Thai Environmental Engineering Journal

Estimation of Biomass Carbon Storage and Ecological Values of Urban Forest at Chulalongkorn University and its Implications for Carbon Management

2026-05-07T16:11:59+07:00

Rapid urbanization and increasing greenhouse gas (GHG) emissions over recent decades have intensified climate change and air pollution. However, limited studies have quantified carbon storage and ecosystem services of tropical university campus forests using large-scale inventories and site-specific environmental data, particularly in Southeast Asian megacities such as Bangkok. This study aims to quantify biomass carbon storage and assess key ecosystem services of the urban forest at Chulalongkorn University (CU) and to evaluate their implications for campus-level carbon management. In this assessment, a total of 2,394 trees from a complete tree inventory collected in 2021 and 2022 were analyzed. Biomass carbon storage was estimated using both allometric equations and i-Tree Eco model as complementary approaches under different assumptions and to reflect potential variation between two methods for open-grown urban trees. In addition, the model was employed to evaluate major regulating ecosystem services, including carbon sequestration,
air pollution removal, avoided stormwater runoff and oxygen production. To improve local representativeness of model inputs, site-specific hourly meteorological and air pollution data were incorporated. The results revealed that total biomass carbon storage was 1,914.47 tons (7,019.01 tCO₂e) based on manual calculations, whereas the i-Tree Eco model estimated a higher value of 2,796 tons. Furthermore, campus trees were found to sequester 97.81 tons of carbon annually and remove approximately 2.15 tons of air pollutants per year. They also contributed to stormwater management by reducing runoff by 6,460 m³ annually and produced about 260.8 tons of oxygen. Among all species, large and dominant trees in the study area, particularly Albizia saman, contributed the most to overall ecosystem services. The findings highlighted the role of urban forest in supporting carbon neutrality goals, tree conservation prioritization, green infrastructure planning and environmental management of the university, while demonstrating their broader value as nature-based solutions for climate mitigation and urban resilience.

Assessment of Pollutant Dispersion in Emergency Scenarios at an Oil Terminal: A Case Study Using the ALOHA Model

2026-05-16T14:55:56+07:00

This study assesses pollutant dispersion and associated safety impacts resulting from kerosene leakage at oil terminal facilities located in Bangkok and Samut Prakan, Thailand, using the ALOHA (Areal Locations of Hazardous Atmospheres) software to simulate vapor dispersion and fire scenarios. The assessment focused on evaluating the hazard distances of the Flammable Area of Vapor Cloud, Toxic Threat Zone, and Thermal Radiation from Pool Fire under different meteorological conditions. A total of ten simulation scenarios were simulated, consisting of seven scenarios in Bangkok (Scenario 1.1–1.7) and three scenarios in Samut Prakan (Scenario 2.1–2.3).

The results suggest that the flammable vapor cloud area remained relatively constant across all scenarios, hazard distances of approximately 22 m in Bangkok and 23 m in Samut Prakan. This finding suggests that kerosene has a low evaporation rate, causing the flammable vapor cloud to remain confined near the leakage source within the bund wall area and to be minimally influenced by meteorological conditions.

For the Toxic Threat Zone, Samut Prakan exhibited significantly greater impact distances than Bangkok. The AEGL-1 distances ranged from 55–60 m and AEGL-2 distances ranged from 24–26 m in Samut Prakan, whereas Bangkok showed AEGL-1 distances of 33–37 m and AEGL-2 distances of 22–23 m. These differences may be explained by the larger fuel storage capacity, larger tank dimensions, and greater containment areas in Samut Prakan, which may have promoted higher evaporation and vapor accumulation in the atmosphere.

The assessment of Thermal Radiation from Pool Fire revealed substantially larger impact distances in Samut Prakan compared with Bangkok. Thermal radiation distances at 10 kW/m² were approximately 95–96 m in Samut Prakan and 63–64 m in Bangkok. At 5 kW/m², the distances were approximately 134–135 m in Samut Prakan and 90–91 m in Bangkok, while at 2 kW/m², the distances were approximately 208–210 m in Samut Prakan and 140–142 m in Bangkok. These results suggest that Thermal Radiation from Pool Fire may represents the most extensive hazard compared with the Flammable Area of Vapor Cloud and Toxic Threat Zone.

Overall, Samut Prakan exhibited greater hazard distances for all parameters than Bangkok, which may be associated with its larger storage tanks, greater fuel inventory, and larger containment areas, potentially resulting in larger fuel puddles and higher vapor generation. The findings also suggest that the dispersion behavior of kerosene in this study may resemble quasi-heavy gas behavior which may cause vapor clouds to accumulate near ground level and generate hazards primarily within the near-field region close to the leakage source. In contrast, the dominant hazard associated with the incident was Thermal Radiation from Pool Fire, which produced the widest impact area.

