Journal of Engineering and Technological Sciences
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Developing a Plastic Waste Management Program: From River Basins to Urban Beaches (Case Study)
Get PDFSolid waste accumulation in coastal environments has been a growing concern. In the coastal megacity of Recife, Pernambuco state, Brazil, plastic waste issues currently exist both at the ocean scale and river basin scale. The city is known as the 'Brazilian Venice' thanks to the Capibaribe River, which crosses many neighborhoods, running in a west-east direction into the Atlantic Ocean. This paper provides the initial basis to develop a Plastic Waste Management Program proposal for implementation in the city of Recife, given the lack of resolutions that have looked at plastic waste management through integrated water environment scales (from river basin to ocean). The methodology used included articulation and documental collection from four main public agencies from the state/city and stakeholders. The results showed its relevance for better plastic waste management in Recife, considering an integrated water environment on a river basin-to-ocean scale by using the recognized major connected water environments (Capibaribe river and Boa Viagem beach). Similar integrated program proposals could be made for other coastal areas, enabling not only the identification of fragilities but also the exchange of information regarding the theme
The Distribution of Microplastics in Beach Sand in Tien Giang Province and Vung Tau City, Vietnam
Get PDFMicroplastics threaten the ecosystem because of undesirable properties such as non-biodegradability, easy-to-absorb persistant organic compounds, etc. They are found worldwide in marine, fresh water and beach sand environments. In this study, microplastics in beach sand samples from two sites in Tien Giang province and two sites in Vung Tau city were investigated. The results showed that the microplastics amount was 0 to 295 pieces/kg dry sand and they mainly distributed near estuarine areas. Microplastics were more prevalent at bathing sites than non-bathing sites. In Tien Giang fragments were the most dominant among the three types of shapes (fragments, fibers, granules) at 60.2%. In Vung Tau granules were most prevalent at 71.7%. The composition of the plastics was confirmed by Fourier-transform infrared spectroscopy. It was revealed that PE, PP and PS were the main types of plastics found in the sampling sites.
Comparison of Several Processing Methods in Preserving the Flavor Properties of Andaliman (Zanthoxylum acanthopodium DC.) Fruit
Get PDFAndaliman (Zanthoxylum acanthopodium DC.) is a plant endemic to North Sumatra. Its fruit has a very specific citrus-like aroma, gives a tingling sensation and is commonly used for seasoning in Bataknese traditional cuisine. To extend the shelf life and preserve the quality of andaliman fruit, post-harvest handling is needed. Seven drying methods were applied and compared, i.e. sun, air, fluidized bed, oven, far infrared, freeze, and spray drying. Considering the physicochemical and sensory properties and efficiency, oven drying was selected for further study. The optimum condition for drying was temperature at 54 °C for 8 h resulting in 0.67 desirability level based on the response surface method (RSM). Spray drying encapsulation of andaliman fruit extract was performed at an inlet temperature of 150 °C with an extract to carrier ratio of 1:8. Maltodextrin (MD) and gum arabic (GA) with a ratio of 3:2 was chosen as the carrier agent. The quantitative descriptive analysis (QDA) result showed that the encapsulated andaliman powder had a flavor that resembled fresh andaliman with a more pronounced taste, a citrus-like trigeminal sensation, and a sour floral citrusy aroma
Bisphenol A Removal by Graphene Oxide Applied in Different Processes
Get PDFBisphenol A (BPA) is a commonly used plasticizer incorporated into the parent plastics during manufacturing. It is classified as an emerging contaminant that is continually detected in aquatic environments and is listed as an endocrine disrupting chemical confirmed to be associated with cardiovascular disease and reproductive disorder. The hazardous aspects of BPA require the development of innovative methods for its degradation. Among these techniques, adsorption and electrochemical degradation are considered to be particularly attractive due to their high efficiency, versatility and environmental friendliness, since they do not require any other chemicals. The use of graphene oxide (GO) was investigated as an adsorbent and as a particle electrode for the removal of BPA from aqueous solutions. The adsorptive behaviors of GO toward BPA were investigated in batch mode under darkness, visible light and UV light conditions. GO was used as particle electrode in a three-dimensional electro-oxidation (3D-EO) process established by an Ru/TiO2 anode and the effects of current density values ranging from 10 to 50 mA/cm2 were investigated. The obtained results revealed that the 3D electrochemical degradation process achieved a higher BPA removal efficiency than adsorption, showing that 3D-EO with a graphene oxide particle electrode may significantly improve BPA removal efficiency
Simulation of Convective Heat Transfer in 3D Forward Facing Step Using Various Turbulence Models
Get PDFIn this work, a modified solver from the OpenFOAM 4.1 software was used to study the fluid flow and heat transfer characteristics over a forward facing step (FFS) considering various turbulence models, viz., k-ε, k-ω, k-ω SST and v2-f. Numerical computations were performed using a newly developed transient solver, pisoTempFoam. Modeling and meshing of the geometry and setting of the boundary conditions were done with OpenFOAM. The bottom (upstream, step and downstream) walls were heated at a constant temperature of 350K, while the fluid inlet temperature was 298K. The simulation results were compared with those available in the literature. Variation of skin friction coefficient (Cf), coefficient of pressure (Cp), and Nusselt number (Nu) for different Reynolds numbers (Re), contraction ratios (CR) and different fluids are presented. This article also presents information about recirculation bubbles in the upstream and downstream regions of the FFS. The results show that the combined effect of turbulence models and parameters, such as CR, Re and Pr, change the flow and heat transfer characteristics of the FFS. The present CFD simulation plays a pivotal role in the analysis of flow over airfoils at a large angle of attack in heat exchangers and pipes whose area suddenly changes
