Thai Environmental Engineering Journal

Environmentally Friendly Manufacturing of Fly Ash Geopolymer Mortar

Tue, 24 Dec 2024 00:00:00 +0700

This research presents the environmentally friendly manufacturing (green manufacturing) of geopolymer mortar, focusing on the unit weight and compressive strength of geopolymer made from Mae Moh fly ash from Lampang Province. Graded sand in a dry condition was used in this investigation. The fly ash/sand ratio was set at 1:2.75. Sodium hydroxide (NaOH) and potassium hydroxide (KOH) solutions were used at concentrations of 2.5, 5, and 7.5 molars (M), respectively. The ratios of Na₂SiO₃/NaOH and Na₂SiO₃/KOH were controlled at 0.5:1, 1:1, and 2:1, respectively. The solution/fly ash ratio was set at 0.6. The temperatures for curing the geopolymer mortar were controlled at 30°C and 60°C, respectively. The compressive strength test of geopolymer mortar was conducted at the ages of 7, 28, and 56 days, respectively. Tap water was used to mix the geopolymer mortar, similar to that used in cement mortar for strength comparison.

The results indicated that the concentration of the alkaline solution can affect the rate of polymerization. Higher concentrations can lead to faster polymerization such as at a NaOH concentration of 7.5 M and a Na₂SiO₃/NaOH ratio of 1:1, a maximum compressive strength of 210 ksc was obtained at 56 days of testing (after 1 day of curing at 60°C). Similarly, at a KOH concentration of 7.5 M and a Na₂SiO₃/KOH ratio of 1:1, a maximum compressive strength of 240 ksc was obtained at 56 days of testing (after 1 day of curing at 60°C). Comparatively, the compressive strength of samples mixed with KOH solution was a bit higher than those mixed with NaOH solution. Furthermore, elevated curing temperatures can accelerate the geopolymerization process, enhancing strength in a shorter time frame. As it was clearly found that heat curing at 60°C provided higher compressive strength than curing at room temperature (30°C). Nevertheless, due to the aspect of environmentally friendly manufacturing of geopolymer mortar, a curing temperature close to room temperature (approximately 30°C) can yield a reasonable compressive strength within the range of 160-220 ksc, when stored in air for duration of 56 days, therefore, lengthening the curing time results in higher strength, as it allows more complete polymerization which contributes to the density and interconnectivity of geopolymer structure.

Synthesis of Cassava Rhizome Biochar for Methomyl Adsorption

Tue, 24 Dec 2024 00:00:00 +0700

This research aims to study the synthesis of biochar from cassava rhizomes and the factors involved in the adsorption of methomyl. Methomyl is a carbamate pesticide. The factors of interest in the synthesis of biochar include the pyrolysis temperatures of 300, 400, and 500 °C and the pyrolysis time of 2.5 hours under nitrogen gas conditions, and the obtained biochar was modified with phosphoric acid to increase the efficiency of adsorption. The synthesized biochar was examined using various techniques, including CHN/O, BET, SEM, FTIR, and XTM. The factors of interest in the adsorption study include contact time, agitation speed, and pH value. The study found that the temperature and duration of pyrolysis affect biochar quality. The selected biochar was obtained at 500 °C for 2.5 hours with the highest %C of 78.149 and the lowest H/C of 0.026, similar to other research studies. The biochar is of high quality, has a stable C ratio, and a low H/C. A higher carbon content results in more stable biochar. Modifying biochar with phosphoric acid results in an increase in its physical and chemical properties. The specific surface area from BET measurement and the average pore diameter increased from 2.29 to 3.39 m²/g and 1.57 to 6.54 Å, respectively. For methomyl adsorption experiments, it was found that equilibrium was reached after 180 minutes. The rotational speed and pH value affected the adsorption efficiency. The optimum condition for methomyl adsorption was an agitation speed of 200 rpm because it achieved the highest adsorption efficiency of 19.7%. Further agitation speed experiments revealed that turbulence is critical in controlling the solid-liquid mass transfer mechanism. The pH condition that resulted in the best adsorption was pH 3, with an efficiency of 27.90% and the highest adsorption capacity (qe) at 2.79 mg/g.