Anthropogenic CO and NOx Emission Inventory in Thailand

2026-06-19T17:51:52+07:00

Air pollution remains a critical environmental issue in Thailand, particularly in relation to Carbon Monoxide (CO) and Nitrogen Oxides (NO_x), which are closely linked to transportation, industrial activities, biomaass burning, and energy consumption. Although CO and NO_x concentrations in Thailand may not always exceed national air quality standards, they are critical primary precursors for secondary pollutants, particularly tropospheric ozone [5], making the monitoring of their emission inventories essential for effective air quality management. This study aimed to investigate the spatial distribution, emission sources, and seasonal variability of anthropogenic CO and NO_x emissions in Thailand during 2014–2024 using the CAMS-GLOB-ANT v6.2 emission inventory obtained from the ECCAD database. It should be noted that this dataset covers strictly anthropogenic sources and agricultural open burning, and does not include natural forest fire emissions. The results indicate that CO and NO_x exhibit similar spatial distributions, with relatively high emissions concentrated in the Central and Eastern regions, particularly in major urban, industrial, and transportation corridors. In contrast, emissions in the Northeastern region are more spatially dispersed, whereas the Northern and Southern regions display localized or corridor-like patterns influenced by topography and settlement structure. Road transportation was identified as the dominant source of emissions in most regions, while agricultural waste burning, industrial processes, refineries, and power generation contributed differently depending on regional economic characteristics. Monthly analysis showed that both CO and NO_x emissions increased from March to May, with peak levels in May, reflecting the combined effects of late dry-season biomass burning and meteorological conditions favorable to pollutant accumulation. Overall, the findings demonstrate that anthropogenic CO and NO_x emissions in Thailand are strongly shaped by regional economic activities, land-use characteristics, and seasonal factors, underscoring the need for region-specific air pollution management strategies.

A Preliminary Study on the Composition, Quantity, and Management of Solid Waste from Tourism at Kaw Kwang Beach, Koh Lanta District, Krabi Province, Thailand

2026-06-29T09:04:04+07:00

This preliminary study explores the composition, quantity, and management of solid waste resulting from tourism activities at Kaw Kwang Beach, located in Ko Lanta District, Krabi Province, Thailand. The study area was divided into three zones: Zone A (pine forest), Zone B (central beach), and Zone C (hotel frontage). Field data were collected ten times during April–May 2024, following the International Coastal Cleanup (ICC) methodology. A total of 3,332 waste items, weighing 66.32 kilograms, were recorded. The majority of the waste was general waste, followed by recyclable and hazardous waste. Common items included wooden skewers, plastic bags, and cigarette butts, reflecting tourist behavior and coastal activities. Statistical analysis using ANOVA and Tukey HSD revealed a significant difference in waste quantity in Zone B compared to Zones A and C. The current waste management practices were found to be non-compliant with the Ministerial Regulation on Sanitation B.E. 2560 (2017), with issues such as lack of waste separation, uncovered bins, and uncontrolled landfill disposal. Despite these challenges, some waste items, such as plastic bottle caps, were creatively repurposed into flower pots by local schools. The study recommends promoting plastic reduction, enhancing community and tourist education, and improving waste management systems to protect the coastal environment and support sustainable tourism.

Assessment of Air Quality Index and Potential Health Risks Using Meteorological Parameters in Chonburi Province, Thailand

2026-07-07T07:23:51+07:00

This study assessed seasonal variations in air pollutant concentrations, air quality index (AQI), meteorological influences, and inhalation health risks in an industrially influenced area of Chonburi Province, Thailand, during 2019–2021. Monthly concentrations of NO₂, O₃, PM₁₀, and PM_2.5 were analyzed by season. AQI was calculated as a screening-level indicator using available monitoring data, excluding SO₂ and CO because complete data were unavailable. Associations between AQI and meteorological variables were examined using Pearson correlation and regression analyses. Non-carcinogenic inhalation risk was assessed using hazard quotient (HQ) values based on a screening-level concentration-based approach. Pollutant concentrations were generally higher in January and February and lower during June–September. Winter showed the highest
mean concentrations of NO₂, O₃, PM₁₀, and PM_2.5 at 16.37 ± 1.64 ppb, 30.73 ± 3.62 ppb, 60.71 ± 11.68 µg/m³, and 31.33 ± 7.53 µg/m³, respectively. AQI was also highest in winter (73.33 ± 32.69), followed by summer (30.22 ± 5.74) and the rainy season (22.67 ± 5.49). AQI was positively correlated with atmospheric pressure (r = 0.748, p < 0.01) and negatively correlated with relative humidity (r = −0.621, p < 0.01) and rainfall (r = −0.524, p < 0.01). Multiple regression showed that atmospheric pressure was the only significant independent predictor of AQI (B = 8.074, p = 0.004), although this association should be interpreted cautiously due to possible temporal autocorrelation and COVID-19-related activity changes. The HQ results indicated that PM_2.5 and PM₁₀ were the main contributors to potential non-carcinogenic inhalation risk, particularly during winter, when their HQ values exceeded 1.0. NO₂ and O₃ remained below 1.0 across all seasons. These findings support the need for season-specific air quality management, especially particulate matter control during winter pollution episodes in industrial communities.

