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

Occurrence analysis and scenario development for domestic solid waste management in Vung Tau City

Song Toan Pham Phu — 2023-11-12

Domestic solid waste management (DSWM) in Vung Tau City (VTC) is emerging as an envi-ronmental problem behind rapid urban development. The amount of DSW increased rapidly, leading to a disturbance in the collection, transportation, and challenges in the implementation of DSWM at the source. This study aims to assess the situation and develop and analyze the scenarios of the DSWM system for VTC, thereby proposing strategies to improve the DSWM system for the city in 2024 - 2033. The scenarios of the DSWM system were built based on the situation analysis, the national and regional SWM regulations, and scientific assumptions that have been studied in Viet Nam. This study showed that the amount of DSW in VTC has in-creased rapidly at the rate of 7,4%/year over the past decade and reached 457.9 tons in 2022. About 80% of the DSW is collected by 500 informal collectors, who work spontaneously and are unmanaged. The minimalist and optimal DSWM models have been built and evaluated. The results showed that these two models of the DSWM should be applied in two phases, 2024-2028 and 2029-2033, respectively. According to this roadmap, the amount of DSW to the land-fill was estimated to reduce 26% of the total waste generation. The amount of recovered recy-clable waste is also estimated to be increased five times compared to 2023. Furthermore, the quality of DSW in the treatment area is suitable for composting and handling by waste-to-energy solutions.

Research on evaluating the efficiency of recovery nutrients (N, P) in an integrated ecology system for catfish farming

Tran Trung Kien — 2023-12-31

The purpose of this is to evaluate the ability to recover nutrients (N, P) emitted from catfish farming by using an integrated ecological system towards zero emissions. An integrated system has been designed and implemented for a catfish pond with a water surface area of 10,300 m2. Wastewater is treated with water hyacinth, sludge is used for organic fertilizer production, and dead fish carcasses are used as raw material for liquid fertilizer production. The SFA (substance flow analysis) method was applied to evaluate the efficiency of nutrient source recovery in the system. The results show that the nutrient supply to fish ponds is mainly from fish food (about 30,450 kgN/ha/crop and 3,675 kgP/ha/crop). Harvested fish in the adult stage accumulate N and P content in fish biomass of 12,480 kgN ha/crop and 540 kgP/ha/crop respectively. Wastewater from fish ponds sent through aquatic ditches has an amount of 11,509 kgN/ha/crop and 2,978 kgP/ha/crop. The treatment efficiency of the aquatic pond reached 70%, and the amount of nutrients emitted into the environment through wastewater was 3,453 kgN/ha/crop and 893 kgP/ha/crop respectively. The efficiency of retaining nutrients after composting is about 70 - 80%, the product of this process is organic fertilizer containing N and P contents of 0.26% and 0.12% respectively.

Assessment of water quality in Hau river flowing through Vinh Long province using principal component analysis

Anh Thi Lan Nguyen — 2023-12-31

Water is one of the most important and precious resources for the human life and species, a particularly important factor to ensure the successful implementation of strategies and plans for economic and social development, and to ensure national security. However, water quality is significantly degraded by global climate change and increasing over-exploitation activities. The study assessed the water quality on the Hau River, the part running through Vinh Long province, as an information sourse for the water resources management and protection in this river. Water quality data used in the study provided by the Department of Natural Resources of Vinh Long province at 7 sites on the Hau river. The results show that at most of the monitoring locations, temperature and pH were consistent with the lifespan of aquatic organisms. TSS parameters, and the content of nutrients and organic matter exceeded national water surface standards. Applying principal component analysis (PCA), we investigated the relationship between water quality parameters. The results of PCA analysis showed that COD, BOD5, pH, Coliform, P-PO43-, N-NO3-, TSS, and EC have the key factor on the quality in Hau river flowing through Vinh Long province mainly originating from areas of aquaculture, agricultural and industrial activities. Therefore, it is necessary to include these 8 criteria as the key criteria in the surface water quality monitoring and surveying program of the Hau river flowing through Vinh Long province.

Removal of doxycycline antibiotics in water with adsorbents derived from banana peels

Thi Dieu Hien Vo — 2023-12-31

This study evaluated the antibiotic removal efficiency of doxycycline (DOX) of biochar prepared from banana peels with different temperatures. Factors affecting antibiotic adsorption (including pH, initial DOX concentration, contact time, biochar dose) were studied. The results show that biochar generated at high temperature (800 oC) and modified by KOH (BP-KOH), has higher antibiotic adsorption capacity than those at low temperature (no pyrolysis and 500 oC pyrolysis, BP and BP500 respectively). The properties of the materials were determined by the scanning electron microscope (SEM), Fourier Transform Infrared Spectroscopy (FITR), zeta potential, and Brunauer–Emmett–Teller (BET) analysis methods. The SEM image shows that the fabricated material contains many pores. FTIR spectra show that the fabricated material contains surface functional groups such as O - H, C - H, C - C, etc. The BET results show that high surface area of BP-KOH (710.214 m2/g). The DOX adsorption capacity (120 mg/L) of BP-KOH obtained a high treatment efficiency of 97.9% with an adsorption time of 1440 minutes (24 h) with an optimal pH of 6. Research results showed found that adsorbent made from banana peel has great potential in the application of antibiotic treatment in water.

