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Intensive rice cultivation for a long time resulted in increasing soil degradation and less yield. This study aimed to evaluate effects of the combining reducing nitrogen fertilizer (N) with biochar amendment on soil chemical properties, rice growth parameters, and grain yield in the rice cultivation system in the Mekong Delta region, Vietnam (VMD). Field experiment was designed in the split-plot design with two factors, including N fertilizer (main plot) and biochar (sub-plot). Two N fertilizer rates were: (N50)—50 kg N ha–1 and (N100)—100 kg N ha–1, which is the farmer's practice. Biochar was amended with three rates: no applied biochar (B0), 5 t ha–1 (B5), and 10 t ha–1 (B10). The results indicated that reducing N fertilizer by 50% combined 5–10 t biochar ha–1 resulted in maintaining soil pH, soil electrical conductivity, soil organic carbon, cation exchange capacity, and rice biomass. Applying biochar at a rate of 5–10 t ha–1 significantly increased the available N, available P, and rice height compared to the treatment with no applied biochar (B0). Rice yield in the treatments applied with 5–10 t ha–1 was significantly higher than the treatment without the use of biochar by 11.6–14.7%. The findings of this study confirmed that reducing 50% N fertilizer combined with 5 t ha–1 or 10 t ha–1 of biochar could improve soil available N, available P, rice growth, and grain yield in intensive rice cultivation systems in the VMD region. [ABSTRACT FROM AUTHOR]

Heavy metal contamination in agricultural land is an alarming issue in Vietnam. It is necessary to develop suitable remediation methods for environmental and farming purposes. The present study investigated the effectiveness of using peanut shell-derived biochar to remediate the two heavy metals Zn and Pb in laboratory soil assays following Tessier's sequential extraction procedure. The concentration of heavy metals was analyzed using Inductively coupled plasma mass spectrometry (ICP-MS). This study also compared the effectiveness of the blend of biochar and apatite applied and the mere biochar amendment on the chemical fractions of Pb and Zn in the contaminated agricultural soil. Results have shown that the investigated soil was extremely polluted by Pb (3047.8 mg kg−1) and Zn (2034.3 mg kg−1). In addition, the pH, organic carbon, and electrical conductivity values of amended soil samples increased with the increase in the amendment's ratios. The distribution of heavy metals in soil samples was in the descending order of carbonate fraction (F2) > residue fraction (F5) > exchangeable fraction (F1) > Fe/Mn oxide fraction (F3) > organic fraction (F4) for Pb and F5   ≈   F2 > F1 > F3 > F4 for Zn. The peanut shell-derived biochar produced at 400 °C and 600 °C amended at a 10% ratio (PB4:10 and PB6:10) could significantly reduce the exchangeable fraction Zn from 424.82 mg kg−1 to 277.69 mg kg−1 and 302.89 mg kg−1, respectively, and Pb from 495.77 mg kg−1 to 234.55 mg kg−1 and 275.15 mg kg−1, respectively, and immobilize them in soil. Amending the biochar and apatite combination increased the soil pH, then produced a highly negative charge on the soil surface and facilitated Pb and Zn adsorption. This study shows that the amendment of biochar and biochar blended with apatite could stabilize Pb and Zn fractions, indicating the potential of these amendments to remediate Pb and Zn in contaminated soil. [ABSTRACT FROM AUTHOR]

Given that rice husk biochar has been shown to modulate salinity in salt-affected acid soils, the objective of this study was to investigate the effects of organic amendment of salinized acid soils on P fractions, enzyme activities, and associated rice yield. Four treatments, viz. Rice–Rice–Rice, [RRR]; Fallow–Rice–Rice, [FRR]; Fallow–Rice–Rice + 3 Mg ha−1 of compost [FRR + Comp]; and Fallow–Rice–Rice + 10 Mg ha−1 of biochar [FRR + BC] were established at Ben Tre and Kien Giang sites, Viet Nam, over six consecutive crops. Soil properties at harvest of the sixth crop showed that there were diverse patterns of fractionation between P forms with respect to treatment. Overarchingly, biochar increased labile and moderately labile inorganic P and organic P by 30% to 70%, respectively, whilst compost had a relatively modest effect on these pools. Soil phosphatase activities at crop tillering increased following the FRR + Comp and FRR + BC treatments compared with those in RRR, except for acid phosphatase at Ben Tre. At harvest, there were no significant differences between the enzyme activities among the treatments. Rice yield was positively correlated with the more labile forms of P, soil C, and acid phosphatase activity. In the absence of organic amendments, there was no effect of triple versus double rice crops being grown in one-year cycle. Repeated application of biochar (10 Mg ha−1 × 5 times) showed potential to increase grain yields and total soil C in salt-affected acid soils, via modulation of P transformations to more plant-available forms. [ABSTRACT FROM AUTHOR]

This study aimed to optimize the recovery of ammonium and phosphate from wastewater using Mg-modified biochar as an adsorbent. Given the situation of domestic wastewater and agricultural waste in Vietnam, the researchers fabricated biochar from rice husk and modified it with magnesium salt to make it an effective material for wastewater treatment. To determine the optimal conditions for the experiments, the response surface methodology was used, specifically the central composite design (CCD) model with four factors, namely biochar dosage (g/L), pH, N:P ratio, and initial concentrations of NH4+ and PO43- . The material was thoroughly characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) to ensure that it met the desired specifications. Based on the experimental design, the optimal conditions were determined to be a biochar dosage of 0.12 g/L, an N:P ratio of 1.25, an initial concentration of 60 mg/L, and a pH of 6. Tests conducted in synthetic wastewater produced results that were in agreement with the predicted values. However, when the optimized values were tested in domestic wastewater, only phosphate removal showed good agreement with an efficiency of 93% compared to the predicted optimization value of 88%. This study demonstrates the potential of Mg-modified biochar as an effective adsorbent for recovering ammonium and phosphate from wastewater. Although further optimization may be required for ammonium removal in domestic wastewater, the results are promising and warrant further investigation. [ABSTRACT FROM AUTHOR]

