Journal of Engineering and Technological Sciences
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Kinetics on Organic Removal by Aerobic Granular Sludge in Bubbled Airlift Continuous Reactor
Get PDFAn assessment of aerobic granular sludge (AGS) in a bubbled airlift continuous reactor (BACR) was done to determine the AGS growth kinetics in the continuous reactor and the impact of varied hydraulic retention time (HRT) against the AGS structure. Sodium acetate was used as the sole carbon source with a 100:20 ratio of COD/N synthetic water. The system was operated at five variations of HRT, i.e. 12, 10, 8, 6, and 4 hours, with organic loading rate (OLR) ranging from 1.6 to 4.8 g COD/day in the BACR. Organic removal decreased from 73% to 52%, along with the increment of OLR, while HRT decreased from 12 hours to 4 hours. The kinetics of organic removal in the BACR were examined to get a better understanding of organic removal trends by AGS in a BACR. The models used for biomass growth analysis were the Monod, Contois, Grau second-order, and Stover-Kincannon kinetic models. This study showed that the best suited models for organic removal in BACR were the Grau second-order kinetic model with an a value of 0.1382 and a b value of 1.0776, and the Stover-Kincannon kinetic model with an Rmax of 5.8 g COD/L.day and a KB of 6.24 g COD/L.day
Effect of Polystyrene Latex Addition on Size and Pore Volume of Porous Calcium Oxide Particles Prepared by Spray-Pyrolysis Method and Its Ability for SO2 Retention
Get PDFIn this study, the effects of polystyrene (PS) latex addition on the particle morphology and the pore content of calcium oxide (CaO) were investigated. The CaO particles were prepared using an ultrasonic nebulizer-assisted spray-pyrolysis method with variation of the PS/Ca(NO3)2·4H2O mass ratio in the precursor. Good crystallinity of CaO was obtained at 825°C of synthesis temperature under 2 l/min of nitrogen gas flow, which was confirmed by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). According to scanning electron microscope (SEM) characterization, the CaO particles synthesized with 0 and 25 wt% PS addition had an almost spherical shape with an average size of 1.58 and 1.48 µm, respectively. In addition, macropores were formed in the CaO particles prepared with 25 wt% PS addition that had an average pore diameter of 583.26 nm. Meanwhile, the CaO particles prepared with 75 wt% PS addition had a random shape and an average size of 1.41 µm. The mesopore content was investigated by Barret-Joyner-Halenda (BJH) analysis, which showed improvement of the pore size from 3.45 nm to 5.42 nm for 0 and 25 wt% PS addition, respectively, which is proportional to the pore volume, pore surface area, and the capacity of SO2 retention
Study on the Performance of Ball Mill with Liner Structure based on DEM
Get PDFThis study used the discrete element method (DEM), which is effective and popular for solving the problem of granular systems simulating the motion of particles in a ball mill in different structural forms and at different rotational speeds. Firstly, simulations of five kinds of lifters (triangular, trapezoidal, rectangular, ladder and hemispherical) were set up. The results were as follows: when the rectangular lifter was selected as mill liner, the ball mill efficiency was significantly high. The breaking performance of the hemispherical lifter and the ladder lifter was poor, because the main pattern of motion was grinding rather than impact breakage. Secondly, the effects of the height"“width ratio of the rectangular lifter, the height of the lifter and the number of lifters on the working efficiency of the ball mill were studied. It was found that a number of rectangular lifters of 12 and a height-width ratio of 3:1 produced the best results. The best height of the rectangular lifter was about 13 mm. Lastly, displacement, stress and deformation were analyzed using DEM coupled with a finite element method (FEM). The purpose was to design the geometrical lifter structure and to improve the performance of the ball mill
Properties and Performance of Gas Diffusion Layer PEMFC Derived from Coconut Coir
Get PDFIn this work, carbon composite papers (CCP) were successfully produced by mixing 80 wt% carbon derived from coconut coir and 20 wt% binder (ethylene vinyl acetate and polyethylene glycol). The CCPs were prepared with two different forms of carbon material, i.e. powder (particle size: ± 74 µm) and fiber (length: ± 2 mm, diameter: 100-500 µm). Two types of papers were developed based on their composition. The first type, called CCP-1, was made from carbon in powder form (80 wt%), while the second one, CCP-2, was based on a combination of fiber (70 wt%) and powder (10 wt%). The influence of the carbon form on CCP properties were investigated, including electrical conductivity, porosity, hydrophobicity, microstructure, and its performance as a gas diffusion layer (GDL) in a stack of proton exchange membrane fuel cell (PEMFC) system. Based on the results, CCP-1 showed a slightly better fuel cell performance than CCP-2, which was also confirmed by its lower porosity, electrical conductivity, and water contact angle. The effect of carbon composite paper's properties, including its morphology and performance, are disscused in this paper in detail and compared with a commercially based GDL material (TGP-H-120)
