Journal of Engineering and Technological Sciences
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Effect of Sonication Frequency and Power Intensity on the Disruption of Algal Cells: Under Vacuum and Non-Vacuum Conditions
Full text linkThe presence of algae caused by anthropogenic eutrophication in water has become a severe environmental issue. Various treatment options for algae removal have been developed, such as filtration, coagulation, sedimentation, flotation, algicides, ozone, and photolysis. However, these technologies are complex, expensive, consume considerable amounts of various chemicals, and may cause further pollution (i.e., by-product formation). Ultrasonic exposure is an alternative method for removing algae from water that is environmentally friendly (i.e., no addition of chemicals) and almost unaffected by any turbidity in the water. In this study, process optimization of ultrasonication (e.g., by adjusting frequency, power intensity, and exposure time) for the removal of alga was tested under vacuum and non-vacuum conditions. Experiments were conducted on a batch of algae solution in a clear glass tube ultrasonicated by a 20 kHz transducer for 180 minutes. The tube was depressurized up to -67 N/m2 in a depressurizing chamber. The data was collected at transducer depths of 0.06, 0.13, and 0.19 m. It was concluded that the optimum condition (i.e., 92% algal cell disruption) was achieved when the power intensity was 7 kWh/m3, under vacuum conditions, at a frequency of 20 kHz and 180 minutes of exposure time. Higher power intensity gave higher energy for cell disruption, moreover by depressurizing the air above the algae solution, the lysis effect for algae reduction increased from 20% to 70% compared to the non-depressurized system due to higher cavitation bubble production. In addition, the depth of the transducer was another factor that could increase the lysis of the algae water. Therefore, this technology has future potential application for algae removal from water
A Review on Zeolite Application for Aromatic Production from Non-Petroleum Carbon-Based Resources
Full text linkThe application of zeolite catalyst has been expanded to support on-purpose sustainable technology. This review focused on zeolite application to produce aromatic compounds from non-petroleum carbon-based resources, including methanol, CO2, CO, and biomass. For COx resources, the two main routes for producing aromatics products are discussed, i.e., the olefinic and the oxygenates-mediated route. Moreover, several improvement strategies for enhancing catalytic performance are also discussed, i.e., the addition of metal components, tuning the metal and zeolite structure, and modifying the reaction process. Finally, prospects for future development are formulated
Rapid Flood Mapping Using Statistical Sampling Threshold Based on Sentinel-1 Imagery in the Barito Watershed, South Kalimantan Province, Indonesia
Full text linkFlood disasters occur frequently in Indonesia and can cause property damage and even death. This research aimed to provide rapid flood mapping based on remote sensing data by using a cloud platform. In this study, the Google Earth Engine cloud platform was used to quickly detect major floods in the Barito watershed in South Kalimantan province, Indonesia. The data used in this study were Sentinel-1 images before and after the flood event, and surface reflectance of Sentinel-2 images available on the Google Earth Engine platform. Flooding is detected using the threshold method. In this study, we determined the threshold using the Otsu method and statistical sampling thresholds (SST). Four SST scenarios were used in this study, combining the mean and standard deviation of the difference backscatter of Sentinel-1 images. The results of this study showed that the second SST scenario could classify floods with the highest accuracy of 73.2%. The inundation area determined by this method was 4,504.33 km2. The first, third and fourth SST scenarios and the Otsu method could reduce the flood load with an overall accuracy of 48.37%, 43.79%, 55.5% and 68.63%, respectively. The SST scenario is considered to be a reasonably good method for rapid flood detection using Sentinel-1 satellite imagery. This rapid detection method can be applied to other areas to detect flooding. This information can be quickly produced to help stakeholders determine appropriate flood management strategies
Reducing Numerical Dispersion with High-Order Finite Difference to Increase Seismic Wave Energy: -
Full text linkThe numerical dispersion of 2D acoustic wave modeling has become an interesting subject in wave modeling in producing better subsurface images. Numerical dispersion is often caused by error accumulation with increased grid size in wave modeling. Wave modeling with high-order finite differences was carried out to reduce the numerical error. This study focused on variations in the numerical order to suppress the dispersion due to numerical errors. The wave equation used in modeling was discretized to higher orders for the spatial term, while the time term was discretized up to the second order, with every layer unabsorbed. The results showed that high-order FD was effective in reducing numerical dispersion. Thus, subsurface layers could be distinguished and observed clearly. However, from the modeling results, the wave energy decreased with increasing distance, so the layer interfaces were unclear. To increase the wave energy, we propose a new source in modeling. Furthermore, to reduce the computational time we propose a proportional grid after numerical dispersion has disappeared. This method can effectively increase the energy of reflected and transmitted waves at a certain depth. The results also showed that the computational time of high-order FD is relatively low, so this method can be used in solving dispersion problems
Photocatalytic Simulation of Phenol Waste Degradation Using Titanium Dioxide (TiO2) P25-Based Photocatalysts