This study estimated the climate change effects of alternative rice production systems in North Vietnam with different residue management options, using Life Cycle Assessment (LCA). The traditional practice of open burning of residues (System A) was compared with the alternative of converting residues to biochar, which was returned to the same land area from which the residues were obtained (System B). Pyrolytic cook-stoves and drum ovens were assumed to be used by households to produce biochar, and the cook-stoves produced heat energy for cooking. The annual rate of biochar applied was determined by the amount of biochar produced from the straw and husk available. We assumed that agronomic effects of biochar increased with each annual biochar application until reaching maximum benefits at 18 Mg ha −1 , which takes eight years to be produced in pyrolytic cook-stoves and drum ovens. The largest contributor to the carbon footprint of rice at the mill gate, was CH 4 emissions from soil, in both systems. Biochar addition reduced the carbon footprint of spring rice and summer rice by 26% and 14% respectively, compared with System A, in the first year of application. These values substantially increased to 49% and 38% after eight years of biochar addition. The climate effect of System B was most sensitive to the assumed suppression of soil CH 4 emissions due to biochar application. [ABSTRACT FROM AUTHOR]

In this study, porous biochar (PBC) was prepared by acid activation of biochar derived from food waste (FWBC) and used as a suitable approach for the removal of 4-chlorophenol (CP) in wastewater. The characterization of PBC and the influent of different experimental conditions are determined. After the acid activation process, the surface area, porosity, and functional groups of PBC were developed. The removal performances of CP (1 mg/L) by PBC and FWBC were archived at 97.8 and 82.1%, respectively. Adsorption kinetics and isotherms of CP were followed by the second-order and Langmuir models, respectively. The maximum capacities of CP uptake onto mono-layer of FWBC and PBC based on the Langmuir model were determined at 79.8 and 108.7 mg/g, respectively. Besides, PBC could remove more than 89% CP from wastewater within 45 min of reaction time and it is suitable to reuse 8 times with over 60% adsorption efficiency of CP. In addition, the adsorption mechanism and environmental impact were discussed in detail. This work could bring a sustainable approach to the treatment of CP in wastewater as well as the management of food waste in Vietnam. [ABSTRACT FROM AUTHOR]

In this work, alginate-modified biochar derived from rice husk waste was synthesized using a simple process. The modified biochar (MBC) and rice husk biochar (RhBC) were investigated for removing Pb (II) ions in wastewater. The BET result displayed significantly improved specific surface area of MBC up to 120 m2/g along with a total pore volume of 0.653 cm3/g. FTIR spectrums presented the higher oxygen-contained functional groups of MBC as compared to RhBC, resulting in increasing adsorption capacity of Pb (II). MBC had higher adsorption capacity (112.3 mg/g) and faster removal rate (0.0081 g mg−1 min−1) than those of RhBC (41.2 mg/g and 0.00025 g mg−1 min−1). Modified RhBC can remove more than 99% of Pb (II) from wastewater and it could be utilized for three cycles with a removal performance of over 90%. In addition, the Pb adsorption mechanism by using MBC was proposed and the practical application of MBC for the treatment of wastewater in Vietnam was discussed. [Display omitted] • Alginate modified rice husk biochar (MBC) was used for Pb (II) removal in wastewater. • MBC had higher adsorption capacity (112.3 mg/g) as compared to others adsorbents. • More than 99% of Pb (II) in wastewater sample was removed by MBC. • MBC still has high efficiency of Pb (over 90%) after 3 times reused. [ABSTRACT FROM AUTHOR]

Background: Economic benefit has been analyzed for the yield of farming products when designing a farming system, while waste treatment also generates profitable energy products for this system. The economic factor is decisive in decision-making for applying waste treatment solutions for a small-scale farming system. A household farming system in the Mekong Delta generates many kinds of organic wastes, but most of the agricultural waste resources are disposed of into the environment. Methods: This study approaches an analysis of economic–environmental–energy (EEE) efficiency for waste treatment of an integrated livestock-orchard (LO) system on a household scale in the Mekong Delta. This novel analysis method is based on the energy content of biomass and its cost. The EEE efficiency is optimized to gain objective functions regarding energy yield efficiency, system profit, and CO2 sequestration for the treatment model. The algorithms are built for optimizing these objective functions. Results: The optimization results show the treatment model of pyrolysis and pelleting gain all the objective functions with high efficiency. The model is efficiently applied for the LO system that generates more than 100 kg of orchard residues and 3000 kg of pig manure. The system with a charcoal oven and pellet machine is capable to gain energy efficiency due to its potential biofuel products, such as biochars and pellet products. A treatment model of composting, pyrolysis, and pelleting gives the best performance of overall EEE efficiency. Conclusions: This work has proven economic benefits from integrating biogas tank, charcoal oven, and pellet machine in an integrated LO system. The system contributes not only for reducing CO2 emissions but also for supplementing secondary renewable bioenergy, as well as for increasing incomes and thus supporting livelihoods for the local farming households. [ABSTRACT FROM AUTHOR]

