We proposed an innovative hybrid intelligent approach, namely, the multiboost based naïve bayes trees (MBNBT) method for the spatial prediction of landslides in the Mu Cang Chai District of Yen Bai Province, Vietnam. The MBNBT, which is an ensemble of the multiboost (MB) and naïve bayes trees (NBT) base classifier, has rarely been applied for landslide susceptibility mapping around the world. For the modeling, we selected 248 landslide locations in the hilly terrain of the study area. Fifteen landslide conditioning factors were selected for the construction of the database based on the one-R attribute evaluation (ORAE) technique. Model validation was done using statistical metrics, namely, sensitivity, specificity, accuracy, mean absolute error (MAE), root mean square error (RMSE), and the area under the receiver operating characteristics curve (AUC). Performance of the hybrid model was evaluated and compared with popular soft computing benchmark models, namely, multiple perceptron neural network (MLPN), Support Vector Machines (SVM), and single NBT. Results indicated that the proposed MBNBT (AUC = 0.824) model outperformed the popular models, namely, the MLPN (AUC = 0.804), SVM (AUC = 0.804), and NBT (AUC = 0.800) models. Analysis of the model results also suggested that the MB meta classifier ensemble model could enhance the prediction power of the NBT model. Therefore, the MBNBT is a suitable method for the assessment of landslide susceptibility in landslide prone areas.

Saltwater intrusion, a consequence of climate change and decreased water levels, has been increasingly severe in the Mekong Delta region. Thanh Phu District, Ben Tre Province, Vietnam, is a coastal region where agricultural production and local livelihood have been impaired by saltwater intrusion, resulting in the adoption of multiple coping strategies, including rotations and intercropping. This study aims to measure and evaluate soil and water quality indicators of multiple farming systems in Thanh Phu district and contributes to developing suitable cropping patterns. Soil indicators were pH, electrical conductivity, and exchangeable Na⁺. Water quality characteristics include pH, salinity, dissolved N and P, alkalinity, H₂S, and chemical oxygen demand (COD). The results indicated that water pH and salinity were at suitable levels to support the growth of prawn but were below the critical level required to grow black tiger shrimp and white-legged shrimp. Water alkalinity, dissolved N, P, and COD were not constraining for the growth of shrimps. However, a significant concentration of H₂S may cause disadvantages for shrimp growth.

Hospital wastewater contains pharmaceutical residues, chemicals, and pathogens that cause coloration and nourish pathogenic microorganisms. The objective of the study was to evaluate the effectiveness of a medical wastewater treatment system at Military Hospital 175 (Ho Chi Minh City, Vietnam) that combined a membrane bioreactor (MBR) system with nanofiltration (NF). The influent of the system was the wastewater discharged from the operating rooms of the hospital. The system has a capacity of 50 L/day and operates at three organic load rates (OLR) of 0.5, 1.5 and 2.5 kgCOD/m³day (COD: Chemical oxygen demand), in which each load rate operates for 40 days. The results showed that most nutritional criteria generally achieved positive results. Specifically, the average COD removal was shown to be consistently high throughout the three phases at 94%, 93.3%, and 92.7%, respectively. For removal of nitrogen, the system demonstrated efficiencies of 75%, 79%, and 83%, respectively, to three phases. The log removal value (LRV) for Escherichia coli and coliform bacteria were higher than four throughout the study period. The average removal efficiency for color and total iron was approximately 98% and 99%, respectively. The water quality after treatment, especially after NF, meets the Vietnamese standard of grade A. The arrangement in which the MBR preceded NF was also found to limit the amount of soil and solids entering subsequent treatment, which therefore improved the efficiency of NF, as demonstrated by the stability of post-NF transmembrane pressures throughout three cycles renewed by two backwashes.

Silver nanoparticles (AgNPs) find a wide range of use in many fields, and the biosynthesis of AgNPs via biological routines has recently gained currency. In this study, Bacillus licheniformis TT01 strain was isolated from quail feces collected in Vietnam and evaluated for its ability to synthesize AgNPs. Through visual confirmation and ultraviolet and visible (UV–Vis) spectrum analysis, we found that the biosynthesis of AgNPs was realized in the process in which biomass of B. licheniformis TT01 was incubated with AgNO₃ solution. Obtained AgNPs were then assayed for antibacterial activity against three species of bacteria, namely Escherichia coli, Bacillus cereus and Ralstoniasolanacearum, showing better inhibitory action than the AgNO₃ solution and the bacterial extracellular fluid. The minimum inhibitory concentration (MIC) of AgNP solution was 206 ppm against E. coli and R. solanacearum and 343.3 against B. cereus. X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed that the obtained AgNPs had a spherical shape and sizes ranging from 2 to 22 nm, in which particles from 2 to 10 nm appeared with the highest frequency.

The effects of ultrasonic and ozonation pretreatments on organic solubilization, anaerobic biodegradability, and biogas production were elucidated in this study. Two pretreatment methods for batch anaerobic digestion for biogas recovery with the same material and experimental conditions were the focus for comparison. Anaerobic digestion experiments were conducted at ambient temperature with the solid retention time set to 25 days. The obtained results indicated that the soluble chemical oxygen demand increased from 0.344 without pretreatment to 1.023 and 1.228 g/L with ultrasound and ozone pretreatments, respectively, whereas the yields of biogas production in the 25 days increased by 32.3 and 52.9% via ultrasonic irradiation and ozonation relative to the control case, respectively. The biodegradability of the organic compounds of the samples for the cases of ultrasound, ozone pretreatments, and control achieved 55.9, 64.31, and 39.18%, respectively, in terms of chemical oxygen demand (COD) removal efficiencies. The physicochemical characteristics of sludge flocs were investigated via scanning with particle sizes, which were obviously affected by pretreatments of sonication and ozonation, resulting in finer particles than in the control case.