The effect of agricultural waste inhibit the uptake of Cadmium (Cd) by pak choi in assumption conditions of contaminated soil

Luong Thi Thu Trang — 2023-12-31

This study aimed to explore the effects of agricultural waste (rice straw-RS and maize stalks-MS) in reducing Cd toxicity. Experiments in the study determined: growth of pak choi, total Cd concentration in the plant and the change in distribution of Cd fraction in the soil. Results showed that: agricultural waste application may detoxify Cd at excessive concentrations (3 and 6 mg/kg) by transforming mobile Cd fractions (EXC-Cd and CAB-Cd) into semi-mobile and non-mobile Cd fractions (FEM-Cd, OM-Cd, and RES-Cd); the Cd concentrations in pak choi decreased and pak choi growth increased. However, a significant reduction in Cd concentration can only occur when agricultural waste application is at an appropriate content (20 g/kg). In addition, agricultural waste application promoted the growth of pak choi at lower content (10 g/kg). Furthermore, this study also showed a good correlation between the ratio of mobile Cd fractions (EXC-Cd and CAB-Cd) with Cd concentration in pak choi and plant growth. This study suggested that agricultural waste application, especially rice straw, plays an important role in preventing Cd uptake by plant tissues at excessive concentrations through transformations into immobile Cd fractions.

Distribution of microplastics in surface water from Saigon River to Can Gio Sea

Nguyen Thao Nguyen — 2023-12-31

In recent years, microplastic pollution has emerged as a critical issue that has far-reaching impacts on the environment, organisms, and humans alike. As a result, there has been a growing need for in-depth studies aimed at analyzing and understanding the abundance, physical, and chemical characteristics of microplastics in different environments. This study, conducted in June 2021, sought to do that by examining the prevalence of microplastics in surface water samples from the Saigon River and Can Gio Sea, and comparing their distribution from the river to the sea. The study involved the collection of thirty surface water samples from both the Saigon River and Can Gio Sea, which were subsequently analyzed through the extraction of microplastics from the water samples and identification using infrared spectroscopy. The results of the study showed that microplastics were present in all surface water samples, with an average abundance of 0.80 ± 0.58 pieces/m3 in the Saigon River and 0.24 ± 0.45 pieces/m3 in the Can Gio Sea. These findings highlight the severity of the problem, which affects both freshwater and marine ecosystems. It is noteworthy that microplastics with sizes larger than 1 mm and fragment shape were found to dominate in both sampling areas. Additionally, the study revealed that many colors were found, with white and transparent colors accounting for over 50% of the total microplastic abundance. Comparing the results of this study with the 2020 study conducted by the same research group, it was evident that lightweight plastics such as polyethylene, polypropylene, and ethylene-vinyl acetate continued to play an important role in microplastic pollution in this area. In light of these findings, it is clear that plastic pollution is a pressing issue that demands immediate attention and action. The impact of microplastics on the environment, organisms, and human health is undeniable, and as such, there is an urgent need to develop strategies aimed at reducing their impact.

Studying environment characteristics of cultivation land in Dai Thinh Area, Me Linh District, Ha Noi city to serve sustainable development of health safe vegetables

Vinh Thi Dang — 2023-12-31

Cultivation land (Planting Soil) is a natural resource that plays an important role for organisms and humans. Soil pollution will badly affect human and animal health through food, vegetables, fruits, medicinal herbs, etc. To clarify the characteristics of the geochemical environment and estimate the quality of the soil environment in the Dai Thinh area, Me Linh district, Hanoi city, the authors combined the using of traditional and modern methods in the research process, such as: field research methods, grain-size analytical method plus X-ray fluorescence spectroscopy (XRF) method to determine the major components (oxides) of soil. The high-frequency inductive plasma source spectroscopy combined mass spectrometry (ICP-MS) method and optical AAS atomic adsorption spectroscopy have been used to determine the concentration of critical heavy metals in soil samples. Besides, the direct measurement method used to determine environmental indicators (pH, Eh, Ec). Research results show that agricultural soil in the studied area belongs to the group of heavy sandy loam, sandy loam, and sandy clay soils, with average content of sand (size of 0.05-2mm): 60.8 (%), silt (limon) (size of 0.005-0.05mm): 17.96 (%), clay (size of <0.005mm): 21.46 (%). The soil has not been yet polluted by critical heavy metals such as: As, Cd, Cu, Zn, Cr, Ba, Sb, Co, Mo, Se and Sn. The soil in the studied area shows neutral acid-base values (average pH is 6.61), has a strong oxidizing environment (Eh > 150mV) (with values of Eh ranging from 183 to 310 mV), and is not saline (values of Ec ranging from 58.7 - 317.0 (µS/cm). Therefore, in terms of the results of determining environmental physical-chemical criteria and heavy metal concentration, the soil in the studied area can be used for health safe vegetable production. The research results not only serve as a basis for assessing the quality of the soil environment for safe healthy vegetable planting, but also serve as a scientific basis for the authors to propose a number of appropriate solutions to protect and improve the quality of vegetables, land environment protection, contributing to the planning and sustainable use of agricultural lands for the studied area.