Full text linkPhenol waste treatment is vital in industries such as polymer production, coal gasification, refinery, and coke production. Photocatalytic technology using semiconductor materials offers an effective and ecofriendly approach to degrade phenol. TiO2 P25 is a widely used photocatalyst, known for its cost-effectiveness, favorable optical and electronic properties, high photoactivity, and photostability. The PHOTOREAC application, a recently developed MATLAB-based software, simulates the degradation of phenol using visible light. A study that combines existing literature and research revealed that pH significantly influences photocatalytic activity, with an optimum pH of 7 for TiO2 P25-mediated phenol degradation. The recommended photocatalyst concentration ranged from 0 to 10 g/L for reactor volumes between 25 and 60 mL, and from 0 to 5 g/L for 100-mL reactors. Phenol wastewater volume and light intensity also impact degradation efficiency. Adequate oxygen supply, achieved through bubbling and mixing, is essential for the formation of radical compounds. The Ballari kinetic model proved to be the most suitable for phenol degradation with TiO2 P25. Thus, by combining PHOTOREAC simulations with experimental data, the treatment process could be optimized to achieve higher degradation efficiency and estimate the treatment time for specific waste degradation levels. This study contributes to the advancement of phenol waste treatment and the development of improved photocatalytic wastewater treatment technologies
Examining External Dose Rates in Mamuju Regency, Indonesia: A Personal Radiation Dosimetry Approach
Full text linkThis study aimed to quantify the individual external radiation exposure in Mamuju, Indonesia. A SmartRad portable personal dosimeter was utilized for this purpose, and data was collected over a period of 30 days. The findings indicate that the dose rate varies from 0.152 to 4.200 μSv/h and cumulatively ranges from 0.1 to 8.4 μSv/day based on an average measurement duration of 160 minutes. The average dose rate in areas with mineral deposits is 11.02 mSv per year. In contrast, the average effective dose in areas without radioactive mineral deposits is 2.6493 mSv per year. The annual average effective dose for individuals was measured at 6.8347 mSv. These findings imply that personal exposure to radiation among the public in Mamuju exceeds the threshold recommended by the International Commission of Radiological Protection
Modal Transformation based Fault Location in Radial Distribution Network
Full text linkThis paper introduces the technique of fault distance estimation based on modal transformation and signal processing. The recorded faulted phase currents are applied to the Karrenbauer model transformation and these model component currents are decomposed into detail coefficients by the use of Daubechies wavelet, db6. The fault recorder installed at the terminal of the feeder records different time delays between the modal components. In order to find fault distance, the time delay values and modal components velocity are used in traveling wave theory. This paper compares two different conditions: the first condition does not use a modal transformation and the second condition uses a modal transformation. When using modal transformation conditions, three different coefficient levels (detail coefficient level 1 (D1); the combination of detail coefficient level 1+2 (D1+2) and the combination of detail coefficient level 1+2+3 (D1+2+3) ) are used to estimate the fault distance. Different fault types with different fault locations are created in MATLAB simulation
The Material Science Behind Repetitive Hammering, Solution Annealing, and Tempering on Hadfield Steel
Full text linkThe Hadfield steel used in this study contained 11 to 14% Mn and 1.1 to 1.4% C. Hadfield steel that underwent heat treatment showed insignificant differences in microstructure and hardness. On the other hand, Hadfield steel that was subjected to heat treatment combined with repetitive hammering exhibited changes in microstructure, as indicated by the presence of more and denser slip lines in accordance with an increased amount of deformation. The hardness value of the Hadfield steel also significantly increased. The slip lines discovered in the Hadfield steel that underwent solution annealing and tempering followed by repetitive hammering increased in number and appeared more compact than in the Hadfield steel without tempering. Additionally, the hardness value of the Hadfield steel with tempering was higher than that of the Hadfield steel without tempering. The strain values and thickness reduction results showed that the Hadfield steel subjected to tempering had higher strain and thickness reduction than the Hadfield steel without tempering. Higher strain and thickness reduction leads to higher hardness
Lessons Learned in Interfacial Tension Prediction Using a Mixture of Sulfonate- and Ethoxylate-based Surfactants in a Waxy Oil-brine System
Full text linkThe chemical-enhanced oil recovery (CEOR) method is applied to change reservoir rock or fluid characteristics by injecting alkaline, surfactant, and polymer or a combination of two or three of the compounds. Surfactant flooding improves oil recovery by reducing the interfacial tension between oil and water. Selecting reservoir surfactants, especially microemulsions, requires careful screening. This study predicted waxy oil system interfacial tension using surfactant mixtures at below- and above-optimum salinity. To predict the interfacial tension, microemulsion types, HLB, ideal salinity, and HLD were used. The study predicted oil-surfactant-water interfacial tension using SAE, FEO, and their mixtures. We improved the Huh equation by adding a fitting parameter, β, to accommodate the transition from type III to type II microemulsions as salinity increases. With increasing salinity, anionic surfactant’s hydrophilic-hydrophobic interactions change, affecting the values and surfactant layer thickness. This study improved hydrophilic-lipophilic deviation (HLDN) by establishing a fixed interval for nonionic surfactants. Van der Waals attraction, values and interface surfactant layer thickness are connected, reflecting the fact that lower values reduce interfacial tension better. This study also found that surfactant packing at the oil-water interface increases the order of the oil-solution ratio and the microemulsion values with polarity
