Van Thi Thanh Ho

The environmental pollution due to wastewater, especially domestic wastewater, is becoming more serious. Thus, this study was performed to assess the removal of pollutants by the combination of wetland technology, specifically constructed wetland (CW), with Para grass (Brachiaria mutica) together with the adsorption of red sludge. With an organic loading rate (OLR) of 120 (kg COD/ha/day), the treatment efficiency for wastewater in this study is quite high and the concentrations of parameters in the effluent were lower than the limits established by the QCVN 14:2015/BTNMT for domestic wastewater, which indicated the feasibility of this combination. These results are expected to open the possibilities of using environmentally friendly processes for wastewater treatment in urban and industrial areas.

Đánh giá thực trạng xử lý dầu vỏ hạt điều tại Việt Nam và đề xuất qui trình công nghệ tích hợp công nghệ IoT sản xuất dầu vỏ hạt điều tinh chế

Qualis indexed Engineering Journal and Science Journal to publish paper with DOI, NAAS Rating and journal has global recognized indexing

Direct methanol fuel cell (DMFC) attracts much attention due to its high abundance, environmental friendliness, and convenient transportation and storage. In this study, a novel catalyst of Pt₃Mo alloy nanoparticles (NPs) on non-carbon Ti_0.8W_0.2O₂ support was synthesized by microwave-assisted polyol process. The characteristic of Pt₃Mo NPS/Ti_0.8W_0.2O₂ catalyst was determined by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electronic microscopy (SEM), energy-dispersive X-ray (EDX), and Brunauer-Emmett-Teller (BET) method. Pt₃Mo NPs had an average diameter of approximate 5.18 nm and were uniformly anchored on Ti_0.8W_0.2O₂ surface. The ratio of Mo in the Pt₃Mo alloy was consistent with the theoretical value, which supported the effectiveness of the synthesis method. In addition, Pt₃Mo/Ti_0.8W_0.2O₂ electrocatalysts exhibited higher CO-like tolerance in methanol oxidation reaction (MOR) than commercial electrocatalysts, excellent catalytic activity, and strong durability after 2000 cycles. The synergistic effect of Pt-Mo alloy, and the strong interaction between the bimetallic Pt-Mo alloy and the mesoporous Ti_0.8W_0.2O₂ support, could weaken the Pt-CO bond. Besides, the high corrosion resistance and superior electrochemical durability of TiO₂-based oxide also contribute to the excellent stability of Pt₃Mo/Ti_0.8W_0.2O₂ electrocatalyst in harsh electrochemical media. These results revealed that this material could be a potential catalyst in DMFC technology.

The city Ho Chi Minh (HCMC) is one of the largest cities in Vietnam with the most dramatically economic development rate. Along with the economic development, the urbanization process in this city is also taking place very fastly. Due to the rapid urbanization and development, the emission rate from the industry and transportation leads to the increase in the amount of carbon dioxide (CO₂) which has been worsening the climate change. Protecting forests and conducting afforestation so that CO₂is transformed to nutrition through photosynthetic conversion is one of the most effective ways to mitigate the effects of climate change. As a result, the accumulation of CO₂emissions has become a global concern. Vegetation absorbs carbon dioxide, helps to conserve the environment, produces oxygen, reduces noise, and helps to stabilize subsurface water. This paper highlights the results of ENVI software which was used to interpret remote sensing images and Arcgis to evaluate the amount of carbon dioxide absorbed by vegetation in each administrative unit: district in HCMC and ward. According to the obtained results, the amount of CO₂absorbed in urban districts “District 1”, “District 3”, “District 4”, “District 5”, “Phu Nhuan District” is immensely low due to the high population density in the center of city. The population is mainly concentrated in the center districts but land area for vegetation is low. Regarding the suburban area, with mangrove forests, Can Gio District has the highest amount of CO₂absorbed of 35,894.075 tons/day and followed by Cu Chi District with 21,548.48 tons/day. It can be indicated that Can Gio and Cu Chi districts improtantly function like the greenhouse gas sinks for the whole HCMC. The success of this study could contribute to climate change mitigation and support in urban and land planning, as well as resettlement policies. Aside from that, CO₂emission and absorption assessment and evaluation in large–scale cities like HCMC has become a crucial, urgent, and practical issue nowadays.

