Estimation of forest Carbon Stocks in Ba Be National Park, Bac Kan province, Vietnam

Climate change and an increase in the greenhouse effect are a matter of global concern. One of reasons for this phenomenon is the increase in greenhouse gases, especially CO2. Therefore, the authors investigated CO2 absorption from forests of 45 plots in Ba Be National Park, characterized by 3 forest states as rich, medium and poor forest, rehabilitated forest after exploitation to estimate carbon sequestration of the forest. In which, the carbon stock of rich forest reaches 273.17 tones/ha, the medium forest is 136.23 tones/ha and the poor forest, rehabilitated forest is 42.06 tones/ha. With a forest growth rate of 1.8% per year, the carbon sequestration in Ba Be National Park for 3 forest states is about 16,499 tones per year. This will contribute to improve environmental quality, reducing greenhouse gas emissions and creating a scientific basis for managers to develop a payment mechanism of forest carbon sequestration services

Application of modified zeolite in the remediation of heavy metal in contaminated soil: a short review

This paper explores the significant potential of modified zeolites in various industries, emphasizing their role in promoting environmental sustainability. The study highlights the applications of modified zeolites in heavy metals in contaminated soil, showcasing their ability to address environmental pollution and enhance resource utilization. The research underscores the importance of fine-tuning zeolite modification techniques to achieve precise structural control and stability. Challenges related to the impact of even minor modifications on performance and the long-term stability of modified zeolites are acknowledged. Despite these challenges, the paper anticipates a promising future for modified zeolites, with advancements in materials science and nanotechnology expected to pave the way for innovative solutions in contaminated soil

Treatment of leachate by combining PAC and UV/O3 processes: Research article

The landfill leachate is commonly treated for non-biodegradable organic matters, ammonia and colour. Experimental investigations using polyaluminium chlorite (PAC) and UV/O3 have been conducted for the determination of optimal pH value, reaction time and PAC concentration for the removal of chemical oxygen demand (COD) and colour. In pre-treatment coagulation stages, the highest COD and colour removal efficiencies were observed at the concentration of PAC ≥ 3,000 mglG1 and pH values between 7 and 8. However, these experiments also indicated significant removal efficiency for PAC starting with concentrations of 1,500 mglG1. The efficiency of COD and colour removal were approximately 30% and 70%, respectively. Similar efficiencies have been observed also during the second treatment stage where UV/O3 processes were used to treat coagulated leachate. After UV/O3 application, the pH of leachate reached the optimum value of 7.5 whereas the highest COD and colour removal efficiency was 55% and 72%, respectively, and the optimal reaction time was achieved after 80 min.Nước rỉ rác sinh ra từ bãi chôn lấp chất thải rắn cần được xử lý các thành phần chất hữu cơ khó phân hủy sinh học, xử lí amoni và độ màu. Một số kết quả thử nghiệm về xử lý COD và màu của nước rỉ rác bằng việc sử dụng phương pháp keo tụ với PAC và quá trình UV/O3 đã được thực hiện cùng với việc xác định các giá trị pH tối ưu, thời gian phản ứng và nồng độ PAC tối ưu. Hiệu suất xử lý cao nhất đạt được khi nồng độ của PAC ≥ 3.000 mg/l, pH trong khoảng từ 7 đển 8 trong giai đoạn tiền xử lý. Tuy nhiên, hiệu quả loại bỏ COD và màu bắt đầu tăng rõ khi nồng độ PAC từ 1.500 mg/l trở lên. Hiệu quả loại bỏ COD và màu tương ứng là khoảng 30% và 70%. Các giá trị pH này phù hợp cho quá trình phản ứng UV/O3 được sử dụng sau giai đoạn keo tụ. Sau quá trình xử lý bằng hệ UV/O3, pH của nước rỉ rác tối ưu được xác định là 7,5 (hiệu suất xử lý COD và màu cao nhất tương ứng là 55% và 72%), thời gian phản ứng tối ưu là 80 phút

Treatment of medical solid waste using an Air Flow controlled incinerator

In this study, air flow controlled incinerator (AFCI) was used to treat medical solid waste in Vietnam. The experiment was conducted with solid waste samples that was weighed approximately 2.1–3.3 kg/h and had moisture content of 2.8–11.7%. The results showed that an increase in the air flow rate during the drying process accelerated the combustion time by 10–20%, and the optimal air low rate was 1.1 m/s. The combustion time varied from 0–45 min. The highest temperatures recorded in the drying chamber, carbonisation chamber and combustion chamber after 25–35 min of operation were varied from 195o C, 775o C and 1275o C, respectively. The temperature of the stack was from 33–68o C after the treatment by the wet scrubber using 20% NaOH solution. The combustion capacity was 77.3–87.5%. The experimental results revealed the AFCI process advantages including low operation cost and suitability for treating hazardous waste on a small scale

Treatment of medical solid waste using an Air Flow controlled incinerator

In this study, air flow controlled incinerator (AFCI) was used to treat medical solid waste in Vietnam. The experiment was conducted with solid waste samples that was weighed approximately 2.1–3.3 kg/h and had moisture content of 2.8–11.7%. The results showed that an increase in the airflow rate during the drying process accelerated the combustion time by 10–20%, and the optimal airflow rate was 1.1 m/s. The combustion time varied from 0–45 min. The highest temperatures recorded in the drying chamber, carbonisation chamber and combustion chamber after 25–35 min of operation were varied from 195°C, 775°C and 1275°C, respectively. The temperature of the stack was from 33–68°C after the treatment by the wet scrubber using 20% NaOH solution. The combustion capacity was 77.3–87.5%. The experimental results revealed the AFCI process advantages including low operation cost and suitability for treating hazardous waste on a small scale

