Review on membrane module configurations used for membrane distillation process

Nowadays, with the salient advantages of the seawater desalination process, membrane distillation (MD) technology has received increased interests to achieve desalination application. As a heat-based technology, by using the hydrophobic membrane, MD provides high efficiency in the desalination process of seawater, RO water and other solutes with high concentrations of dissolved solids. Besides, this is an alternative technology to significantly reduce the environmental impacts of traditional desalination technologies commonly used, such as distillation or reverse osmosis. In many factors affecting the desalination capacity of the membrane distillation system, membrane module configuration has a strong influence in evaluating the economic and technical efficiency of the technology. This review aims to assess the suitability of MD technology under different perspectives on the current types of membrane module configurations that include flat sheet, tubular, hollow fibre and spiral wound membranes. In addition, the evaluation of the advantages and disadvantages of the membrane module configurations will guide further studies to improve the shortcomings of existing MD technologies

The Endo-α(1,4) Specific Fucoidanase Fhf2 From Formosa haliotis Releases Highly Sulfated Fucoidan Oligosaccharides

Fucoidanases are endo-fucoidanases (also known as endo-fucanases) that catalyze hydrolysis of α-glycosidic linkages in fucoidans, a family of sulfated fucose-rich polysaccharides primarily found in the cell walls of brown seaweeds. Fucoidanases are promising tools for producing bioactive fucoidan oligosaccharides for a range of biomedical applications. High sulfation degree has been linked to high bioactivity of fucoidans. In this study, a novel fucoidanase, Fhf2, was identified in the genome of the aerobic, Gram-negative marine bacterium Formosa haliotis. Fhf2 was found to share sequence similarity to known endo-α(1,4)-fucoidanases (EC 3.2.1.212) from glycoside hydrolase family 107. A C-terminal deletion mutant Fhf2∆484, devoid of 484 amino acids at the C-terminus, with a molecular weight of approximately 46 kDa, was constructed and found to be more stable than the full-length Fhf2 protein. Fhf2∆484 showed endo-fucoidanase activity on fucoidans from different seaweed species including Fucus evanescens, Fucus vesiculosus, Sargassum mcclurei, and Sargassum polycystum. The highest activity was observed on fucoidan from F. evanescens. The Fhf2∆484 enzyme was active at 20–45°C and at pH 6–9 and had optimal activity at 37°C and pH 8. Additionally, Fhf2∆484 was found to be calcium-dependent. NMR analysis showed that Fhf2∆484 catalyzed hydrolysis of α(1,4) linkages between L-fucosyl moieties sulfated on C2 (similar to Fhf1 from Formosa haliotis), but Fhf2∆484 in addition released oligosaccharides containing a substantial amount of 2,4-disulfated fucose residues. The data thus suggest that the Fhf2∆484 enzyme could be a valuable candidate for producing highly sulfated oligosaccharides applicable for fucoidan bioactivity investigations

Space law in Vietnam: outer space policy, legal development and its future pathway

Chociaż Wietnam uczestniczył w licznych operacjach kosmicznych, współpracując z wieloma narodami z całego świata, prawna regulacja sektora kosmicznego jest wciąż w powijakach. W artykule przedstawiono rozwój polityki i prawa kosmicznego, a także współpracy międzynarodowej w zakresie wykorzystania przestrzeni kosmicznej w Wietnamie od 1979 roku do chwili obecnej, z punktem zwrotnym w 2006 roku. Autorzy wskazali także kilka prognoz dotyczących przyszłej ścieżki wietnamskiego prawa kosmicznego w nowej erze, liczonej od 2020 roku.Although Vietnam has participated in numerous outer space operations with many nations worldwide, its legal system in this sector is still in its infancy and consequently has several restrictions. More specifically, this article investigates the establishment and evolution of policies, laws, and international cooperation regarding the utilization of outer space in Vietnam from 1979 to the present, with the turning point in 2006. The authors then give some predictions concerning the future pathway of Vietnamese space law in the new age from 2020

Depth Profiles of Microplastics in Sediment Cores from Two Mangrove Forests in Northern Vietnam

Plastics are essential materials that play critical roles in people’s lives in the modern world. However, plastic pollution in the ocean has become a critical environmental problem due to the fact of its durability and long life span. In the present study, we analyze the contamination of microplastics in sediment cores from mangrove forests of the Red River Delta and Tien Yen Bay in Northern Vietnam. The results showed that the concentration of microplastics in sediment cores ranged from 0 to 4941 particles/kg, with four types of microplastics: microfiber, microfragment, microfoam, and microfilm. Microplastics were not observed in sediment samples lower than 65 and 70 cm core depth in sediment cores from the Tien Yen Bay and Red River Delta. The microplastic concentration in sediment cores from the Red River Delta was significantly higher than those of Tien Yen Bay, reflecting the influence of anthropogenic activities on microplastics pollution. The present results highlight that the accumulation of microplastics may have occurred a long time ago and tends to increase in the future. Further investigation on microplastic accumulation rates, sources of microplastics, and reducing plastic pollution is necessary to minimize the impacts of microplastic pollution on aquatic life and the environment

Depth Profiles of Microplastics in Sediment Cores from Two Mangrove Forests in Northern Vietnam

