Van, Thien Nu ThaiDang, Hung VietNguyen, Hoa Thi Thanh
Science & Technology Development Journal - Science of The Earth & Environment; Vol 2 No 2 (2018); 5-11 (29 May 2019)
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Anaerobic and anoxic variations were combined with membrane bioreactor to form an Anaerobic/Anoxic configuration in MBR-based (Ana-Ano-MBR) system for improving the system performance in terms of organic degradation and nutrient removal from brewery wastewater. The model of Ana-Ano-MBR system made from polyacrylic with the capacity of 42 liters was operated with organic loading rate of 0.75 kgCOD/m3.day. The results showed that for the nitrate recycling ratios of 100, 200, 300%, average NH4+-N and TN removal efficiencies of the model were 95.1 and 76.6, 98.5 and 89.6, 98.9 and 90.2%, respectively, and the output values of NH4+-N and TN were within the limits of Vietnam National Standards (QCVN 40:2011/BTNMT, column A). Treatment efficiencies of COD and TP were over 90% and below 60%, respectively, during the whole experiment period. Low phosphorus removal efficiency was the drawback of Ana-Ano-MBR system due to the lack of appropriate system configuration and operational conditions for PAOs’ growth and activity.
La, Ha Thi ThaiChau, Mai Ngoc
Science & Technology Development Journal - Science of The Earth & Environment; Vol 2 No 2 (2018); 12-18 (29 May 2019)
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Polymer deriving from nature as Chitosan, which is one of the most abundant natural polymers in the world has effectively antibacterial potentiality. However, chitosan is relatively difficult for applications due to its disadvantageous properties. In this article, modifying chitosan (CS) is the grafting copolymerization using monomer n-butyl acrylate (BA) and tert-butyl hydroperoxide (TBHP) as an initiator. This process purposes to attain product having lower glass transition temperature (Tg) than original chitosan causing a wide range of applications but still keeping the capability of being an excellently antibacterial agent. The effects of parameters on synthesizing copolymer were studied by determining the grafting percentage (G%) and grafting efficiency (E%). The results revealed that the highest G = 242% and E = 61% were obtained at the conditions as following: BA/CS = 4 w/w, TBHP/CS = 5 v/w with [TBHP] = 20mM, [CS] = 0.75% w/v in acetic acid 0.6% and reaction temperature 90°C in 6 hours.
Le, Trung VanNguyen, Co Tang
Science & Technology Development Journal - Science of The Earth & Environment; Vol 2 No 2 (2018); 19-25 (29 May 2019)
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Permanent Scatterer InSAR (PSInSAR) technique is used commonly to evaluate land subsidence for some cities in the world and the pilot project in Ho Chi Minh City has shown the capability of this technique for mapping land subsidence in the period from 2006 to 2010. The result shows that PSInSAR can be applied to study the land subsidence phenomenon more efficiently than any traditional methods. However, SAR data often are commercial images such as ERS, ALOS, COSMO SkyMed… that a large number of SAR scenes must be collected to ensure the best results. This paper introduces results of the average subsidence velocities in Ho Chi Minh City that PSInSAR technique is applied to process SAR data from Sentinel-1 and COSMO SkyMed satellite. Evaluating the preliminary result showed that the capacity of using free Sentinel-1 images to replace commercial images for monitoring land subsidence.
Ho, Dung MinhHo, Bang QuocLe, Thang Viet
Science & Technology Development Journal - Science of The Earth & Environment; Vol 2 No 2 (2018); 26-37 (29 May 2019)
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Livestock is one of the main activities of the agricultural sector in Tan Thanh district, Ba Ria – Vung Tau province. Beside of pollution sources such as waste water, solid waste, livestock activity in Tan Thanh district, Ba Ria - Vung Tau province in recent years has caused air pollution in the livestock area and surrounding area. This research was carried out to evaluate the process of air pollution dispersion from livestock activities based on applying the TAPM meteorological model and AERMOD air quality model. The results showed that the maximum concentrations of air pollutants from livestock area such as NH3, H2S and CH3SH exceeded the National Technical Regulation on Ambient Air Quality (average hour) in the centre of Tan Thanh district, such as Toc Tien commune, part of Tan Phuoc and Phuoc Hoa communes, is 505 μg/m3; 57.4 μg/m3 and 111 μg/m3, respectively. Phu My district and other suburban communes (Hac Dich, Song Xoai, Chau Pha, Tan Hoa, Tan Hai, My Xuan, etc.) have distribution of lower concentrations of air pollutants. Base on the present results of modeling, the authors have proposed livestock development scenarios to control air pollution from this activity, contributing to environmental protection for Tan Thanh district.
Phung, Sy ChiTrinh, Tu Cong
Science & Technology Development Journal - Science of The Earth & Environment; Vol 2 No 2 (2018); 38-49 (29 May 2019)
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The results of surveys, investigation and assessment show that the climate conditions of dipterocarpaceae forests are relatively suitable for the growth and development of rubber trees. However, there are some rather severe indicators such as seasonal rainfall distribution, low humidity, inundation in rainy season and drought in the dry season; High and low temperatures reach the limit for the requirement of rubber trees. Most of dipterocarpaceae forest area consists of sandy or sandy soil, discrete soil texture, poor humus, poor water and nutrient retention, rapid heat absorption and transfer, at depths away from the surface of 20 - 40 cm is tombstone and gravel layer, under the clay, easily cause local inundation in the rainy season. The proportion of dipterocarpaceae forest land, which suitable for rubber trees is quite low, with the majority of adaptation levels S2 and S3, no suitable area at S1 level. In the first 2 years, the growth of rubber trees in dipterocarpaceae forest is less than that of rubber in upland fields, cleared land from evergreen forest, semi-evergreen forest. From the third year onwards, the difference in expression is clearer, in that the rubber tree’s diameter on the soil of the dipterocarpaceae forest is lower than that of the traditional rubber plantation at the same age.