Assessing the livestock raising and waste treatment of small-scale pig farming households in Binh Dinh Province

Nguyen Thuy Lan Chi — 2023-12-31

Small-scale pig farming played a important role and brought effective economic benefits to households. However, it also caused risks to environmental quality, including air, soil and water, that farmers did not understand or paid enough attention. This study aimed to describe environmental parameters, livestock raising activities and waste treatment of small-scale pig farming households in Binh Dinh province. The samples for air, wastewater, groundwater and surface water analysis were surveyed at 05 sites of the project area in June and September of 2023 to evaluate the environmental quality status in study area. For the small-scale pig raising activities, data was investigated at 100 households in 04 Districts/Towns. The results indicated that the wastewater parameters collected at the pig farming households, with of TSS (300 – 1,500 mg/L), BOD5 (742 – 3,465 mg/L), COD (1.808 –10,320 mg/L), T_N (39 – 463 mg/L) and Coliform (3.6 x10⁵ – 9.2 x10⁵ MPN/100 mL). These findings exceeded from 1.5 – 160 times the allowable concentration for discharge into water sources that could not be used for domestic water supply purposes (QCVN 62:2016/BTNMT). These wastes have polluted surrounding surface water sources, furthermore, there was a risk of contaminating the air quality, soil environment, and groundwater layers. The survey results on pig raising activities showed that most households (69%) desired to keep the current scale, only 6% of farmers hoped to increase the scale. In addition, up to 25% of total farmers wanted to reduce the farming scale because they were afraid of risks in the pig raising process. Nowadays, small-scale pig farming households in Binh Dinh province have been aware of the pollution problem and taken preliminary measures for the waste treatment generated, of which building biogas digesters (without manure separation) accounted for the highest proportion (89% of the total number of households). However, the pollutant content of treated wastewater has been still high and exceeded the allowable discharge concentration. Most pig raising households would like to be guided to invest in building their own wastewater treatment systems, but investment costs were still a significant barrier for households in this production activity. Research results showed that the high application opportunities when popularizing the construction of wastewater treatment models for small-scale pig raising households in Binh Dinh province.

Fluctuations in rice yields and productivity in the comprehensive flood control dike area of the upstream VietNam Mekong Delta: A case study of An Giang province

Huỳnh Thị Ngọc Tươi — 2023-12-31

Full dyke system has greatly benefited farmers in cultivating triple rice cropping during flooding seasons in the Mekong Delta. Although tripple rice cropping brings benefits, its full dyke system has changed flooding situation in the Mekong Delta and stopped sediments to enrich the rice fields. Long-term intensive rice cultivation leads to soil degradation, which is one of the causes of reduced rice yields and productivity. The study aims to evaluate the changes in triple rice yield and productivity under the effect of a flood control dyke system in An Giang province. Spatial data on flooding and land use derived from MODIS satellite imagery was analyzed and compared with data of flood extension from Radar satellite product, while land use data from MODIS was verified with cultivation rice data from Statistical Yearbooks issued by An Giang province from 2000 - 2020. The result of this study shows that the flooded area decreased by 65.92%, creating conditions for farmers to expand the triple rice cropping area by 46,61%. However, the area of triple rice cropping in the phase of 2011 - 2020 has reduced 13.90%. As a result, the production decreased by 9.82% in the proportion of rice in the whole year and a 0,83 ton/ha decreased in comparison with the period when the dyke system was still under construction (2000-2011). In addition, triple rice cropping was practised in the protected flood control dyke systems in the upstream districts has higher average yields than those in the downstream districts (5.60 tons/ha compared to 5.40 tons/ha). The research shows a positive correlation between the increase in the area of flood control dyke system and the yield and production of triple rice cropping. The research results provide insights for researchers and policymakers in the region to adapt appropriate plans to minimize flood risks and ensure livelihood stability for farmers in the flood control dyke system in the upstream area, e.g. An Giang province, of the Mekong delta.