Plastics are essential materials that play critical roles in people’s lives in the modern world. However, plastic pollution in the ocean has become a critical environmental problem due to the fact of its durability and long life span. In the present study, we analyze the contamination of microplastics in sediment cores from mangrove forests of the Red River Delta and Tien Yen Bay in Northern Vietnam. The results showed that the concentration of microplastics in sediment cores ranged from 0 to 4941 particles/kg, with four types of microplastics: microfiber, microfragment, microfoam, and microfilm. Microplastics were not observed in sediment samples lower than 65 and 70 cm core depth in sediment cores from the Tien Yen Bay and Red River Delta. The microplastic concentration in sediment cores from the Red River Delta was significantly higher than those of Tien Yen Bay, reflecting the influence of anthropogenic activities on microplastics pollution. The present results highlight that the accumulation of microplastics may have occurred a long time ago and tends to increase in the future. Further investigation on microplastic accumulation rates, sources of microplastics, and reducing plastic pollution is necessary to minimize the impacts of microplastic pollution on aquatic life and the environment

UNDERSTANDING FROM POLICY TO REALITY IN IMPLEMENTATION OF FOREST LAND ALLOCATION: INSIGHTS FROM TWO CASE STUDIES IN QUANG TRI PROVINCE, VIETNAM

Forest Land Allocation (FLA), initiated in 1992, aims to protect the forest and develop rural livelihoods. Although this policy has significantly contributed to the gaps between intentions and outcomes regarding forest and land policies in Vietnam, numerous problems and scepticism remain on the benefits for communities, especially ethnic minorities. Thus, this study aims to assess the implementation of FLA in the upland areas of Quang Tri province, thereby giving appropriate suggestions for the local government and indigenous people. With in-depth interviews and keynotes, a survey of 70 local people was carried out at Vinh O and Vinh Ha communes of Vinh Linh district in 2018. The results show that Vinh Ha commune has been implementing the policy since the beginning of 2018, with 5.2 ha of residential land allocated to 51 individuals/households; each received 0.1 ha on average. Meanwhile, Vinh O commune has completed the implementation of FLA to ethnic minorities since 2016. More specifically, 520.5 ha of land was allocated to 243 local people with an average of 2.14 ha/household. Of these, 55 households received 0.5–1.9 ha on average, and 188 households were allocated from 2 to 2.5 ha. Though both local authorities and communities have expressed great efforts, the implementation of land forest allocation policy in Vinh Linh district has been facing challenges because of limited human capacity, complex geography, biased economic policies, and overlap among organizations. They believe that flexibility should be accompanied by control and inspection by increasing stakeholder responsibility

Acetaminophen micropollutant: Historical and current occurrences, toxicity, removal strategies and transformation pathways in different environments

Acetaminophen (ACT) is commonly used as a counter painkiller and nowadays, it is increasingly present in the natural water environment. Although its concentrations are usually at the ppt to ppm levels, ACT can transform into various intermediates depending on the environmental conditions. Due to the complexity of the ACT degradation products and the intermediates, it poses a major challenge for monitoring, detection and to propose adequate treatment technologies. The main objectives of this review study were to assess (i) the occurrences and toxicities, (2) the removal technologies and (3) the transformation pathways and intermediates of ACT in four environmental compartments namely wastewater, surface water, ground water, and soil/sediments. Based on the review, it was observed that the ACT concentrations in wastewater can reach up to several hundreds of ppb. Amongst the different countries, China and the USA showed the highest ACT concentration in wastewater (≤300 μg/L), with a very high detection frequency (81–100%). Concerning surface water, the ACT concentrations were found to be at the ppt level. Some regions in France, Spain, Germany, Korea, USA, and UK comply with the recommended ACT concentration for drinking water (71 ng/L). Notably, ACT can transform and degrade into various metabolites such as aromatic derivatives or organic acids. Some of them (e.g., hydroquinone and benzoquinone) are toxic to human and other life forms. Thus, in water and wastewater treatment plants, tertiary treatment systems such as advanced oxidation, membrane separation, and hybrid processes should be used to remove the toxic metabolites of ACT

Novel Hybrid Swarm Optimized Multilayer Neural Network for Spatial Prediction of Flash Flood at Tropical Area Using Sentinel-1 SAR Imagery and Geospatial data

Flash floods are widely recognized as one of the most devastating natural hazards in the world, therefore prediction of flash flood-prone areas is crucial for public safety and emergency management. This research proposes a new methodology for spatial prediction of flash floods based on Sentinel-1 SAR imagery and a new hybrid machine learning technique. The SAR imagery is used to detect flash flood inundation areas, whereas the new machine learning technique, which is a hybrid of the firefly algorithm (FA), Levenberg–Marquardt (LM) backpropagation, and an artificial neural network (named as FA-LM-ANN), was used to construct the prediction model. The Bac Ha Bao Yen (BHBY) area in the northwestern region of Vietnam was used as a case study. Accordingly, a Geographical Information System (GIS) database was constructed using 12 input variables (elevation, slope, aspect, curvature, topographic wetness index, stream power index, toposhade, stream density, rainfall, normalized difference vegetation index, soil type, and lithology) and subsequently the output of flood inundation areas was mapped. Using the database and FA-LM-ANN, the flash flood model was trained and verified. The model performance was validated via various performance metrics including the classification accuracy rate, the area under the curve, precision, and recall. Then, the flash flood model that produced the highest performance was compared with benchmarks, indicating that the combination of FA and LM backpropagation is proven to be very effective and the proposed FA-LM-ANN is a new and useful tool for predicting flash flood susceptibilit