Combining the current remote sensing platform combined and field survey is one of the effective methods to assess the impact of climate change on the distribution of plant cover as well as their structure. This study combined field surveys in April 2019 and image analysis from google earth pro in real-time in May 2006, 2009, 2013 to assess the change of Eleocharis group in Tram Chim national park. The results of the study showed that Eleocharis group, which admirably adapts to the acidic soil conditions (pH <4.5), had significant changes. Although water storage has created an extremely safe environment to avoid the impacts of wildfires, temperature rising at midday made Eleocharis less alive. It could be seen that climate change had affected the physiological characteristics of the tropical grass group, more specifically, made their ecological limits change and narrowed the distribution area of the most developed group in the national park.

Dragonflies are insects that have an association with wetland ecosystems and sensitive to changes in environmental factors. Therefore, under the increasingly strong impacts of climate change, they exhibit quite pronounced responses. Assessing the growth and development process of dragonflies can contribute positively to assessing and making strategies to cope with the impacts of climate change which is becoming increasingly complicated. The results of the current study showed that the Dragonfly species composition in Tram Chim National Park was remarkably diverse, including 11 species (2008) and 12 species (2019) of larvae belonging to 6 families in 2 subsets Zygoptera and Anisoptera. Based on information from field surveys, the results showed that the presence of dragonflies tended to be earlier than those recorded in the past, and it was often difficult to find them along the survey route, especially nearer to noon. Range, flight speed, and altitude were somewhat reduced, especially for Zygoptera. These environmental factors fluctuated greatly, which might cause pressing impacts on the growth and development of Dragonflies in the Tram Chim National Park area.

The issue of CO₂ emissions, the major caused leads to climate change has always been of particular interest in the context of the industrialization process and urbanization taking place more and more complex. Ho Chi Minh City is a large city of Vietnam with a high rate of urbanization and thus the CO₂ emissions management process needs to be studied. In this work, we have developed the Geographic Information System (GIS) to build the mapping of CO₂ emission from population of Metropolis, case study of Ho Chi Minh City in Vietnam for the first time. The mapping CO₂ emissions for Ho Chi Minh city from the population have been calculated from human respiration and combustion gas in daily activities. We found that the highest level of CO₂ emissions is located the western suburbs of the city including Binh Tan district, Tan Phu district, Tan Binh district, Go Vap district, District 12, Binh Chanh and Hoc Mon district. In seven districts with emission levels high, Binh Tan has the highest CO₂ emissions and opposite Can Gio district has the lowest CO₂ emission due to Can Gio district is a district adjacent to the sea and mainly mangroves forests, traffic condition is not conducive to the process of industrial development, therefore no attract workers from the others district, the province as Binh Tan district and local people trend to industrial zones making the district’s population the lowest. The results of this work can make reasonable policy in the management and reduction of CO₂ emissions for future cities with low carbon city.

Stabilization pond which is covered by aquatic plant is a environmentally friendly method to treat wastewater. In this study, stabilization pond using Para grass vegetation is applied to treat industrial wastewater and study the effect of intitial COD concentration and the N/P ratio on treatment abliity of para grass vegetation in the stabilization. The influent flow rate is controlled at 0.18 m3/h (corresponding to a retention time of 5.3 days). As inflow COD concentration is 203 ± 5.9 mg/L, COD treatment efficiency reaches 59.6 – 61.7%. When COD concentration in the input wastewater is 349.2 ± 4.5 mg/L, COD removal efficiency decreased to 55.7 0.9%. Continue to increase input COD concentration in the input to 512,6 ± 14,7 mg/l, COD treatment efficiency reduce to 47.9±0.6%. However, when increasing the input COD concentration corresponding to increasing the organic loading rate into the model, reached 10.270 kgCOD/ha.day at COD concentration = 512.6 ± 14,7 mg/L, twice higher than the organic loading rate of the model since COD concentration = 203 ± 5.9 mg/L. The result shows strong adaptability and wastewater treatment ability of facultative waste stabilization pond system covered by Para grass, although the input COD concentration or organic load increase more than doubled. The study also showed that the treatment efficiency of total nitrogen (TN) tends to increase when COD concentration in influent increases, with treatment effiency has reached from 57.2 to 76.4%. Besides, the fraction of nitrogen and phosphorus in influent also surveyed in this study. The fraction of N/P selected to survey in the study is approximately 2.26, 4.16 and 6.11. The results show that when increasing the N/P ratio, the efficiency of Total Nitrogen treatment tends to increase. At N/P ratio = 2.26 ± 0.19, even though the concentration of TN in the inlet is low, but nitrogen metabolism still takes place in the experimental model, so outlet TN concentration decrease to very low. The COD treatment efficiency increases gradually when increasing the N/P ratio. The output COD match Vietnam discharge standard QCVN 40:2011/BTNMT. These results show potential for applying the stabilization pond which is covered by Para grass for treating concentrated industrial wastewater.