Characterizing Particle Number Size Distributions and Source Contribution for Public Elementary School Classrooms in Bangkok

Hnin Phyu Phyu Aung, Win Trivitayanurak — Tue, 24 Dec 2024 00:00:00 +0700

This study provides crucial information on indoor air pollution in public elementary schools in Bangkok, highlighting the substantial impact it has on the health and learning conditions of students, particularly in view of the city's rapidly urban expansion. The research examines particle size distributions (PSD) in four urban schools using the scanning mobility particle sizers (SMPS) and the optical particle sizers (OPS) to cover particle size range of 10 nm to 10 microns. Measurement covered class hours on weekdays and experiments on the weekends. Throughout the study, outdoor particle number concentration (PNC) was significantly higher than indoor levels.

On weekdays, the indoor 1-hour mean PNC at Site S4 reached ‌23,182 cm⁻³ as a highest level among others, classified as a High PNC level according to WHO good practice guidelines. This suggests substantial internal sources, inadequate ventilation, and the impact of nearby traffic and school activities. Similarly, during weekend measurements, Sites S1 and S3 also reached High PNC levels, with concentrations of 27,663 cm⁻³ and 29,534 cm⁻³, respectively. Peaks in PNC were directly linked to the use of cleaning products containing volatile chemicals, underlining the pronounced impact of these activities on indoor air quality. The weekday indoor particle number size distribution (PNSD) exhibited a single-mode distribution, significantly influenced by routine class activities and student movements. Over the weekend, the indoor PNSD across all sites showed fluctuations corresponding to various experimental setups involving changes in ventilation and cleaning activities. This study underscores the necessity of strategic indoor air quality management in schools, aiming to reduce exposure to high PNCs, improve indoor air quality in classrooms, and provide better educational settings for children in increasingly urbanized regions. Effective strategies might include enhanced ventilation, controlled cleaning practices, and real-time monitoring of PNC and PNSD to maintain a healthy educational environment.

Sustainable Tourism Management Using Waste Minimization Approach: A Case Study of an Elephant Park in Chiang Mai

Palita Kunchorn, Alice Sharp — Tue, 24 Dec 2024 00:00:00 +0700

Elephant Park is one of the famous tourist destinations in many districts of Chiang Mai. The growth of tourism in elephant parks has a positive effect on national and local economies. However, tourist activities create solid waste, food waste, and elephant dung. Without proper waste management, environmental issues may arise. Therefore, this research aims to study the current solid waste situation in the elephant park, develop a solid waste management strategy using a waste minimization approach, and implement pilot activities. One of the elephant parks in Chiang Mai was used as a case study. Several methodological approaches have been used in this research, including surveying the elephant park, interviewing stakeholders, collecting solid waste, identifying waste characteristics and streams, improving compost quality from elephant dung, and developing waste separation points. Descriptive statistics and content analysis were used to analyze the data. Finally, all data will be used to construct a sustainable solid waste management strategy for the elephant park. The results showed that the elephant park produces an average waste of 10.84 kg per day from tourist activity. These wastes could be classified into four types, namely organic waste (27.16%), recyclable waste (15.36%), general waste (55.77%), and hazardous waste (1.71%), respectively. A person at the elephant park produces an average of waste at 0.03 kg/day. Waste minimization activities for the two major categories were proposed. It includes waste separation points for recyclables and improvement of compost quality from elephant dung. In addition, all people in the elephant park need to sort their waste correctly before disposal to make it easier to manage and help reduce the amount of waste that goes to landfill. In the future, the researcher recommends conducting follow-up assessments after implementing the management strategy.