Despite being a promising biomass source for gasification, the practical use of rice straw in Vietnam is hindered by its low gasification efficiency. This study introduces an innovative approach by integrating the production of syngas and CO 2 adsorbent during the gasification process of rice straw, departing from the conventional focus solely on improving gasification efficiency. Results showed that the gasification of rice straw, conducted in the 20 kWe commercial gasification system (PP20 All Power Lab), attained a thermal conversion efficiency of 58.7%. Syngas produced exhibited consistent composition, with CO and H 2 content ranging from 12.1% to 15%, CO ranging from 16.9% to 22.1%, and CH 4 ranging from 1.9% to 3.9% throughout the operation, demonstrating relative stability. Notably, a considerable amount of residual char, accounting for 22.1 wt% of the initial feedstock, was generated. Characterized by notable traits such as high surface basicity, aromaticity, and a dense concentration of (ultra-)micropores, the residual char demonstrates suitability for applications in CO 2 adsorption. In controlled laboratory conditions (25 °C, 1 atm, without heat-mass transfer limitations), the adsorption capacity reached 1.2 mmol g−1. Transitioning to more practical conditions (40 °C, 1 atm, within a 2-cm adsorbent bed subject to diffusion constraints), the CO 2 adsorption capacity of the residual char ranged between 2% and 4.8% of the adsorbent's weight, while the CO 2 /N 2 selectivity measured between 25.5 and 29.7. These findings underscore the significant potential of integrating syngas and CO 2 adsorbent production through rice straw gasification, indicating a promising avenue for sustainable energy and carbon capture technologies. [Display omitted] • Stable syngas quality obtained throughout rice straw gasificatiom. • Use of residual char after gasification as cost-effective and scalable CO 2 adsorbents. • CO 2 capture capacities reached up to 1.2 mmol g−1 at 25 °C, 1 atm. • Potential for cascading use of rice straw for energy and adsorbent production. [ABSTRACT FROM AUTHOR]

Durian is one of the most valuable and expensive fruits in Vietnam and Southeast Asia. Leaf nutritional disorders are considered to be causes of reductions in fruit yield and quality. However, studies on the nutritional balance in durian leaf are limited. In this study, we used the DRIS method for leaf limitation nutrient diagnosis at the stage 2 months before durian flowering. Our objectives were to (i) establish DRIS norms for the macronutrients (N, P, K, Ca, Mg, and S) in durian leaf and (ii) determine nutrient value ranges that are insufficient or excessive in durian production. A total of 180 leaf samples were collected and examined from 90 durian orchards cultivated on alluvial soils in the Vietnamese Mekong Delta. The results indicate that DRIS establishment for durian was highly reliable due to the significant positive correlation (r > 0.5) among nutrient indices. The limiting nutrients in durian leaf at the investigation stage were S, Mg, Ca, and P, where S and Mg were the most deficient. The optimal ranges of nutrients in durian leaf were determined and recommended in this study. Further studies are necessary to validate the efficiency of DRIS using nutrient omission trials under durian cultivation. [ABSTRACT FROM AUTHOR]

Vietnam's Mekong Delta region contains a sizable amount of acid-sulfate soil, which has properties that harm plants, such as low pH, aluminum and iron toxicity, hydrogen sulfide and sulfate acid. The study aims to gather helpful information about the problems with acid sulfate soils' chemical makeup so that suggestions can be made for improving these soils in the Mekong Delta. These methods mainly review studies and projects on the properties, constraints and management improvement of acid-sulfate soils and recommend the proper methods for sustainable use. The Mekong Delta contains many sulfidic or acid-sulfate-producing materials. Soils that contain acid sulfate are especially vulnerable to the consequences of climate change. Therefore, evaluating and predicting how acidic soil impacts soil quality and the affected factors such as drought, water scarcity, rainstorms, floods and saltwater intrusion are essential. Selecting cultivars that can withstand acid sulfate or salt is easy and inexpensive. Designing appropriate farming models is necessary in the interim. To correctly manage and exploit acid sulfate soils in the current situation, one must also be aware of their distribution, physicochemical makeup and biological properties. [ABSTRACT FROM AUTHOR]

Vietnam heavily relies on pork as its primary source of animal protein. Traditional farming methods, characterized by small-scale operations, dominate the industry. However, challenges such as rising feed costs, disease outbreaks, and market volatility are prompting many farmers to abandon their businesses. Recognizing the pivotal role of the swine sector in both economic development and nutrition, authorities must intervene to prevent its collapse. In developed nations, smart pig farming, utilizing technologies like sensors and cameras for data collection and real-time decision-making, has significantly improved health and productivity. These technologies can detect subtle indicators of animal well-being, enabling prompt intervention. This review aims to analyze the drivers of Vietnam's swine farming, identify existing production system flaws, and explore innovative precision farming methods worldwide. Embracing precision farming promises to enhance Vietnam's competitiveness in export markets and bolster consumer confidence. However, reliance solely on expensive foreign technologies may benefit large-scale farms, leaving smaller ones behind. Therefore, fostering local innovation and validating cost-effective solutions will be crucial for the sustainable growth of small- and medium-scale pig farming in Vietnam. [ABSTRACT FROM AUTHOR]

Landfills have the potential to contribute to mercury (Hg) pollution, due to the burial of waste containing mercury. Mercury from domestic waste can enter the soil surrounding landfills through surface runoff and leachate. In this study, we assessed the levels of Hg in the paddy soil around the Nam Son landfill, the largest landfill in the North of Vietnam, during both rainy (September 2021) and dry (January 2022) seasons. The concentration of Hg was in the range of 20.5 to 79.7 μg/kg dry w.t. in Bac Son and Nam Son, and 16.6 μg/kg dry w.t. at a higher reference site. In most of the samples, the rainy season showed higher Hg concentrations than the dry season. Soil samples taken closer to the landfill exhibited higher levels of Hg contamination compared to those in more distant paddy areas, suggesting a decreasing trend of Hg concentration as one moves away from the pollution source. Additionally, Hg concentration was found to decrease vertically from the surface, with the higher value observed in the surface layer (0–5 cm), and the lower in the bottom layer (20–25 cm). The geo-accumulation index showed that all the sampling points were moderately to heavily polluted, indicating that Hg was lost from the waste source in the landfill. This study provides valuable insights into the spatial and vertical distribution of Hg pollution in the topsoil and highlights the importance of managing and assessing the risks of Hg-containing waste. [ABSTRACT FROM AUTHOR]

