Journal of Engineering and Technological Sciences
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Optimization and Modeling of Ammonia Removal from Aqueous Solutions by Using Adsorption on Single-walled Carbon Nanotubes
Get PDFDue to the health effects of ammonia as an environmental pollutant, such as its odor, corrosion, algae phenomenon, etc., a method should be adopted to remove it from wastewater. In this study, removal of ammonia from hypothetical wastewater was investigated using adsorption on SWCNTs. The Design-Expert software was used to design the experiments and optimize the parameters that are effective in the adsorption performance of carbon nanotubes (CNTs), such as contact time, adsorbent dosage, pH, temperature, and ammonia concentration. The results revealed that the maximum adsorption with a performance of 90% was attained at a pH of 9.5. In addition, the adsorption performance was enhanced by increasing adsorption time and adsorbent dosage. Furthermore, increasing the temperature and the adsorbate quantity led to a decrease in the adsorption performance
Blending Lime with Sugarcane Bagasse Ash for Stabilizing Expansive Clay Soils in Subgrade
Get PDFExpansive soils constitute one of the most frequently encountered and challenging soils to geotechnical engineers. This study assessed the possibility of utilizing sugarcane bagasse ash (SCBA) by partially replacing slaked lime to stabilize expansive clay soils. The soil samples were picked from Muduuma area, Mpigi district, Central Uganda. Experimental tests of linear shrinkage (LS), plasticity index (PI), and California Bearing Ratio (CBR) were conducted on both unstabilized soil and SCBA-lime treated samples. The SCBA-lime mixture was prepared by partially replacing 5% lime with SCBA at 2, 4, 6, 8, and 10% by weight. Hence, SCBA was used in proportions of 0.1, 0.2, 0.3, 0.4, and 0.5% by dry weight of the soil. The addition of lime greatly lowered the PI and LS, which later increased with the addition of the SCBA. The maximum dry density was generally lowered with the addition of lime and SCBA, from 1.87 g/cm3 to 1.58%. The CBR increased with SCBA-lime addition from 12% for unstabilized soil up to 48% at 6% SCBA replacement. The optimum lime replacement was established as 6% SCBA lime replacement based on CBR criteria. At the 6% optimum, the optimum moisture content (OMC) was 1.7 Mg/m3, LS was 10%, and PI was 20%. This study demonstrated the potentiality of SCBA as a novel construction material, specifically by partially reducing the usage of the unsustainable, non-environmentally friendly lime. It is also expected to enable using currently unsuitable clays from the region
Development of Single-Phase Microbial Cementation Method and to Investigate its Efficacy on Bearing Capacity, UCS, and Permeability of Sandy Soils
Get PDFMicrobially induced calcite precipitation (MICP) is a method based on collaborative knowledge of microbiology, chemistry and geotechnical engineering. The objective of this study was to investigate the increase of the bearing capacity and the unconfined compressive strength (UCS) as well as the reduction of the permeability of sandy soil using MICP. Experiments were carried out using Bacillus Pasteurii, on three different types of sand. The admixture of bacterial culture and cementation (BCC) solution all-in-one with sand by single-phase injection was applied to induce cementation. Three samples of the selected sand were treated with varied concentrations of BCC solution, ranging from 0.05 to 0.2 L/kg, with a curing period of 3, 7 and 14 days. The test results indicated an enhancement of 55% in UCS for sand treated with a BCC content of 0.05 to 0.2 L/Kg and a reduction of 40% in permeability for untreated sand with an effective diameter of 0.5 mm treated with 0.2 L/kg of BCC solution after 14 days of curing. The results of a plate load test (PLT) on MICP treated sand showed an increase in the ultimate bearing capacity (qu) by about 2.95 to 5.8 times and a 1.7 to 3.31-fold reduction in settlement corresponding to the same load applied on untreated footing. Further investigation of the size and shape of the bearing plate on bearing capacity and settlement was carried out through a plate load test. The higher and more favorable results shown by a rectangular plate compared to a circular plate indicate that the first is preferable
Performance Evaluation of Homogeneous Charge Compression Ignition Combustion Engine - A Review
Get PDFThe development of HCCI combustion technology has been drawing a great deal of attention from researchers. This survey explains ongoing research methodologies and results. HCCI combustion, other than conventional combustion, is purely based on chemical kinetics. At present the automobile sector faces the problem of emissions and needs to develop clean technologies. However, HCCI operation still has issues such as ignition control, combustion phasing control, operating range control, cold start, and UHC (unburned hydrocarbon) and CO (carbon monoxide) emissions. The challenge is to overcome these problems without compromising other engine parameters and performance. For HCCI, the mixture preparation is especially important, while the compression ratio, IVC (inlet valve closure) timing, inlet pressure, inlet temperature and EGR play a very prominent role in controlling it. This paper will go through a detailed discussion of all the above conditions
