction, and growth of the tropical micro-crustacean Ceriodaphnia cornuta . We found that each of the two plastic additives, and a mixture of the two, had some influence on the survivorship of C. cornuta . While DEHP marginally enhanced the reproduction of the animals, BPA strongly inhibited it. Additionally, the mixture of DEHP and BPA caused a synergistic effect on reproduction but an antagonistic effect on the growth of C. cornuta . Both DEHP and BPA induced a significantly longer body of C. cornuta when exposed to these plastic additives. Our results showed that the tropical micro-crustacean C. cornuta is more sensitive to DEHP and BPA than the temperate micro-crustacean D. magna in relation to body length development and reproductive characteristics. Our findings enrich the knowledge of DEHP and BPA toxicity to tropical micro-crustaceans. Besides, our results are also of significant value to freshwater monitoring and environmental risk assessments of plastic additives.","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73997896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Removal of methylene blue from simulated wastewater by Carica papaya wood biosorbent","authors":"Thi Nhu Tuyen Nguyen, T.M.H. Huynh, T. To","doi":"10.31276/vjste.62(4).08-17","DOIUrl":"https://doi.org/10.31276/vjste.62(4).08-17","url":null,"abstract":"Dye application occurs in several industries such as the textile, paper and pulp, paint, printing, rubber, and cosmetics industries. During the dyeing process, 1-15% of the dye is lost in the effluent discharge that generates endless quantities of dye-containing wastewater [1]. Synthetic dyes, characterized by complex aromatic structures, are stable enough to withstand heat and light and are considered nonbiodegradable [2, 3]. Discharge of these dyes into effluent may impart toxicity to aquatic life and may be carcinogenic or mutagenic to human beings, which causes serious damage such as dysfunction of the kidneys, reproductive system, liver, brain, and central nervous system [4-6]. Methylene blue (MB) is a cationic dye that is widely used in dyeing cotton, wool, coloured paper, and coatings for paper stocks [7]. Table 1 represents the general characteristics of methylene blue.","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74721957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microbiological contamination of indoor air in university classrooms(Case study: University of Science - Vietnam National University,Ho Chi Minh city)","authors":"Diep Yen Nga Dang, H. Vuong, Thị Tâm Nguyễn, Thi Thanh Thao Phan","doi":"10.31276/vjste.62(4).30-35","DOIUrl":"https://doi.org/10.31276/vjste.62(4).30-35","url":null,"abstract":"In recent years, indoor air pollution has been of increasing interest to scientists as well as environmental management authorities as most people are indoors about 80-90% of their time [1, 2]. Hence, indoor air quality is of greater significance to human health due to the greater exposure time of indoor air than outdoor air. An average person inhales around 6-10 l/min and needs 15 m3 of air per day [3]; thus, it is critical that indoor air be studied and evaluated. According to research by the United States Environmental Protection Agency (USEPA), indoor air pollution is one of the top five public health risks [4] contributing to an increase in the likelihood of cardiovascular diseases, lung diseases, and respiratory diseases [5].","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"67 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76770243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}