Sustainable development is a subject of study and consideration by scientists and policymakers, especially the sustainable development of the night-time economy. The night-time economy refers to the various economic activities and businesses that primarily operate during the evening and night hours, typically from 6 p.m. until early morning. It includes a diverse range of sectors such as entertainment, dining, hospitality, and nightlife, with establishments such as bars, clubs, restaurants, theaters, and live music venues playing a significant role. The development of the night-time economy refers to the process of managing and promoting the growth of economic activities during the evening and night hours in a manner that balances economic, social, and environmental considerations. Therefore, the paper aimed to identify the factors affecting the night-time economy in Hanoi to achieve the sustainable development of this economy. The paper processed and analyzed the data using SPSS Statistics 26.0 software. The quantitative study included (1) testing the suitability of the scale for the variables using Cronbach's alpha, (2) analyzing the EFA factors to check the convergence of the observed variables and the separation between the independent variables, (3) checking the correlation to evaluate the problem of multicollinearity of the model, and (4) performing regression analysis to evaluate the impact of the factors on night-time economic development in Hanoi City. The empirical results showed that the variables positively impacted night-time economic development in Hanoi. However, the study found differences in the levels of their impact. Among the four factors, factor 3 (promotion and sharing) had the strongest impact on night-time economic development, followed by factor 2 (city infrastructure and safety), factor 1 (institutions and environment), and factor 4 (nature and resources). The empirical results will help policymakers promote the sustained development of the night-time economy in Hanoi, Vietnam. [ABSTRACT FROM AUTHOR]

Water sources for irrigation systems in the Red River Delta are crucial to the socioeconomic growth of the region's communities. Human activities (discharge) have polluted the water source in recent years, and the water source from upstream is limited. Currently, the surface water quality index (WQI), which is calculated from numerous surface water quality parameters (physical, chemical, microbiological, heavy metals, etc.) is frequently used to evaluate the surface water quality of irrigation systems. However, the calculation of the WQI from water quality monitoring parameters remains constrained due to the need for a large number of monitoring parameters and the relative complexity of the calculation. To better serve the assessment of surface water quality in the study area, it is crucial and essential to conduct research to identify an efficient and accurate method of calculating the WQI. This study used machine learning and deep learning algorithms to calculate the WQI with minimal input data (water quality parameters) to reduce the cost of monitoring surface water quality. The study used the Bayes method (BMA) to select important parameters (BOD5, NH4+, PO43−, turbidity, TSS, coliform, and DO). The results indicate that the machine learning model is more effective than the deep learning model, with the gradient boosting model having the most accurate prediction results because it has the highest coefficient of determination R2 (0.96). This is a solid scientific basis and an important result for the application of machine learning and deep learning algorithms to calculate WQI for the research area. The study also demonstrated the potential of artificial intelligence algorithms to improve water quality forecasting compared to traditional methods with minimal cost and time. [ABSTRACT FROM AUTHOR]

The discharge of untreated oily wastewater into the environment has serious impacts on human health, living nature, and ecosystems and leads to significant economic losses. Many engineering techniques have been proposed and applied to treat oily wastewater, but limited studies have investigated low-cost and effective techniques using by-products and waste/scrap materials from the construction industry. Materials to treat oily wastewater are needed not only to mitigate environmental pollution but also to promote the reuse and recycling of industrial by-products, especially in developing countries. This study, therefore, examined the sorption capacity of dispersed oil in wastewater (dispersed soybean oil in water; initial oil concentrations, Ci = 10–1000 mg/L; oil droplet size in water <2 μm) onto the hydrophobized/oleophilized autoclaved porous aerated concrete (AAC) grains made from waste scrap in Vietnam by using batch sorption tests in the laboratory. The AAC grains (sizes 0.106–0.25, 0.25–0.85, and 0.85–2.00 mm) were hydrophobized/oleophilized using oleic and stearic acids (coating concentrations of 1.0, 5.0, and 10 g/kg), and two sands (0.18–2.00 and 0.30–2.00 mm) were used as control samples. The results showed that the hydrophobized/oleophilized AAC grains had high sorption capacity for dispersed oil (i.e., high oil removal efficiency) compared to the control sands. Especially, the removal of AAC grains coated with stearic acid was >80% in high oil concentration solutions (Ci = 100 and 1000 mg/L), indicating that the hydrophobized/oleophilized AAC grains have high potential as useful adsorbents to trap dispersed oil in oily wastewater. Moreover, adsorption isotherms were drawn to examine the sorption characteristics of dispersed oil onto AAC grains. For all tested samples, the sorption of dispersed oil increased linearly with increasing equilibrium concentration. The commonly used Langmuir model, on the other hand, did not capture the measured isotherms. [ABSTRACT FROM AUTHOR]