Identification of Contact Stiffness between Brake Disc and Brake Pads Using Modal Frequency Analysis
Get PDFThe contact stiffness between brake disc and brake pads is a vital parameter that affects brake NVH performance through increasing the system stiffness and modal frequencies. In order to establish accurate contact behavior between brake parts for further research on precise modeling of disc brakes, a method of identifying the normal contact stiffness of a floating caliper disc brake was developed in this study based on modal frequency testing and finite element analysis. The results showed that contact stiffness increases with brake pressure due to compression of the friction material and increases with the disc mode order at lower-order modes but almost stays invariant at higher-order ones due to contact area variation
Evaluation of Bio-Corrosion on Carbon Steel by Bacillus Megaterium in Biodiesel and Diesel Oil Mixture
Get PDFBiodiesel can act as carbon source for bacterial metabolisms, leading to corrosion of carbon steel. In this study, the corrosion of carbon steel by biodiesel blends (B15, B20, B30) was observed in the presence of Bacillus megaterium. The effect of biodiesel concentration on microorganism-induced corrosion was investigated by electrochemical impedance spectroscope (EIS), scanning electron microscope (SEM) and digital microscope. The results showed that under various biodiesel concentrations, Bacillus megaterium can grow and form biofilm on carbon steel. Based on the impedance analysis, their presence can increase the corrosion rate and cause pitting corrosion because the biofilm can change the electrochemical reactions in the metal or the interface solution and the kinetics of the anodic cathodic reactions. Also, Bacillus megaterium produces acid metabolites and can oxidize iron. Besides being influenced by Bacillus megaterium activities, the pitting formed on carbon steel depends on the biodiesel concentration. The results showed a great deal of shallow pit formation in B30, exacerbating the severity of metal roughness
Seismic Performance of RC Hollow Rectangular Bridge Piers Retrofitted by Concrete Jacketing Considering the Initial Load and Interface Slip
Get PDFIn design practice, the assumptions that are used in retrofitting concrete structural elements often ignore the initial load and the interface slip on the contact surfaces between the old and the new concrete. The concrete structural elements that are loaded by the existing gravity load cause initial strain on the existing cross-section before jacketing is applied, while the interface does not act in a fully composite manner. In this study, a seismic performance evaluation using pushover analysis was performed of a damaged reinforced concrete bridge pier retrofitted with concrete jacketing, where the plastic hinge of the retrofitted elements was modeled by considering both parameters. The results showed that concrete jacketing could increase the capacity of the bridge structure. It was also found from the numerical result that the performance level of the bridge considering the initial load compared to the monolithic approach gave the same result since the initial load did not significantly affect the cross-sectional ultimate capacity. The difference between the ultimate capacity values computed by the two models was less than 7%. It was also shown that the interface slip had a significant effect with a slip coefficient smaller than 0.5
Self-Potential Method to Assess Embankment Stability: A Study related to the Sidoarjo Mud Flow
Get PDFThe stability of an embankment is generally influenced by a number of factors, such as deformation, fractures, overtopping, seepage, etc. Fractures and seepage are commonly found in the LUSI (Sidoarjo mud flow) embankment. In this study, analysis of self-potential (SP) data was applied to identify fractures and seepage in the LUSI embankment. Noise-Assisted Multivariate Empirical Mode Decomposition (NA-MEMD) and Continuous Wavelet Transform (CWT) were applied to determine the location of seepage and fractures in the subsurface based on SP data. The results were correlated with the 2D direct current resistivity (DCR) method, which showed that both methods worked well and were compatible in detecting and localizing fracture and seepage in the LUSI embankment
Low-Cost and Portable Sound Reduction Box: Innovation for Acoustic Material Performance Measurement
Get PDFA sound reduction index (RIc) is a laboratory measurement of the sound insulating properties of a material or building element, commonly conducted using a reverberation chamber and an anechoic chamber (SIC), which requires high expenses. This study aimed to perform RIc analysis using a sound reduction box (SRB) to assess the accuracy and precision of the associated result compared to an SIC. The SRB is a miniature reverberation chamber innovation that is owned by the Center for Research and Development of Quality and Environmental Laboratory (P3KLL). The anechoic chamber is substituted by open space as free-field environment. The methods used in this study are based on ISO 15186-1 and ISO 717-1. Measurement was executed using a sound intensity analyzer and data interpretation was done by employing statistical analysis. The types of insulating materials tested were wood boards made of Shorea sp., Swietenia sp. and Dryobalanops sp. with a thickness of 2 cm and 4 cm. Test material measurement was done using the same measuring instruments, sound generators, sound amplifiers, and personnel. The results show that the RIc values were almost the same for both methods (SIC and SRB). When the weighted sound reduction index (Rw) rating calculated from the RIc was compared between the SIC and the SRB, the results were not statistically different. It is interesting that an SRB can be developed in the future as an alternative device for acoustic materials testing