Science & Technology Development Journal: Science of the Earth & Environment

Long-term trend analysis of climate factors and their impacts on flows in some river basins in Viet Nam

Hien Trong Dieu Le — 2024-06-30

Basins in Vietnam recently, have experienced the changes in climate that could have impacts on water resources in these basins. Therefore, it is important to study long-term trends in water flows as well as their influencing factors, such as temperature and precipitation. This study focuses on analyzing long-term trends of water flows in three basins of Vietnam including: Dong Nai, Ca, and Hon -Thai Binh rivers. Water flows data from 44 hydrological stations provided by the national hydro-meteorological forecasting center were analyzed using the Mann-Kendall test and Sen’slope. Additionally, climate data were analyzed for the period 1990–2019. Trend analysis was performed on water flow data at monthly, seasonal, and yearly scales. Overall temperatures and precipitation across the basins have increased since 1990, whereas stream-flows have tended to decrease across the three basins. However, this trend pattern may not be consistent across all monitoring stations within each basin.

Implementation of material flow cost accounting (MFCA) to improve waste recovery efficiency for pig farming

Nam Thi Phuong Ngo — 2024-06-30

The aim of this study is to analyze and evaluate the circularity of material flows according to the material cost flow accounting (MFCA) approach for an integrated ecological model for small-scale pig farming. MFCA is considered a typical tool for environmental management accounting. The calculation is carried out on an integrated ecological model in An Dinh commune, Mo Cay Nam district, Ben Tre province, with two main initial processes: pig farming and coconut cultivation, and additional connected sub-systems to close the circular ecological loop, including biogas, vermicomposting and biochar systems. Applying material flow analysis, the inflow and outflow of processes are costed. Costs are divided into three groups: material costs, energy costs, and system costs. MFCA calculation results show that, when applying the integrated ecological model, the percentage of lost costs is only 7.87%, compared to 14.08% when not applying the integrated model. The only lost part is dead pigs, which need to be handled and cannot be utilized in any form. Other wastes from one process are turned into resources for another process, bringing dual economic and environmental benefits. Flowing material costs in the research framework clearly demonstrate the benefits of applying Integral Ecology, promoting widespread application by farmers in agricultural production, and implementing green agriculture and circular economies.

Characteristics of microplastics in Surface Sediments from the Coastal Area of Binh Thuan Province

Huyen Pham Thu — 2024-06-30

Today, environmental pollution, particularly microplastic pollution, is emerging as a significant environmental concern. With their small size and high durability, microplastics have a long-term impact on the environment and human health. In this study, microplastics in deep-sea sediments of Binh Thuan province were identified using Fourier-transform infrared spectroscopy (µ-FTIR) performed on the Nicolet iN10 MX infrared microscope. The results revealed a microplastic density ranging from 740 to 1593.6 MPs/kg in dry sediments. Microplastic shapes, including fragments, fibers, and nurdles (balls), were prevalent, with fragments dominating at 65.52%. The majority of microplastic particles fell within the size range of 50 to 150 μm, constituting 44.1% of the total. Diverse polymer types of microplastics were determined, including (PET (Polyethylene Teraphalate), Vinyl ester, MUF (Melamine-urea-formaldehyde resin), EVOH EVAL film, Fluoropolymer, HDPE (High-density Polyethylene), MF (Melamine-formaldehyde cond), LDPE (Low density polyethylene), PE (Polyethylene), CP (Cellophane), Nylon, and five other types, with a 31.72% prominent prevalence of PET in the sediment samples. The findings of this research demonstrated the presence of microplastics and the diversity of their polymer types, contributing to the assessment of microplastic accumulation in sediments and the potential environmental pollution, which could impact ecosystems, organisms, and human health.

Improving nitrogen recycling in an aquaponics system by adding a composting process from fish sludge

Tran Trung Kien — 2024-06-30

The goal of this research is to recover nutrients from wastewater sludge and recirculate them as organic fertilizer in aquaponics systems. Improving the sustainability of aquaponics by increasing economic and environmental efficiency. In this study, an improved aquaponics system was developed including a fish pond, biological reactor, growing bed, and composting site. In addition, an ecological floating bed is placed on the surface of the fish pond to absorb nutrients in the fish pond. After a farming cycle lasting more than 3 months, the biomass of Cyperus haspan is harvested and mixed with fish sludge from the biological reactor tank to produce organic fertilizer. The nitrogen and carbon balance model was established to evaluate the nutrient recovery efficiency of the aquaponics system. The results indicate that nutrient recovery from fish sludge can also address the problem of nutrient deficiency faced by aquaponics systems and reduce the costs associated with the purchase of additional nutrients. Besides, 32 - 45% of N originating from fish feed is assimilated into plant biomass. It is estimated that about 35-45% of unaccounted N is lost to the atmosphere, the remaining 20-25% into wastewater, and 0.8-3% into solid waste. The average weight of fish harvested in the system is 531±94.2 g/fish with a survival rate of 80%. Plant biomass in three harvests reached 1.8 to 2 kg/m2.

