Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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Coupling Wastewater Treatment with Microalgae Biomass Production: Focusing on Biomass Generation and Treatment Efficiency
Get PDFCombination of suitable algae species with wastewater condition is important to achieve high productivity of algae with remarkable removal of contaminants. However, the usage of algae in treating wastewater has not yet to show sufficient removal efficiency when the biomass productivity is extremely enhanced. This review aims to scrutinize and discuss: (1) several promising species for this coupling method; (2) main wastewater characteristics related to the microalgae biomass production and their removal efficiency; (3) metal occurrences and other biotic factors; and (4) constraint of microalgae biomass production and wastewater treatment process. Microalgae such as Chlorella, Spirulina and Scenedesmus are among the most utilized microalgae because of their utilities. Chemical oxygen demand (COD) total nitrogen (TN), and total phosphorous (TP) concentrations affect biomass yield of algae cultivation. Metals occurrences, light intensity and carbon dioxide availability play an important role in process of algae cultivation with diverse optimum levels of each factor. Sufficient but not excess concentration of N and P solely for building biomass and other metabolism activities, mixotrophic condition for algae to digest organic carbon, and heavy metals defense mechanisms are expected to address constraint of biomass generation demand and wastewater treatment efficiency
Risk Factors Affecting Driver Severity of Single- Vehicle Run Off Road Crash for Thailand Highway
Get PDFSingle-Vehicle Run Off Road (ROR) crash has been the leading crash type in terms of frequency and severity in Thailand. In this study, multinomial logit analysis was applied to identify the risk factors potentially influencing driver injury severity of single-vehicle ROR crash using accident records between 2011 and 2017 which were extracted from Highway Accident Information Management System (HAIMS) database. The analysis results show that the age of driver older than 55 years old, male driver, driver under influence of alcohol, drowsiness, ROR to left/right on straight roadway increase the probability of fatal crash, while other factors are found to mitigate severity such as the age of driver between 26-35 years old, using seatbelt, ROR and hit fixed object on straight and curve segment of roadway, mounted traffic island, intersection-related and accident in April. This study recommends the need to improve road safety campaign, law enforcement, and roadside safety features that potentially reduce level of severity of driver involving in single-vehicle ROR crash
Airborne Chloride Intensity and Chloride Ion Penetration into Mortar Specimen in Thailand
Get PDFThe Southern and Eastern parts of Thailand have long coastlines and are located in a hot and humid climate zone. A concrete structure in such environmental conditions tends to deteriorate owing to the corrosion of the steel reinforcement by airborne chloride. The concentration of airborne chloride varies by location and exposure conditions in each country. Thus, when designing concrete structures in such environments, the amount of airborne chloride and the concrete mix proportions should be carefully considered. However, the study of airborne chloride intensity and penetration in Thailand is still limited. This study examined the airborne chloride in the atmosphere in Phuket, Phang-Nga, and Chonburi Province. The amount of airborne chloride was checked every 1–3 months during the test period. Although the distances from the seashore are almost the same in all three locations, the airborne chloride intensity varied owing to the different exposure directions and environmental conditions. Additionally, analysis of mortar specimens with different sources of fly ash installed in Chonburi province to assess the airborne chloride penetration behavior showed that airborne chloride concentration varied with the breaking wave height, rainfall, and varied penetration rate based on the source of fly ash
The Examination of the Effects of Land Use Development on the Balance of Mass Transit Ridership
Get PDFThe balance of the origin–destination (O-D) ridership distribution is an essential characteristic of a sustainable transit system. However, the existing ridership patterns of transit system in many cities are still off-balance, leading to the inefficient utilization of available capacity. As a result, only one direction is overcrowded whereas the other is not. Many literatures suggest that the transit ridership distribution is generally affected by land use around stations due to the different rates of generated and attracted passengers during each period of time. Therefore, the objective of this study is to verify the effects of land use development according to the Transit Oriented Development (TOD) principle on the balance of the O-D ridership along the transit route, as measured by the discrepancies between the numbers of onboard passengers in stations along a single train line. This study has applied the modified Fluid Analogy Method to reflect the travel behavior of mass transit trip distribution. The results show that, to balance the O-D ridership along a linear and stand-alone transit route, the residential areas should be located near the terminal stations with the sub-residential areas in the interval to shorten the distance of home-based trips. The business areas should be densely situated in the middle of mass transit route, while the retail areas should be located dispersedly all along the route. This study has further applied a proposed model with a case study of MRT Blue Line in Thailand to verify the assumption that the location of the mixed-use project along MRT transit route has impacts on the balance of its ridership. This implication can be a guideline for integrating the mixed-use project development and the land use planning to achieve the sustainable transport in the overall perspective
Optimization of Biodiesel Production from Waste Cooking Oil in a Continuous Mesoscale Oscillatory Baffled Reactor