Legal Development Guidelines for Strengthening the Role of Citizens in Household Waste Management in Thailand

2026-06-26T15:39:07+07:00

This research addresses the critical environmental crisis of household waste in Thailand, where existing legal frameworks fail to regulate public behavior at the source. Although the government has designated waste management as a national agenda, overall waste volume continues to rise due to shifting socio-economic conditions and the lack of mandatory waste segregation. This study aims to examine legal concepts and theories, conduct a comparative analysis of legal measures in the United Kingdom, Sweden, and Japan, analyze impediments within the Thai legal system, and propose developmental pathways to enhance the civic role in waste management. The findings reveal significant structural gaps in Thai law, which primarily focuses on "end-of-pipe" solutions, lacks specific duties for individual households, and relies on inefficient flat-rate
fee structures. Comparative evidence suggests that success in developed nations stems from the exercise of state power through "Command and Control" mechanisms alongside economic incentives. Consequently, this research recommends a comprehensive legal reform, including the enactment of a specialized "Lex Specialis" for household waste. Key proposals include transposing constitutional duties into statutory obligations, transitioning to a "Pay-As-You-Throw" (PAYT) fee model, and implementing Extended Producer Responsibility (EPR) and Deposit-Refund Systems (DRS). These reforms are essential to transform citizens from passive service recipients into active environmental stakeholders, ensuring sustainable resource recovery and social equity.

Green Chemistry Synthesis of Ag/ZnO (ashwater) Using Bark Ash Water and Mango Extract for Enhanced Photocatalytic Degradation of Rhodamine B

2026-06-04T08:33:31+07:00

Ag/ZnO (BAW) was synthesized via a green chemical precipitation method and evaluated as a visible-light photocatalyst for Rhodamine B (RhB) degradation. X-ray diffraction (XRD) analysis confirmed the coexistence of hexagonal wurtzite ZnO and metallic Ag phases, while energy-dispersive X-ray spectroscopy (EDX) verified the presence of Zn, O, and Ag. Scanning electron microscopy (SEM) revealed mixed rod-like and short tubular morphologies. UV–Vis diffuse reflectance spectroscopy demonstrated enhanced visible-light absorption of Ag/ZnO (BAW) compared with ZnO (BAW), and Tauc plot analysis showed a reduction in the optical band gap from 3.16 to 3.10 eV after Ag incorporation. Under visible-light irradiation, Ag/ZnO (BAW) achieved 99.69% RhB degradation within 120 min, compared with 89.51% for ZnO (BAW). The degradation followed a pseudo-first-order kinetic model, with Ag/ZnO (BAW) exhibiting an apparent rate constant of 0.0428 min⁻¹, approximately 2.6 times higher than that of ZnO (BAW) (0.0165 min⁻¹). The addition of 1,4-benzoquinone (BQ) markedly suppressed RhB degradation, suggesting the involvement of superoxide radicals (O₂⁻•) in the photocatalytic mechanism. However, the possible contributions of other reactive species cannot be excluded. The enhanced photocatalytic activity of Ag/ZnO (BAW) is associated with improved light absorption and enhanced photoinduced charge-carrier separation induced by Ag incorporation. These findings demonstrate the potential of Ag/ZnO (BAW) as an efficient and environmentally friendly photocatalyst for dye degradation under visible-light irradiation.

Low-H2 Used Cooking Oil Deoxygenation over a Multifunctional Catalyst: Product-Window Redistribution under H2/Formic Acid Assistance

2026-07-24T14:54:48+07:00

The catalytic conversion of used cooking oil (UCO) to green diesel is not only a conversion problem but also a pathway-control and product-window optimization problem. UCO-derived triglycerides and fatty acids can undergo hydrodeoxygenation (HDO), decarbonylation (DCO), decarboxylation (DCO₂), cracking, and secondary redistribution reactions. In this study, a multifunctional Ni–MgO–Ce_0.6Zr_0.4O₂/γ-Al₂O₃ catalyst was applied for UCO deoxygenation under four hydrogen-supply modes: Catalyst (C), C+H₂, C+FA (formic acid), and combined C+H₂+FA operation. The reactions were compared at 320°C and 350°C, and the products were analyzed by GC-TCD, GC-FID, and DGC/SimDist. The 320°C condition served as a lower-severity reference, where diesel-range products were generally better preserved, whereas 350°C promoted stronger liquid-phase upgrading, higher distillable-product formation, and more effective residue suppression. At 350°C, the distillable fraction below 370°C increased from 78.3% in the catalyst (C) mode to 98.6% in the C+H₂+FA mode, while residue decreased from 21.7% to 1.4%. However, this improvement was accompanied by product lightening, with the diesel-range fraction decreasing from 42.3% to 22.4% and the naphtha-range fraction increasing from 23.8% to 56.8%. Gas analysis showed CO-rich products in the catalyst (C) mode, supporting a strong DCO tendency even without external H₂, while FA-containing modes increased CO_X formation due to both UCO deoxygenation and possible FA decomposition. In the closed reactor, FA-derived gas formation may also have increased internal pressure and contributed to higher reaction severity and product lightening. Overall, the catalyst shows promise for controlled low-H₂ deoxygenation, but secondary cracking and excessive light-product formation must be controlled.