Applying life cycle assessment (LCA) and life cycle costing (LCC) tools for waste recovery model in super-intensive shrimp farming system in Ca Mau province

Thắng Việt Nguyễn — 2024-06-30

This study aims to evaluate the environmental sustainability and economic efficiency of waste recovery solutions from a typical super-intensive shrimp farming household (shrimp farming on tarpaulin ponds) in Ca Mau province based on on the life cycle assessment (LCA) tool that focuses on assessing greenhouse gas emissions combined with life cycle cost (LCC) for post-recovery products. Options considered to treat wastewater and sludge towards zero emissions from shrimp farming households include: i) wastewater treatment using a system of settling ponds and biological treatment ponds; ii) sludge treatment with biogas tank and composting. The results show that greenhouse gas emissions are mostly in the operating phase (electricity consumed by operating the circulating water pump from the second biological pond to the household's current farming system), accounting for 29.5% compared to other periods. The proposed system of circulating wastewater and sludge solutions for super-intensive shrimp farming shows economic benefits when for every 1m3 of water reused, people benefit 32.22 VND and 1kg of Compost people benefit. benefited 786.67 VND. The limitation of the study is that it has not calculated the amount of greenhouse gases generated from the respiration of animals and aquatic plants participating in the wastewater treatment process in biological treatment ponds. Finally, the CO2 emissions of the auxiliary facilities are calculated for the first farming crop. When the model operates stably for the following years, CO2 emissions will be significantly reduced due to no new construction.

Applying the Geographic information system (GIS) to create an vadose zone map of the Pleistocene aquifer in the coastal area of Ba Ria-Vung Tau province

Au Hai Nguyen — 2024-06-30

The vadose zone is an important component in assessing the ability of the aquifer to be affected by surface contaminants, serving to assess the vulnerability of the aquifer. This study has initially applied spatial calculation and interpolation tools in a geographic information system (GIS) environment to create thematic maps to help visualize contamination assessment from surface activities, especially in areas with many groundwater exploitation activities through Pleistocene aquifer characteristics data in the coastal area of Ba Ria-Vung Tau (BR-VT) province. The vadose zone in the study area is relatively uniform in thickness, with 87.2% of the aquifer area ranging from 10 to 23 meters, distributed mainly in the West - Southwest of the area. The vadose zone with a thickness of over 23 m only account for 9.73% of the study area, mainly in the Southeast of the area (Dat Do district). At the same time, the silt and clay composition of 92.16% of the Pleistocene aquifer vadose zone is relatively thin, consisting primarily of sand and gravel. The vadose zone has less silt and clay in central area of Phu My town. Only 7.84% of the aquifer area has thick silt and clay components appearing in the vadose zone of the coastal areas of Dat Do district and Vung Tau city. The results show that the Pleistocene auifer distributed in the hinterland and almost the entire Xuyen Moc district is more sensitive to pollutants, susceptible to direct penetration by surface activities due to less protection from the silt and clay in the vadose zone.

Emission inventory and simulation of air pollution for developing an air quality management plan for Tra Vinh Province (Vietnam) period 2022-2025

Lê Việt Thắng — 2024-06-30

Tra Vinh is a coastal province in the Mekong Delta region. In recent years, increasing economic and social development activities have been creating great pressure on the air environment in the province. Therefore, it is very necessary to develop a provincial air quality management plan to provide solutions to manage and control air pollution in the province. The study conducted an emissions inventory from three main sources (mobile, point and area sources) by using the emission factor method. Emission inventory results show that point source emission is dominated by NO2 (64.4%) and SO2 (92.7%). Meanwhile, the main pollutant of traffic source is CO (69.0%) and area source are TSP, PM10 and PM2.5 (59.1%, 72.5% and 71.1% respectively). Emission inventory data is used as input data for air quality simulation study (FVM-TAPOM model) according to the current scenario in 2022. In addition, the study also builds scenarios pollution emissions based on Tra Vinh's socio-economic development planning to 2025. The simulation results show that the air quality in Tra Vinh province is still good, the simulated parameters values lower than the threshold according to QCVN 05:2023/BTNMT. On that basis, the study has developed solutions to control air environment quality in the coming time, contributing to sustainable development for the locality and the Mekong Delta region.

Statistical Effect Of Activation Condition for Heterogeneous Fenton Catalyst Derived From Jackfruit Peel Waste on Pentachlorophenol Removal in Water

Dai Hue Ngan — 2024-06-30

Application of heterogeneous Fenton catalyst based activated carbon derived from biomass for persistent organic pollutant’s removal in wastewater has been considered a promising treatment approach toward circular economy and environmental protection. However, statistical evaluation on preparation conditions for a catalyst derived from jackfruit peel applied for Pentachlorophenol (PCP) degradation in water has not been investigated yet. This study investigated statistically single and the combined effect of temperature and ratio between iron and activated carbon produced from jackfruit peel (Fe/JAC) on capability of PCP degradation in water. Physio-chemical characteristics of Fe/JAC catalyst including surface morphology, crystal structure, element contribution and surface functional groups were analyzed with methods of Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDS) and Fourier Transform Infrared Spectroscopy (FTIR), respectively. The results revealed that synergetic and quadratic effects of temperature and Fe/JAC ratio were statistical contributors on the PCP degradation in water. The results of the quadratic model indicated effective degradation of PCP in water when temperature and Fe/JAC ratio were from 298℃ to 500 and 12.4 to 20.0%, respectively. The Fenton catalytic properties for PCP decomposition in the best conditions of 20%Fe/JAC at 500℃ has large pores with the active sites of Fe₂O₃ with size ranged from 500 to 700 nm and oxygen functional groups.