Treatment of medical solid waste using an Air Flow controlled incinerator

In this study, air flow controlled incinerator (AFCI) was used to treat medical solid waste in Vietnam. The experiment was conducted with solid waste samples that was weighed approximately 2.1–3.3 kg/h and had moisture content of 2.8–11.7%. The results showed that an increase in the air flow rate during the drying process accelerated the combustion time by 10–20%, and the optimal air low rate was 1.1 m/s. The combustion time varied from 0–45 min. The highest temperatures recorded in the drying chamber, carbonisation chamber and combustion chamber after 25–35 min of operation were varied from 195o C, 775o C and 1275o C, respectively. The temperature of the stack was from 33–68o C after the treatment by the wet scrubber using 20% NaOH solution. The combustion capacity was 77.3–87.5%. The experimental results revealed the AFCI process advantages including low operation cost and suitability for treating hazardous waste on a small scale

Magnetic Fe3O4 Nanoparticle Biochar Derived from Pomelo Peel for Reactive Red 21 Adsorption from Aqueous Solution

In this study, Fe3O4 nanoparticle-loaded biochar derived from the pomelo peel (FO-PPB) was synthesized and applied as an affordable material for the adsorption of Reactive Red 21 (RR21) in an aqueous solution. The characteristics of FO-PPB were evaluated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), Raman spectra, Fourier transform infrared spectra (FTIR), and Brunauer–Emmett–Teller (BET) surface area. The adsorption process of FO-PPB with RR21 was evaluated through batch experiments to examine various parameters including solution pH, contact time, adsorbent dose, initial RR21 concentration, and solution temperature. Results show that FO-PPB produced by the impregnation ratio between iron (Fe) and pomelo peel biochar (PPB) of 5 : 1 (w/w) had the best adsorption performance. The adsorption capacities of PPB and FO-PPB at optimum experimental conditions (solution pH 3, contact time of 60 min, solution temperature of 40°C, initial RR21 concentration of 300 mg/L, and adsorbent dose of 2 g/L) were 18.59 and 26.25 mg/g, respectively. The adsorption isotherms of RR21 on PPB and FO5-PPB were described well by Langmuir and Sips models with high R2 values of 0.9826 and 0.9854 for FO5-PPB and 0.9701 and 0.9903 for PPB, respectively. The obtained data also well matched the pseudo-first-order and pseudo-second-order models with R2 values ≥ 0.96. Chemisorption through sharing or electronic exchange was determined as the main adsorption mechanism

Coconut Shell Activated Carbon/CoFe2O4 Composite for the Removal of Rhodamine B from Aqueous Solution

Coconut shell activated carbon loaded with cobalt ferrite (CoFe2O4) composites (CAC/CoFe2O4) was synthesized via the single-step refluxing router method to manufacture adsorbents. The adsorbents were then applied to remove Rhodamine B (RhB) from aqueous environments via adsorption. The properties of coconut shell activated carbon (CAC) and CAC/CoFe2O4 were investigated through the usage of electron microscopic methods (SEM: Scanning Electron Microscopy, EDS: Energy Dispersive X-ray), powder X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). A series of batch experiments were implemented to evaluate the influences of various experimental parameters (initial pH, RhB concentration, contact time, and dosage of CAC/CoFe2O4) on the adsorption process. It was found that CoFe2O4 was successfully attached to activated carbon particles and had the suitable adsorption capacity for RhB at a molar ratio of 1 : 2:200 corresponding to the Co : Fe:CAC order. The removal efficiency and adsorption of RhB were optimal at a pH level of 4. The maximum adsorption capacity was 94.08 mg/g at an initial concentration of 350 mg/L and adsorbent dosage of 0.05 g/25 mL. Freundlich and Langmuir's models fitted well with the results obtained from the experimental data. The pseudo-second-order model also suited the most for RhB adsorption with the most remarkable correlation coefficient (R2 = 0.934). The adsorption process was controlled by a chemisorption mechanism through electrostatic attraction, hydrogen bonding interactions, and π-π interactions

Immobilization of heavy metals in contaminated soil after mining activity by using biochar and other industrial by-products: the significant role of minerals on the biochar surfaces

Heavy metal contamination of crop lands surrounding mines in North Vietnam is a major environmental issue for both farmers and the population as a whole. Technology for the production of biochar at a village and household level has been successfully introduced into Vietnamese villages. This study was undertaken to determine if rice straw biochar produced in simple drum ovens could remediate contaminated land. Tests were also carried out to determine if biochar and apatite mixed together could be more effective than biochar alone. Incubation trials were carried out over 90 days in pots to determine the total changes in exchangeable Cd, Pb and Zn. Detailed tests were carried out to determine the mechanisms that bound the heavy metals to the biochar. It was found that biochar at 5% (BC5) and the mixture of biochar and apatite at 3% (BCA3) resulted in the greatest reduction of exchangeable forms of Cd, Pb and Zn. The increase in soil pH caused by adding biochar and apatite created more negative charge on the soil surface that promoted Pb, Zn and Cd adsorption. Heavy metals were mainly bound in the organic, Fe/Mn and carbonate fractions of the biochar and the mixture of biochar and apatite by either ion exchange, adsorption, dissolution/precipitation and through substitution of cations in large organic molecules