Get PDFIn this study, a mesoscale oscillatory baffled reactor (OBR) was used to synthesize high methyl esters from waste cooking oil (WCO) in an alcoholic hydroxide solution. Preliminary experiments were conducted to screen for appropriate oscillating frequency and reaction temperature for the transesterification of WCO. Response surface methodology (RSM) based on the Box-Behnken design (BBD) was employed to investigate the influence of residence time, amount of catalyst and methanol-to-oil molar ratio on the fatty acid methyl ester (FAME) content of the product obtained from the OBR. Based on the response surface approach, the optimum operating conditions for this process were as: a residence time of 60 s, a catalyst content of 3.0%, and a methanol-to-oil molar ratio of 11. The physical and chemical properties of the product obtained were found to meet the standards
Heat Transfer Coefficient Characteristic Study of Natural Refrigerant with Substitute for R-134a
Get PDFThe wide-spread use of halocarbon refrigerants are making negative impact on Earth. Natural Refrigerant, such as hydrocarbon, is one alternative of several option to use. Mixing hydrocarbon are develop to improve the heat transfer characteristic. For example is, Musicool-134 (MC-134) is a mixture with two major substance of propane and iso-butane. The experimental apparatus is using a microchannel with a diameter of 0.5 mm and length of 0.5 m. The evaporative process was conducted in the experiment. The result of the experiment is that if the high coefficient value then the heat flux value is also high
Impacts of Long Jetties Construction on Shoreline Change at the Western Coast of the Gulf of Thailand
Get PDFPranburi Jetties, a pair of long jetties with a length of 800 m and 860 m, have been constructed at the Pranburi River inlet, located on the western coast of the Gulf of Thailand since 1999 to stabilize the river mouth. The purposes of this study were to evaluate the responses of shoreline due to the construction of Pranburi Jetties, and the accuracy of the One-Line model (OLM) on predicting the shoreline change due to construction. Based on the shoreline positions retrieving from aerial photographs and satellite imagery during 1967-2018, the difference in shoreline evolution before and after the construction of the jetties was evaluated using ArcGIS and Digital Shoreline Analysis System. The predicted shorelines using the One-Line model were compared with the image-analyzed shorelines for evaluating the accuracy of the model. The results indicated that the construction of Pranburi Jetties had caused the shoreline accretion at the vicinity of the jetties with the maximum accretion of up to 300 m in 2018. The land growth of 16.2 and 9 ha took place at the northern and southern coasts, respectively. The percentage of errors between the predicted and the image-analyzed shoreline varied from 2 to 13,000 percent with an average of 250 percent. Misprediction in shoreline change using a numerical model caused unnecessary construction of three detached breakwaters at the northern coast of the jetty
The Experimental investigation and Numerical Analysis on Horizontal Axis Wind Turbine with Winglet and Pitch Variations
No full textHAWT with three blades is often used, because it has the highest power coefficient among other turbines. The airfoil used is Clark-Y type because it has high glide ratio (coefficient lift/coefficient drag) in the application of subsonic flow. The main purpose of this study is to increase the power coefficient value obtained by the increase of lift force on each airfoil of blade compiler, and to fix the wind turbine performance. One of the variations added is the addition of winglets on the tip of the blade. The method employed is laboratory scaled experiment by using Wind Tunnel. Theoretically, this study also applied Blade Element Momentum (BEM) as the calculation of each segment on airfoil, and the simulation was done by using Computational Fluid Dynamic (CFD), in order to find out the characteristics of flow passing by the rotor. The advantage of using winglets is, fostering the condition of starting wind turbine rotor on small Tip Speed Ratio (TSR) condition by varying the pitch angle on the blade. The addition of pitch variation gives an advantage that it can maximize the wind speed towards the angle of attack to airfoil, hence it increases the aerodynamic effect on the rotor
Logistic Regression Analysis of Factors Affecting Travel Mode Choice for Disaster Evacuation
Get PDFThe relationships were analyzed among the factors affecting the travel mode choice between government vehicles and private vehicles used for the evacuation of people in areas experiencing floods and landslides. The relationships were developed using a utility function to predict the probability and proportion for selection of the travel mode in future evacuations based on binary logistic regression. Three models were developed using different analytical factors based on the survey data of a sample group of people in the Mae Pong watershed, Laplae district, Uttaradit province, Thailand. It was found that the factors affecting the selection of travel mode in all three models consisted of sex, household size, families with young members, education, car ownership, experienced a disaster, recognition of shelter location, safety of evacuees while evacuating, reaching the destination quickly, convenience of vehicle access, proportional family management for evacuation, ease of the evacuation procedures of mode, and difference between travel time and walking time to the assembly point. Models 1, 2, and 3 could predict with accuracies of 78.40, 73.46, and 75.30 percent, respectively
Experimental Characterization of Maize Cob and Stalk Based Pellets for Energy Use
Get PDFThe quest for alternative energy sources is gradually shifting from natural fossil fuel to alternative bio-resources especially agricultural waste products due to their reduced pollution risk and sustainability. This study seeks to investigate the suitability of plant residue pellets to produce biomass. The plant residues investigated include corn cob and corn stalk. Three samples produced include 100% granulated corn cob residues, 100% granulated stalks and a composite of 50:50% granulated corn cobs and stalk residues. The mixed residues were pelletized using cassava starch as a binder. The pellets were experimentally analyzed using ultimate, proximate and calorimetry analyses. Among three sets of maize residue pellets investigated, the result of the cob-stalk 50:50% combination show that it has 0.64% nitrogen, 48.57% carbon, 0.38% Sulphur, 6.22% hydrogen, 55.81% oxygen, 3.25% moisture content, 2.20% ash content, 80.0% volatile matter, 17.80% fixed carbon percentage, HHV of 32.9 kJ/kg, an average CO2 value of 563±50 PPM, an average CO value of 100±50 PPM, an average value of 69±4% relative humidity and an average temperature of 27.5±0.5%. The study reiterates that corn stalk is a good bio-fuel and should be encouraged to address the current energy shortfalls in the country