The prevalence of microplastics (MPs) in the environment has had a significant impact on ecosystems and posed a major threat to human health. This study investigated the distribution and characteristics of MPs in the Nhue - Day River basin in Vietnam, which is a critical source of biodiversity and used to support the economic growth of about 12 million people. The effect of seasonal variation and anthropogenic activities on the MP abundance was assessed. The findings revealed that the MPs abundance was significant in this study area. The average abundance of MPs in the dry season (754 items/m³) was insignificantly higher than that in the rainy season (706 items/m³) with n=9. The range in the abundance of MPs in the dry and rainy seasons was 49-2,827 and 400-1,133 items/m³, respectively. Microplastics in fiber forms were dominant in both seasons. The majority of the collected MPs were in the 0.5-2.0 mm size range, varying from 71% to 100% of the total MPs depend on sampling point. The total percentage of MPs size 0.3-0.5 mm in the dry season was 56.97% compared to 119.85% in the rainy season, indicating that the MPs were broken into smaller pieces due to UV exposure and weather conditions. Colored items occupied the majority of the MPs. This study can be used to gain a better knowledge of MP pollution in Vietnam's river water. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the process of waste treatment (wastewater and solid waste) within an intensive catfish farming agro-based zero emission integrated system (AZEIS) in which the fish farming, livestock and cultivation are combined in the same area , as well as the role of this process for soil cultivation of the garden in the same integrated system. The material flow analysis (MFA) technique was used throughout the study for calculating efficiency of waste treatment processes and also for conversion/accumulation of materials with purpose to improve the soil quality for cultivation purpose in the garden. The experimental results showed that the garden in the system plays an important role in receiving, conversion, uptake and accumulation of the nutrients from waste flows, and by that way, in effective removal the pollutants from waste flows as well. In this system, the wastewater from catfish ponds was treated by using water morning glory, a local aquatic plant, before to be reused for watering the cultivation plants in the garden, and the removal percentage of Total Organic Carbon, Nitrogen, Phosphorus and Kallium in wastewater were 33.3, 21.7, 59,5 and 37,5%, respectively. All the solid wastes (sludge from catfish ponds, cow manure from livestock, and absorbed biochar material) were reused as organic fertilizer (compost), and served as sources of additional nutrients for cultivation of Pennisennon purpurecums-schumach grass and maize plants in the garden. Biochar material, which was produced from dried leaves in the garden, was used for treatment of biogas effluent before using later for watering the garden. Total wastewater after being treated and reused for maize plants was 9575 m3/ha, in which absorbed water by maize plant was 48.02 m3/ha, and 9527 m3/ha was evaporated and accumulated in soil. The Nitrogen absorbed by maize plant was 4.12 g/m2, and the soil organic carbon stock in the AZEIS system was 0.19 mg/ha/crop. • The garden in the agro-based zero emission integrated system (AZEIS) of an intensive catfish farming plays an important role conversion and accumulation of the nutrients, and in waste treatment as well. • The wastewater was treated by using Spinach water morning glory, a local aquatic plant; all organic solid wastes were reused for producing organic fertilizers for cultivation of Pennisennon purpurecums-schumach grass and maize; biochar material was used for treatment of wastewater. • The organic sources and macronutrients (N, P and K) has helped to improve physico-chemical property of cultivation soil, and to enrich the nutrients for the soil, reduce the use of chemical fertilizer etc. [ABSTRACT FROM AUTHOR]

The owners of SMEs in Vietnam mainly focus on business performance in the short term. In recent years, FDI firms have demonstrated interest in both business efficiency and sustainable development. These issues have attracted the attention of scientists and policy makers in Vietnam. Therefore, this study aimed to determine the factors affecting the performance of small and medium enterprises in Vietnam regarding the Sustainable Development Goals (SDGs). Using the latest published survey data up to March 2022 for food and beverage, wood and steel foreign direct investment enterprises, combined with a data envelope analysis model in step one and Tobit regression in step two, the results from this quantitative study are as follows: (1) the production efficiency index of Vietnamese FDI enterprises ranges from 82.5% to 89% depending on the industry (assuming variable output to scale); (2) the factors financial leverage, renewable consumption, scale and operating time are related to the performance of FDI enterprises, and have a positive effect on performance; and (3) financial leverage and renewable consumption can generally boost a firm's performance in the case of FDI SMEs in the food and beverage, wood and steel industries. This research also suggests some solutions to achieve the Sustainable Development Goads (SDGs) in the FDI SMEs of Vietnam. [ABSTRACT FROM AUTHOR]

This study proposes an integrated cattle breeding and cultivation system that provides zero emission and sustainable livelihood for the community in rural areas. The proposed integrated farming system improves agricultural productivity and environmental and sanitation conditions, minimizes the amount of waste, and increases the family income up to 41.55%. Several waste types can be recycled and transformed into valuable products, such as energy for cooking, organic fertilizer for crops, and cattle feed for breeding. Wastewater effluent from the biogas tank can be treated by biochar and results show that it then meets the standards for irrigation purposes. Also, the waste flow from cattle breeding supplies enough nutrients to cultivate plants, and the plants grown supply are adequate food for the 30 cows living on the farm. This research shows that the use of an integrated farming system could achieve zero-emission goal. Thereby, it provides a sustainable livelihood for cattle breeding family farms. The proposed integrated cattle breeding and cultivation system improves agricultural productivity, environmental and increases the farmer income up to 41.55%. Image 1 • Cattle breeding integrated system forwards zero emission in rural areas. • Washing waste water from cattle shed produce biogas to support for household cooking. • Cattle shed produce compost and vermicomposting to support for gardens. • Crop wastes from garden are collected and made biochar to treat biogas effluent. • Organic materials from biogas effluent absorbed by biochar's reuse for composting process. [ABSTRACT FROM AUTHOR]

Background: Both exergy and energy analysis methodologies are used for analysing energy efficiencies in various processes, including agriculture. This study focuses on the connection of three main process components (husbandry-crop-fishpond) in a typical farming household located within an acid soil region of rural Vietnam. The concept of exergy analysis is used to underline the potential for resource efficiency in alternative processes in the agricultural system. For development of an integrated ecological system aiming towards zero emissions, the analytical methods of material cycles and energy flows utilized a set of indicators of resource efficiency in a sustainable agriculture. Results: The design of the ideal integrated farming system "Agro-Industrial Zero Emissions Systems" (AIZES) can increase the system efficiency by making use of indigenous natural materials and waste reuse/recycling. Recycling waste produce energy, fish feed and fertilizer can result in a decreased environmental load of approximately half. Using exergy analysis to calculate an indicator non-renewable yield ratio (NRYR), the systems verified sustainability of agriculture production. Conclusions: The farming household will be able to subsidize their fuel and electricity consumption by utilizing biogas. Surplus biogas will be distributed to proximate households, further creating sustainable goals. Biochar, created by mixing the biomass residues with local plants, will improve soil quality and pig sludge, mixed with biomass residue, will create high-quality fertilizer. [ABSTRACT FROM AUTHOR]

Shade trees may have contrastive effects on Robusta coffee (Coffea canephora Pierre ex A. Froehner) yield, which may be additionally influenced by soil properties and reproductive stages of the plant. The current study is aimed at examining the interaction effects of shade trees, soils with different properties, and reproductive stages on coffee yield and identifying key factors influencing the yield. The current study was conducted in Dakha, Kontum of Vietnam on 133 farms, randomly selected from two soils, and two reproductive stages of coffee plants planted with and without shade trees. The coffee yield was measured, and surface soil samples were taken from these farms to be analyzed for 16 variables. The results showed that shade trees enhanced coffee yield significantly (by 28%) in the young reproductive stage but exhibited an insignificant effect in the old stage. The silt fraction, total nitrogen, cation exchange capacity, and shade trees were key factors determining 52% of the coffee yield in the sandy clay loam soil, while silt content and shade trees determined 23% of the yield in the clay soil. These findings suggest that shade trees, together with some soil properties, should be considered to improve coffee production under a tropical monsoon climate region. [ABSTRACT FROM AUTHOR]