Nguyen, Vu NguyenLe, Trung VanTran, Van Thi
Science & Technology Development Journal - Science of The Earth & Environment; Vol 2 No 2 (2018); 50-56 (29 May 2019)
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Saline intrusion reduces crop productivity, causes land degradation, decreases water quality, and severely affects agricultural production, the environment as well as livelihoods. Under the evolution of climate change and human activities from the upstream of the Mekong, the downstream areas of Dinh An and Cung Hau estuaries in Tra Vinh province are also significantly affected by saline intrusion from the East Sea. This article presents the integrated solution of remote sensing and GIS in monitoring and mapping salinity intrusion. The data used are Landsat 8 satellite images combined with salinity water monitoring data collected from actual observation stations during the dry season. Analysis showed that there was a statistically significant correlation between the observed salinity value of the water and the pixel value of the first principal component image. Simulation of spatial distribution from the study indicates that saline intrusion is now entering the interior with a distance from the estuary to about 30 - 48 km depending on the time of the dry season. The results of this study will assist managers in planning food safety strategies at the risk of saline intrusion.
Nguyen, Hung ThanhTon, Anh Nu PhuongNguyen, Hang Thi Cam
Science & Technology Development Journal - Science of The Earth & Environment; Vol 2 No 2 (2018); 57-67 (29 May 2019)
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Surface water sources in Ho Chi Minh City (HCMC) are being exploited for various purposes such as water supply for daily life, industry and services ; irrigation, animal husbandry, aquaculture ; navigation, environmental landscaping, waste reception and assimilation, etc. Each of these uses has its own benefits and values. However, up to now, the economic value of these water resources has not been fully appreciated and evaluated objectively. This paper presents an overview of the economic value of water resources and the economic valuation of some of the typical value types used in HCMC by 2016, including use for living, industrial, service, irrigation, transportation and environmental landscape.
Pham, Phu XuanNguyen, De Ngoc
Science & Technology Development Journal - Science of The Earth & Environment; Vol 2 No 2 (2018); 68-79 (29 May 2019)
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This research was carried out to systematize and assess the appropriateness of farmer’s indigenous knowledge and their ability adapt with the flood in An Giang province, results of the research will provide a scientific foundation for proposing solutions to conserve and enhance the use of indigenous knowledge in reducing the vulnerability of people living in flooded areas. The results showed that local people used several effective indigenous knowledges for adapting with floods. However, the valuable indigenous knowledge has not been recorded yet, nor documented in written materials for sharing to young generations and communities; some indigenous practices are not suitable with the current requirement for flood adapation strategies. Research results showed that (LVI) of diffirent Zone (upper zone, middle zone, lower zone) are decreasingly dependent on major components of social networks, knowledge and skills, natural resources, finance and incomes, livelihood strategies, natural disater and climate variability. In which, (LVI: 0.390) of Phu Huu commune in An Phu district which locates in the upper zone is higher than LVI of two communes located in the lower part of the river. These communes are Vinh An commune (LVI: 0.287), Chau Thanh district (middle zone) and Vinh Phuoc commune (LVI: 0.331), Tri Ton district (lower zone) and adaptive capacity of Phu Huu commune (0.399) is also higher than Vinh An (0.299) and Vinh Phuoc (0.337). It reflects the direct proportion between LVI and adaptive capacity. The research also suggests some solutions to conserve the valuable indigenous knowledge in adapting to climate change of local people.
Hoang, Thu TrangDao, Khoi NguyenPham, Loi ThiNguyen, Hong Van
Science & Technology Development Journal - Science of The Earth & Environment; Vol 2 No 2 (2018); 80-88 (29 May 2019)
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The objective of this study was to analyze the changes of riverbanks in Ho Chi Minh City for the period 1989-2015 using remote sensing and GIS. Combination of Modified Normalized Difference Water Index (MNDWI) and thresholding method was used to extract the river bank based on the multi-temporal Landsat satellite images, including 12 Landsat 4-5 (TM) images and 2 Landsat 8 images in the period 1989-2015. Then, DSAS tool was used to calculate the change rates of river bank. The results showed that, the processes of erosion and accretion intertwined but most of the main riverbanks had erosion trend in the period 1989-2015. Specifically, the Long Tau River, Sai Gon River, Soai Rap River had erosion trends with a rate of about 10.44 m/year. The accretion process mainly occurred in Can Gio area, such as Dong Tranh river and Soai Rap river with a rate of 8.34 m/year. Evaluating the riverbank changes using multi-temporal remote sensing data may contribute an important reference to managing and protecting the riverbanks.
Nguyen, Hung ThanhTon, Anh Nu PhuongNguyen, Hang Thi Cam
Science & Technology Development Journal - Science of The Earth & Environment; Vol 2 No 2 (2018); 89-96 (29 May 2019)
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Water is essential to life, making its total economic value immeasurable. At the same time water is a finite resource, and one for which competition is likely to increase as the Ho Chi Minh City’s economy grows. Driven by this heightened competition, the economic value of water will rise, and decision-makers in both the private and the public sectors will need information that can help them maximize the benefits derived from its use. This report is an initial step toward (1) raising awareness of water’s importance to our city economic welfare, and (2) assembling information that is critical to sustainably managing the city’s water resources. It emphasizes the analysis of the contribution of two important inputs to economic sectors: labor and water use; calculate the index of economic water productivity and show the necessary interventions in the face of water shortage.