Workplace Environment and Health Effects of Ribbed Smoked Sheet Factory: A Case Study of Thung Yai Rubber Fund Cooperative

Tue, 24 Dec 2024 00:00:00 +0700

This study investigates environmental conditions and their impact on worker health within the Thung Yai Rubber Fund Cooperative, specifically focusing on the Ribbed Smoke Sheet factory. Working area temperature and wind velocity were systematically monitored at two locations using digital thermometers and anemometers, respectively. Air quality parameters, including total dust, carbon dioxide (CO₂), and oxygen (O₂) levels, were assessed using real-time monitoring equipment. A qualitative approach was adopted to evaluate adverse health effects experienced by workers, employing standardized questionnaires and comprehensive interviews. The results revealed significant health implications among workers exposed to total dust and an inappropriate working environment over the last three months. Specifically, 53.8% of workers experienced nose congestion and stuffy nose; 46.2% experienced a runny nose; 30.8% experienced sore eyes, itchy eyes, body rash, and body itching; 15.4% experienced red eyes; 38.5% experienced sore throat, coughing, mucus, and fatigue; 23.1% experienced difficulty breathing; and 7.7% experienced rapid heartbeat and wheezing. Furthermore, the study concluded that workplace temperatures exceeded prescribed standards, and oxygen concentration levels is slightly higher than Occupational Safety and Health Administration (OSHA) standards. These findings should provide the intervention to address hazardous working conditions, including regulating temperature to safeguard worker health and well-being. Continuous monitoring and enforcement of safety standards are imperative to prevent future respiratory ailments and ensure a safe working environment conducive to optimal productivity and employee welfare within the Thung Yai Rubber Fund Cooperative.

Natural Attenuation of Arsenic in Natural Wetlands at Thung Kham Gold Mine Wang Saphung District, Loei Province

Apinya Tonguntang, Netnapid Tantemsapya, Chatpet Yossapol, Vanlop Thathong — Tue, 24 Dec 2024 00:00:00 +0700

The gold mining operations in Khao Luang Sub-district, Wang Saphung District, Loei Province, have had a significant impact on the surrounding environment, leading to arsenic contamination. The objective of this research was to examine the extent of arsenic contamination in the natural wetland area and Pu Leuk Creek, adjacent to the Thung Kam gold mine. The study focused on sediments samples taken from three points along the creek: upstream, middle, and downstream, at depths ranging from 0 to 150 cm. The findings revealed that concentrations of total arsenic in the sediment at the upstream, middle, and downstream points ranged from 160.1-1,112 mg/kg, 49.79-1,911 mg/kg, and 0.39-1,080 mg/kg, respectively. For As(III), the concentrations ranged from 28.63-320.40 mg/kg, 0-1,032 mg/kg, and 0-544.60 mg/kg, respectively. For As(V), the concentrations ranged from 115.49–853.70 mg/kg, 8.5-879 mg/kg, and 0–586.5 mg/kg, respectively. Most of these values exceed the standard threshold for soil quality for agricultural use (25.00 mg/kg) set by the National Environmental Board in 2021. The highest concentrations of arsenic were found at the middle point of the creek, possibly due to its proximity to the mineral waste pond in the gold mining area. Additionally, the highest concentrations of arsenic were found at depths of 0–40 cm, indicating that depth levels affect the accumulation of arsenic in the sediment. The analysis of the elemental composition in the sediment using the Energy Dispersive X-ray Fluorescence (EDXRF) technique revealed that the chemical constituents in the sediment include Al, Si, K, Ca, Ti, Mn, Fe, Cu, Zn, As, Rb, Zr, and Pb. The predominant mineralogical components in the sediment are quartz (SiO₂) and hematite (Fe₂O₃). Regarding the analysis of the forms of arsenic in the sediment, it was observed that the concentration of As(V) was higher than that of As(III). This suggests that As(V) may have been absorbed or precipitated along with other mineral elements in the sediments. The presence of arsenic exceeding the standard limits in this area, as mentioned above, may have adverse health effects on the people residing near the gold mining area.