Agricultural production is one of the main sources of anthropogenic greenhouse gas (GHG) emissions, contributing 50% and 60% of CH4 and N2O emissions, respectively. This study evaluated the rice yield and components, the CH4 and N2O emissions and the global warming potential between the triple rice (R-R-R) and sesame-rice rotation (S-R-R) systems in Can Tho city, Vietnam. The experiments were conducted in three cropping seasons: spring-summer 2016, summer-autumn 2016, and winter-spring 2016–2017. The results showed that there was no significant difference in the yield components and grain yield between the triple rice and sesame-rice rotation systems. The application of a sesame rotation in rice-based system could reduce the CH4 and N2O emission by 30.5% and 18.7%, respectively. The global warming potential in the S-R-R rotation was 9 860 kg CO2e/ha, significantly lower than the R-R-R rotation (12 410 kg CO2e/ha) by 20.6%. These results show that the S-R-R rotation has the potential to mitigate the GHG emissions, especially CH4, which contributes a large amount of emissions in the rice cultivation. [ABSTRACT FROM AUTHOR]

ZSM-5 zeolite was successfully synthesized from bentonite clay sourced from Lam Dong Province, Vietnam, using the hydrothermal method at 170 °C for 18 h. The synthesized ZSM-5 (SiO 2 /Al 2 O 3 ratio ~ 34) exhibited a single phase with high crystallinity (91.8%), and a clear and uniform shape. In a detailed examination of the synthesized material's Pb(II) adsorptive capacity, various factors were taken into account, including pH, interaction time, ionic strength, and the amount of adsorbent. Isotherms and kinetics were examined to elucidate the uptake behavior. Study results suggested that Pb(II) ion uptake by ZSM-5 was most appropriately described by the Sips isotherm and intraparticle diffusion kinetic models. The calculated maximum monolayer adsorption capacity according to the Langmuir isotherm model was 48.36 mg/g. Furthermore, the adsorption mechanisms of Pb(II) on ZSM-5 involving electrostatic interactions, ion exchange, and diffusion into pores were demonstrated using the analytical techniques before and after Pb(II) adsorption. These findings demonstrate that ZSM-5 synthesized from bentonite clay exhibits an excellent adsorption capacity for Pb(II), resulting in promising applications for treating drinking water or aqueous industrial waste containing Pb(II) ions., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Rainwater harvesting (RWH) systems can be used to produce drinking water in rural communities, particularly in developing countries that lack a clean drinking water supply. Most previous research has focused on the application of RWH systems for individual urban households. This paper develops a yield-after-spillage water balance model (WBM) which can calculate the reliability, annual drinking water production (ADWP) and benefit–cost ratio (BCR) of a community-scale RWH system for rural drinking water supply. We consider multiple scenarios regarding community aspects, including 150–1000 users, 70–4800 kL rainwater storage, 20–50 L/capita/day (LCD) drinking water usage levels, local rainfall regimes and economic parameters of Australia (developed country) and Vietnam (developing country). The WBM analysis shows a strong correlation between water demand and water supply with 90% system reliability, which allows both Australian and Vietnamese systems to achieve the similar capability of ADWP and economic values of the produced drinking water. However, the cost of the Vietnamese system is higher due to the requirement of larger rainwater storage due to larger household size and lower rainfall in the dry season, which reduces the BCR compared to the Australian systems. It is found that the RWH systems can be feasibly implemented at the water price of 0.01 AUD/L for all the Vietnamese scenarios and for some Australian scenarios with drinking water demand over 6 kL/day. [ABSTRACT FROM AUTHOR]

For effective management of water quantity and quality, it is absolutely essential to estimate the pollution level of the existing surface water. This case study aims to evaluate the performance of twelve machine learning (ML) models, including five boosting-based algorithms (adaptive boosting, gradient boosting, histogram-based gradient boosting, light gradient boosting, and extreme gradient boosting), three decision tree-based algorithms (decision tree, extra trees, and random forest), and four ANN-based algorithms (multilayer perceptron, radial basis function, deep feed-forward neural network, and convolutional neural network), in estimating the surface water quality of the La Buong River in Vietnam. Water quality data at four monitoring stations alongside the La Buong River for the period 2010–2017 were utilized to calculate the water quality index (WQI). Prediction performance of the ML models was evaluated by using two efficiency statistics (i.e., R2 and RMSE). The results indicated that all twelve ML models have good performance in predicting the WQI but that extreme gradient boosting (XGBoost) has the best performance with the highest accuracy (R2 = 0.989 and RMSE = 0.107). The findings strengthen the argument that ML models, especially XGBoost, may be employed for WQI prediction with a high level of accuracy, which will further improve water quality management. [ABSTRACT FROM AUTHOR]