A Proposal of Seismic Index for Existing Buildings in Indonesia using Pushover Analysis
Get PDFIndonesia has often suffered major earthquake damage over the past 50 years. There are thousands of buildings in earthquake-prone regions that still need seismic evaluation and rehabilitation. One method of evaluating the seismic performance of an existing building is by assessing it using the Japanese seismic index for structures. A basic seismic index can be calculated based on the strength and ductility criteria. The strength and ductility performance of a structure can be obtained by pushing a building until it reaches its maximum deformation capacity. This paper describes a proposal to obtain a basic seismic index using pushover analysis. Its adjustment to determine a seismic demand index by considering seismic hazard in Indonesia was carried out using the capacity spectrum method. Two existing buildings in Indonesia were evaluated. The evaluation result indicated that both buildings were in safe condition. The proposal of the seismic index method can be useful in determining the performance index of existing structures. The ductility index can also be used to estimate the response modification factor of a structure
Atomistic Investigation on the Role of Temperature and Pressure in Diffusion Welding of Al-Ni
Get PDFThis paper presents an investigation of diffusion welding of aluminum and nickel at the atomic scale by utilizing molecular dynamics simulation. By employing several temperature and pressure values, the significant influence of the two could be obtained and thus the optimum parameter values could be obtained. The results showed that the bonding mechanism is mostly promoted by Al, in which the deformation and defects are involved. The results on both the mechanical properties and the evolution of the diffusion configuration showed that temperature has more impact compared to pressure. It was indicated that by raising the temperature to 700 K with the lowest pressure (50 MPa), both the mechanical properties and the evolution of the diffusion configuration showed a relatively significant difference. On the one hand, the deformation that occurs during welding, which is mostly caused by raising the temperature, obviously promotes joining and therefore more joining depth can be achieved, although it results in a curved diffusion zone at the interface. On the other hand, it also leads to a lower ultimate tensile strength. During the tensile test, raising the temperature also led to focusing the deformation in the diffusion zone, while a lower temperature resulted in a wider area of deformation
Long-Term Performance of a Pilot Scale Combined Chemical Precipitation-Ultrafiltration Technique for Waste Brine Regeneration at Chevron Steam Flooding Plant
Get PDFIn this work, chemical precipitation-ultrafiltration (UF) was applied for waste brine regeneration from a steam flooding plant at Duri Field, Chevron. A mixture of sodium hydroxide and sodium carbonate solution was used as chemical agent. A polypropylene (PP) UF membrane was used to remove precipitate formed in the chemical precipitation. It was found that the combined process could be used to regenerate waste brine, removing up to 100% (±0.1) of calcium and up to 99.6% (±0.3) of magnesium. High hardness removal was achieved when the chemical dosage was 1.3 to 1.7 mole of chemical/mole of hardness. Rapid permeability decline was observed in the UF membrane due to the high turbidity and TSS values of the chemically treated waste brine. Backwash with an acid solution could recover the UF membrane's permeability effectively. However, pH adjustment is needed due to the high pH value of the UF permeate (up to ~12)
Lessons Learned from Rapid Development of CPAP Ventilator Vent-I during Covid-19 Pandemic in Indonesia
Get PDFHere, lessons learned during the development of the CPAP ventilator 'Vent-I', aimed to help COVID-19 patients with breathing difficulties, are presented. Within only weeks, the Vent-I was developed, complying with functionality, safety and reliability requirements and passing the clinical trial. It was then distributed to hospitals all over Indonesia. Two billion rupiahs were raised through crowdfunding within one week. When the project was officially closed, more than one thousand Vent-I devices had been distributed and more than twelve and a half billion rupiahs had been raised. Currently, commercialization and mass production of the device have been started. From this project several lessons can be learned. First and foremost, the spirit of gotong royong"“ sincere collaboration within the community to help each other "“ is still firmly rooted within the people and the society of Indonesia. Noble values, i.e. sincerity, sensitivity and concern about the needs of the community, willingness to serve voluntarily and public trust, made the team dare to try and face failure. The spirit of social entrepreneurship, willingness to listen to the user and collaboration with the relevant authority can accelerate development process. The availability of knowledge and skills that constitute an innovation ecosystem in Bandung, supported by business, social institutions and government, was also a key success factor.