Effects of an Electrokinetic Barrier to Inhibit Heavy Metal Absorption in Rhizophora mucronata Seedlings

Ivan de La Grange, Jenyuk Lohwacharin, Chadtip Rodtassana — Tue, 24 Dec 2024 00:00:00 +0700

Developing an electrokinetic barrier to hinder mangrove seedlings from heavy metal absorption is a novel technology for conducting mangrove reforestation within contaminated environments. In this study, the objectives were to discover a hydroponic solution that offers favorable plant responses for mangrove seedlings and to investigate this environment under a micro-electric field and/or a heavy metal (HM) presence. For 15 weeks, Rhizophora mucronata seedlings were grown hydroponically in containers encompassing unique conditions: the control, 1 ml nutrient solution (NS)/L, and 1.5 ml NS/L. Seedlings from 1.5 NS had the greatest mean regarding the number of roots (p < 0.05), but the 1 mL NS had the largest mean for root diameter (p < 0.05), along with thicker roots and more leaf development also observed. An electrokinetic experiment was performed to compare a direct current of 10 V/m and 20 V/m in a HM solution consisting of 1 ml NS/L with ZnSO₄·7H₂O (400 mg/L), CrCl₃·6H₂O (400 mg/L), and CdCl₂·2.5H₂O (1.5 mg/L). 10 V/m caused a statistically significant migration for Cd and Cr, whereas 20 V/m was required for Zn, respectfully. When comparing the nitrate to phosphate ratios and pH between HM and HM plus electric current (EC), the margins of difference were less substantial for 10 V/m than 20 V/m. It can be concluded that 1 ml NS/L and 10 V/m is preferable for future electrokinetic barrier design, but because HMs affect the pH values of hydroponic solution greater than natural soil conditions, the HM concentration must be reduced for mangrove tolerability accordingly.

Performance of Pilot-scale Constructed Wetlands for Treating Paper Mill Effluent

Netnapid Tantemsapya, Patcharin Racho, Chatpet Yossapol — Tue, 24 Dec 2024 00:00:00 +0700

Wastewater discharged from the paper industry generates substantial volumes, ranging between 75 and 225 m³ per ton of product, containing high levels of organic content (COD 480-4450 mg/L), chloride (80-980 mg/L), and a variety of volatile fatty acids (approx. 950 mg/L), cellulose (approx. 1,200 mg/L). The objective of this study was to investigate the efficiency and reaction coefficients of the free water surface flow constructed wetlands (FWS CWs) for removing pollutants such as color, dissolved solids, suspended solids, chemical oxygen demand (COD), biochemical oxygen demand (BOD₅), and nitrogen (TKN). Three pilot-scale units were established, each containing sand as the media and planted with (1) Narrowleaf cattail (Typha angustifolia L.), (2) Loop-root mangrove (Rhizophora mucronata Lam.), and (3) Unplanted control. Upon evaluating the system's performance, it was observed that the FWS CWs effectively reduced contaminants in the factory effluent, particularly color, COD and TKN. The color removal efficiency ranged from 31.15-93.55% (56.86+18.31), 17.86-89.25% (54.30+21.39%), and 27.87-91.40% (58.11+18.84%) for control, cattail, and mangrove unit, respectively. Regarding COD removal, the efficiencies ranged from 31.15-93.55% (56.86+18.31), 17.86-89.25% (54.30+21.39%), and 27.87-91.40% (58.11+18.84%) for control, cattail, and mangrove unit, respectively. Both COD and color removal efficiency presented no statistically significant differences observed among the three units (P > 0.05). The removal efficiency of TKN was 40.00 and 85.74%, 20.00 and 85.71%, and 80.00% and 85.71% for control, cattail, and mangrove unit, respectively. The reaction kinetics of color removal appear to align with both Plug Flow Reactor (PFR) and Continuous Stirred Tank Reactor (CSTR) models. Rate constants for color removal were calculated for the control and mangrove units, as no color removal was observed in the cattail unit. For the mangrove unit, the first-order reaction rate constants were 0.021 d⁻¹ for the PFR model and 0.023 d⁻¹ for the CSTR model, while for the control unit, they were 0.030 d⁻¹ for the PFR model and 0.035 d⁻¹ for the CSTR model. COD reduction can be described by the CSTR model, with first-order reaction rate constants of 0.140 d⁻¹ for the control unit, 0.131 d⁻¹ for the cattail unit, and 0.143 d⁻¹ for the mangrove unit.