This study aimed to (i) select endophytic bacteria in maize root for its phosphorus solubilization ability and (ii) evaluate the efficacy of selected indigenous bacterial strains on soil fertility, phosphorus (P) uptake, growth, and maize yield. A total of 31 maize root samples were collected from An Phu District, An Giang Province, to isolate the bacteria. In addition, the pot experiment was conducted with nine treatments of (i) 100% P of the recommended fertilizer formula (RFF), (ii) 75% P of the RFF, (iii) 50% P of the RFF, (iv) 25% P of the RFF, (v) 75% P of the RFF plus a mixture of the 3 selected strains, (vi) 50% P of the RFF plus a mixture of the 3 selected strains, (vii) 25% P of the RFF plus a mixture of the 3 selected strains, (viii) 0% P of the RFF plus a mixture of the 3 selected strains, and (ix) 0% P of the RFF plus none of the 3 selected strains. The results identified 72 isolates from LGI medium. All isolates were screened in a broth medium at pH 5.0, but only 16 isolates obtained OD660 > 0.5. All 16 isolates were able to solubilize various insoluble P fractions. Of those, strain ASD-21 had the highest P solubilization ability for the insoluble Al-P compound. Strains ASD-08 and ASD-21 had the highest Fe-P concentration at 39.8-41.5 mg P L-1. Strains ASD-08 and ASD-21 had the highest Ca-P concentration (46.6-51.3 mg P L-1) for 48 h of incubation. They were identified as Enterobacter spp. Results also showed the application of a mixture of strains ASD-08, ASD-10, and ASD-21 increased soil fertility by increasing phosphorus content by 13.7 mg P kg-1 and replacing 25% of P fertilizer, but this mixture did not change maize yield. [ABSTRACT FROM AUTHOR]

Assessment of ecosystem services is vital for successful natural resource allocation; however, these have been less studied within Vietnam. This study estimated the ecosystem services value (ESV) and its change in Cham Chu nature reserve, Vietnam using a benefit transfer method. Ecosystem service values estimation and trend analyses were carried out based on land use and land cover datasets from 1986, 1998, 2007, and 2017, with their corresponding global value coefficients. The results revealed that the total value of ecosystem services in Cham Chu was approximately 64.4, 63.9, 60.7, and 63.4 million USD in 1986, 1998, 2007, and 2017, respectively. Changes have also occurred in the values of individual ecosystem service functions. From 1986 to 2017, ecosystem service functions showed significant decreases in gas regulation, pollination, biological control, water regulation, water supply, and food production of 62.9%, 51.2%, 44.4%, 24.7%, 23.1%, and 13.0%, respectively. We conclude that the loss of ESV is a result of ecological deterioration in the studied landscape, and we propose further research to examine future solutions and establish action strategies. In summary, the research approach methodology developed can be used by land managers and planners in Vietnam as a guideline to estimate the importance of ecosystem services in Vietnam. [ABSTRACT FROM AUTHOR]

Ehretia asperula (E asperula) is a well-known traditional medicinal plant in Vietnam with potent activity against a wide range of diseases, including hepatitis B and various cancers. Although E asperula has been used in traditional medicine, the efficacy of E asperula and its bioactive components on retinal degenerative diseases has not been fully evaluated. In present this study, we found that ethanolic extracts of E asperula increased cell viability in retinal precursor cells exposed to glutamate/BSO-induced excitotoxicity/oxidative stress. The major responsible bioactive compounds were rosmarinic acid and methylrosmarinic acid. First, 10 known compounds were isolated from E asperula leaves. Their chemical structures were determined using 1D and 2D nuclear magnetic resonance, and compared with published data. Using high-performance liquid chromatography, we determined the content of 4 compounds in E asperula extract: rosmarinic acid, lithospermic acid B, astragalin, and kaempferol 3-rutinoside. The most abundant of these com)pounds was lithospermic acid B. The protective effects of the pure compounds and ethanolic extracts against excitotoxicity and oxi)dative stress-induced retinal cell death were tested in R28 cells. Both 70% and 95% ethanolic extracts of E asperula increased cell viability in these conditions. Rosmarinic acid and methyl rosmarinic acid were more effective at protecting against retinal cell death and elevated reactive oxygen species in cells subjected to glutamate/BSO-induced excitotoxicity/oxidative stress. These find)ings suggested that E asperula could potentially be used to treat retinal degeneration. [ABSTRACT FROM AUTHOR]

The Vietnam's agricultural sector had to challenge with its course and learned lessons of further development. Novel policy might be adopted to encourage the private investments and sectors in agriculture. Furthermore, an introduction of new models such as climate-smart or green agriculture and application of modern technology increased productivity at the same time and creating jobs for millions of agricultural workers and reversing the massive rural-urban migration flux. Vietnam's agricultural sector needs to maintain the reform momentum, particularly liberalization policy, and to boost up agricultural potential. Obstacles such as land limitation policy must be removed to enable large-scale production and encourage private investment in the agricultural sector. To avoid being trapped by its own success, Vietnam is now shifting the old development paradigm that focuses too much on the quantity to the quality of the agricultural production. The government makes major efforts to achieve at the same time agricultural growth, better livelihood of the farmer, and the development of the rural areas. However, Vietnam still needs to prepare a "transition strategy" to overcome the impact of the technological progress on the traditional agricultural workers. [ABSTRACT FROM AUTHOR]

Spent coffee ground (SCG) is a residue released during coffee brewing. Disposal of SCG is able to lead to a loss of bioactive constituents and have a negative impact upon the environment. This study aimed to explore fatty acids, bioactive phenolics, antioxidant and anti-aging potentials of SCG samples obtained from coffee shops in Ho Chi Minh city, Vietnam. The oil content of the SCG samples ranged from 6.3 to 10.5%, and linoleic (43%), palmitic (33.4%) and oleic (11%) acids were identified as major constituents of the oil. Chlorogenic acid was the most abundant phenolic acid examined (832.9–7657.7 μg/g of dry weight), followed by ferulic acid (40.5–1041.7 μg/g). Through anti-collagenase and anti-elastase assays, SCG showed a promising anti-aging activity, with IC50 values comparable with those of epigallocatechin gallate. The correlation analysis revealed gallic acid positively correlated with the free radical scavenging potential evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl) assay and the inhibitory effect on elastase. The results demonstrated that utilization of SCG prepared from Vietnamese coffee could open new avenues for food and cosmeceutical industry. [ABSTRACT FROM AUTHOR]