Land Cover and Climate Change Impact on River Discharge: Case Study of Upper Citarum River Basin
Get PDFThe Upper Citarum River Basin is the main catchment area of the Saguling Dam, the most upstream of three cascade dams in the Citarum River Basin. During the last 30 years, rapid economic development has led to an increase of water extraction and land conversion from green area to developed area. Also, evidence of climate change can clearly be seen from the climatological records of a number of climatology stations in this basin over the last few decades. In this study, the effect of anthropogenic and climate change in the Upper Citarum River Basin river discharge was simulated using the Sacramento Catchment Model. Historical river discharge, rainfall, climatology, and land cover from 1995 to 2009 were used for model calibration and verification. The multi-model mean monthly rainfall and the temperature projection taken from Coupled Model Intercomparison Project 5 (CMIP5) for the RCP6 and RCP8.5 climate change scenarios were statistically downscaled and used as input for a simulation of future river discharge from 2030 to 2050. The result showed that the combination of anthropogenic and climate change may result in a significant decrease of low flow in the Upper Citarum River Basin. This study underlines the importance of land cover and climate change factors for future infrastructure planning and management in the Upper Citarum River Basin
The Integration of MAFMA and AHP Methods for Analysis and Risk Mitigation of Pasteurized Milk Production
Get PDFRisk and uncertainty management is an important task in industry. Risks in raw materials such as livestock products may occur from the feed. The production process is also exposed to risks, which may be caused by controllable variables. In final products, uncontrollable actions may also pose risks. This research aimed to figure out the risks and their causes in the production process of milk and to discover applicable mitigation strategies. The methods used in this study were the Multi-Attribute Failure Mode Analysis (MAFMA) method to find the causes and Analytic Hierarchy Process (AHP) to discover mitigation strategies. The results were in the form of risks in the production process caused by: 1) raw materials, 2) the production process, 3) human resources, and 4) machinery and equipment. The highest risk in the production process is posed by undetected damage to machinery and contamination during the production process. However, both are rooted in human error: poorly trained workers, omission of checking or testing, and poor supervision of the process. Mitigation strategies, i.e. standardization and supervision of the raw materials, production process, and final product, were implemented to reduce the potential risks. In the implementation of these strategies, worker participation, either as controller or as supervisor, is very important
Numerical Simulation on the Influence of Bridge Construction on River Flood Control in a Bottleneck Reach
Get PDFBottleneck reach regions with narrow and deep cross sections prevent sediment transport and weaken flood control capacity. In addition, bridge constructions can exacerbate the risk of flooding in these areas. In this study, the Longhai Railway Extension Project at the Xianyang reach of the Weihe River in China was selected as a typical object. A horizontal 2-D numerical model was used to assess the effects of three engineering plans on flood discharge capacity under three flood frequencies. Plan 1 was designed to include building a new bridge, demolishing the three original bridges and dredging a single section of the channel. Plan 2 was the same as Plan 1, except for the compound sections. Plan 3 was designed with the four bridges coexisting and no dredging projects carried out. The results indicated that Plan 3 will increase the water level by 0.2-0.3 m in the upstream reach. The cross-sectional area was approximately 370 m2 larger under Plan 1 than under Plan 2. Water levels of 300-, 100-, and 5-year flooding around the bridge were reduced by 0.9, 0.9, and 0.6 m, respectively. To improve flood control capacity, an effective dredging project must be executed to widen the river and reduce the water stage in the bottleneck reach where the bridge is constructed
Drilling Strategy for Thick Carbon Fiber Reinforced Polymer Composites (CFRP): A Preliminary Assessment
Get PDFCarbon fiber reinforced polymer or CFRP composites are the epitome of high-performance materials in lightweight design. However, their machinability can be problematic due to non-homogenous and anisotropic material properties. This preliminary assessment emphasizes drilling strategy by using mechanical drilling and laser machining on 25.4 mm thick CFRP, which has not been investigated so far. In mechanical drilling, three drilling strategies were applied with the same parameters in order to assess the feasibility of drilling thick CFRP. The laser machining experiments were conducted to identify the potential of fiber laser machines to cut thick CFRP due to their superior laser beam quality. The results showed that choosing the appropriate drilling strategy in mechanical drilling is essential for reducing damage when drilling thick CFRP. Significant damage occurred in all experiments. The results are useful to define the relationships between machining parameters related to mechanical/laser drilling and hole/cut quality