In this paper, the chromium, Cr (VI), ion adsorption ability of oyster shell samples collected from two sea regions in Vietnam (Phu Yen province and Quang Ninh province) was investigated and compared. The oyster shell samples were calcined at different temperatures and denatured by using ethylenediaminetetraacetic acid (EDTA). The Cr (VI) ion adsorption ability of the prismatic (PP) and nacreous (NP) shell layers of oysters was also evaluated. The characteristics of oyster shell samples before and after treatment were determined by using analysis methods including XRD, IR, BET, UV-Vis, and FESEM. The Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich models and fit statistic equations were used to study the adsorption isotherms of Cr (VI) ion adsorption by oyster shells. The Cr (VI) ions adsorption kinetic has been set up using four reaction models consisting of first-order, pseudo-first-order, second-order, and pseudo-second-order reaction models. Effects of experimental factors on the Cr (VI) ion adsorption process using oyster shells were also investigated and discussed in this work. [ABSTRACT FROM AUTHOR]

Small-scale household digesters have been promoted across Asia as a sustainable way of handling manure. The major advantages are that they produce biogas and reduce odor. However their disadvantages include the low recycling of nutrients, because digestate is dilute and therefore difficult to transport, and the loss of biogas as a result of cracks and the intentional release of excess biogas. In this study, life cycle assessment (LCA) methodology was used to assess the environmental impacts associated with biogas digesters in Vietnam. Handling 1,000 kg of liquid manure and 100 kg of solid manure in a system with a biogas digester reduced the impact potential from 4.4 kg carbon dioxide (CO2) equivalents to 3.2 kg CO2 equivalents compared with traditional manure management. However, this advantage could easily be compromised if digester construction is considered in the LCA or in situations where there is an excess of biogas which is intentionally released. A sensitivity analysis showed that biogas digesters could be a means of reducing global warming if methane emissions can be kept low. In terms of eutrophication, farms with biogas digesters had 3 to 4 times greater impacts. In order to make biogas digesters sustainable, methods for recycling digestates are urgently require [ABSTRACT FROM AUTHOR]

CO2 emissions reduction from coal-fired power plants is an urgent issue in Japan, as well as around the world. The purpose of this study is to estimate the CO2 emissions and economy of using carbonized wood pellets produced overseas and co-fired at coal-fired power plants in Japan. We examined carbonized wood pellets produced in Canada and Vietnam, since those countries are major exporters of wood pellets for Japan. The results obtained are as follows: (1) The CO2 emissions and calculated cost per calorific value of carbonized wood pellets (CP25), which have a fixed carbon content of 25 wt.%, are lower than those of wood pellets at the port of import in Japan. When the fixed carbon of carbonized biomass is controlled at 25 wt.% or more via a carbonizer, sufficient pyrolysis gas (the heat source used for drying and carbonization without auxiliary fuel) can be obtained. (2) Carbonized wood pellets manufactured in Vietnam are more economical than those manufactured in Canada, since the resource of wood is less expensive and the transportation distance is shorter from Vietnam compared to Canada. (3) When carbonized wood pellets at CP25 are co-fired in coal-fired power plants, they do not affect the cost of the electricity generated, even if the carbonized pellets are blended at a high ratio. [ABSTRACT FROM AUTHOR]

Avoidance of intensive rice cultivation (IRC) and soil amendments are potential practices to enhance soil properties. There is only limited information on the effects of reduced IRC and its mixture with compost or silicate fertilizer (Si) on the soil nematode community in salt–affected soils. This study aimed to assess the shifts of soil nematode community by reducing a rice crop from triple rice system (RRR) to a double rice system and mixed with compost or Si in paddy fields in acid sulfate soil (ASS) and alluvial soil (AL) in the Mekong Delta, Vietnam. Field experiments were designed with four treatments in four replicates, including RRR and a proposed system of double–rice followed by a fallow (FRR) and with 3 Mg ha–1 crop−1 compost or 100 kg ha–1 crop−1 Si. Soils were collected at harvest after the 2 year experiment, reflecting the fifth and third consecutive rice crop in RRR and FRR system, respectively. Results showed that reduced IRC gave a significant reduction in abundance of plant–parasitic nematodes (PPN), dominated by Hirschmanniella and increased abundance bacterivorous nematodes when mixed to compost and silicate fertilizer in ASS. In addition, reduced IRC increased nematode biodiversity Hill's indices and reduced herbivorous footprint in ASS. Proposed system having compost or Si had strongly increased in bacterivorous and omnivorous footprints. Particularly, reduced IRC mixture with Si increased abundance of Rhabdolaimus, Mesodorylaimus and Aquatides, metabolic footprints (structure footprint, bacterivorous, omnivorous and predator) and diversity Hill's N1 index in ASS. Our results highlighted that reduced IRC was a beneficial practice for decreasing abundance of PPN in salt-affected soils and increasing abundance of FLN in ASS. IRC mixture with compost or Si had potential in structuring the nematode communities with increasing biodiversity, trophic structure, and metabolic footprints. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the soil contamination and the accumulation of arsenic (As) and heavy metals including chromium (Cr), copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) in 15 native and cultivated plant species in a Pb recycling area of Dong Mai village, Hung Yen Province, Vietnam. The analysis of 32 soil samples collected from seven different sites in the study area revealed that the contents of Al, Fe, As, Cr, Cu, Zn, Cd, and Pb in the soils ranged from 6200–32,600, 11,300–55,500, 5.4–26.8, 24.9–290, 66.0–252, 143–455, 0.71–1.67, and 370–47,400 mg/kg, respectively. The contents of As, Cr, Cu, Zn, Cd, and Pb in rice grains and the shoots of 15 plant species ranged from 0.14–10.2, 1.00–10.2, 5.19–23.8, 34.7–165, 0.06–0.99, and 2.83–1160 mg/kg-dry weight (DW), respectively. Hymenachne acutigluma (Steud.) Gilliland, a potential hyperaccumulator of Pb (1160 mg/kg-DW), is considered the best candidate for phytoremediation of Pb-contaminated soil. The cultivation of rice and vegetables, and the use of some native plants for food for humans, pigs, and cattle should be managed with consideration of the accumulation of Pb in their aboveground biomass. [ABSTRACT FROM AUTHOR]