E-waste management, treatment options and the impact of heavy metal extraction from e-waste on human health: Scenario in Vietnam and other countries

Ho Chi Minh (HCM) City is the most important urban region of Vietnam, Southeast Asia. In recent times, the quantity of electronic waste (e-waste) has been growing by several thousand tonnes every year. In this research, some of the existing and developing technologies being employed for the recycling of e-waste have been reviewed. Accordingly, the paper has been divided into three sections namely, e-waste treatment technologies in Ho Chi Minh City, the effect of heavy metals on human health and the extraction of metals from e-waste using pyrolysis, hydrometallurgy, bioleaching, mechanical, and air classifier methods, respectively. The extraction of precious metals and heavy metals such as Cd, Cr, Pb, Hg, Cu, Se, and Zn from e-waste can be hazardous to human health. For example, lead causes hazards to the central and peripheral nervous systems, blood system and kidneys; copper causes liver damage; chronic exposure to cadmium ends up causing lung cancer and kidney damage, and mercury can cause brain damage. Thus, this study examines the key findings of many research and review articles published in the field of e-waste management and the health impacts of metal pollution.The authors would like to thank Van Lang University, Vietnam for funding this work. E.R. Rene expresses appreciation to IHE Delft Institute of Water Education (the Netherlands) for providing infrastructural facilities and staff time support to collaborate on this research.Peer reviewe

Experimental insight into co-combustion characteristics of oxygenated biofuels in modified DICI engine

The co-combustion of fuel has substantial advantages when compared to normal combustion and it requires very little modification. In this perspective, ethanol supplement co-combustion with biodiesel is proposed. The co-combustion characteristics were studied by manifold induction of vaporized ethanol and direct injection of waste cooking oil biodiesel. A vaporizer system was fabricated to produce vaporized ethanol in a volumetric basis (10% and 20%, respectively). It was revealed from the experiments that with co-combustion of oxygenated biofuels, the combustion advanced and peak pressure shifted to TDC. The pressure rise rate decreased with the increase of vaporized ethanol induction and the maximum rate of pressure rise reduction was noted with biodiesel-20% ethanol induction which was 4% lower than biodiesel-10% vaporized ethanol induction. On the other hand, the maximum rate of heat release rate (60.24 J/degrees CA) was seen in biodiesel with 20% ethanol induction. Furthermore, the co-combustion studies disclosed a two-stage heat release pattern (low temperature and high temperature reactions). It was observed that the increase in ethanol concentration extended low temperature region by 1 degrees crank angle and retarded high temperature region by 3 degrees crank angle

Recent developments and strategies in genome engineering and integrated fermentation approaches for biobutanol production from microalgae

© 2020 Elsevier LtdThe major hurdles causing difficulties in mechanized transportation are the depletion of fossil fuels and the high cost of alternative plant-based substrates for producing biofuels. To solve these issues, biofuels were emerged as effective alternatives to reduce pollution caused by the emission of greenhouse gases. Among biofuels, biobutanol is gaining attention as a feasible, renewable, cost-effective, alternative fuel. But the usages of conventional agricultural crops as feedstock are sensitive and controversial due to the growing concern over the availability of food worldwide. Microalgae are an excellent resource to overcome these challenges, which grows on both the sea and freshwater. Microalgae reducing their land usage with agriculture, and there is no food and fuel conflict exist. In addition, microalgae utilize inorganic carbon from the atmosphere for growth; hence they can reduce the emission levels as well as produce clean energy. Therefore, microalgae as third-generation feedstock came into practice due to their fast growth rate and higher carbohydrate content. The main focus of the present review is to discuss in detail about the major challenges faced as a feedstock, genetic engineering strategies adopted and future perspectives to improve the production of biobutanol from microalgae

Utilization of enriched hydrogen blends in the diesel engine with MgO nanoparticles for effective engine performance and emission control

The influence of hydrogen on the diesel engine has been examined in this study. In addition, the impact of MgO nanoparticles was also analysed by conducting a series of tests on samples such as Diesel (100 % diesel), DN (Diesel-50 ppm MgO), H1N (10 % Hydrogen-50 ppm MgO) and H2N (20 % Hydrogen-50 ppm MgO). Hydrogen was injected through intake manifold at the volume of 10 % and 20 %. Nanoparticles were dispersed using the ultrasonication techniques to accrue stable suspension. The experiments were conducted between 6 N-m to 24 N-m loads on a four-stroke single cylinder engine. The parameters such as brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), and heat release rate (HRR) were assessed. In addition to the performance and combustion, the environmental impact of the test blends was also analysed by examining the exhaust with a gas analyser. From the series of tests, it was evident that hydrogen enrichment in the test blends reported lower levels of emissions compared to neat diesel. The formation of the hydrocarbons (HC), nitrogen of oxides (NOx), carbon monoxide (CO), and carbon dioxide (CO2) was reduced due to the drop in the carbon atoms and enriched oxygen content in the combustion chamber. With regard to the performance, the hydrogen enriched nanoparticle blends reported peak BTE (37 %) and HRR (75 J/deg) than the other test blends. By assessing all the results, the addition of hydrogen is a potential option to reduce the environmental impact created by the fossil fuel without forfeiting the engine efficiency. © 2022 Elsevier LtdKing Saud University, KSU; Chiang Mai University, CMU: RSP-2022/23

Role of chicken fat waste and hydrogen energy ratio as the potential alternate fuel with nano-additives: Insights into resources and atmospheric remediation process

The main focus of the study was to witness the effects of chicken waste-based biodiesel blends along with constant hydrogen injection in a modified diesel engine. Furthermore, the nanoparticle multiwall carbon nanotubes (MWCNT) effects on the engine efficiency were also examined. A series of tests was conducted in the single cylinder, water cooled engine fuelled with diesel, CB100N, CB10N, CB30N, and CB50N. Throughout the entire run, constant hydrogen injection of 5 LPM has been maintained. The parameters such as brake thermal efficiency, brake specific fuel consumption, heat release rate and the emissions of different pollutants were determined for a variety of engine speeds. ASTM standards were applied to measure the viscosity, density and calorific value. From the reported findings, it was clear that the addition of the chicken waste biodiesel could be a sustainable substitute for the existing fossil fuels. Although the emission of the pollutants was dropped significantly, there was a massive drop in the BTE values. To compensate such shortage of power, the biodiesel was dispersed with MWCNT at the concentration of 80 ppm. Compared to the regular biodiesel, MWCNT inclusion increased the BTE by 14%. Further, the consumption of the fuel was also reduced marginally. Considering the pollutants, the catalytic activity of the MWCNT reduced the emissions of CO, NOx, and HC at various engine speeds. Besides, 10% reduction in NOx had been reported at lower engine speeds and was reduced to 8% at higher speed regimes. Compiling all together, increasing the concentration of the biodiesel blends obviously reduced the performance values and however, there was a great advantage in terms of the emission magnitudes irrespective of the engine operating conditions. © 2022 Elsevier Inc.King Saud University, KS

Prediction of the fuel spray characteristics in the combustion chamber with methane and TiO2 nanoparticles via numerical modelling

In this study the methane combustion was analysed with the TiO2 nanoparticles. A series of the simulation runs were performed by varying the fuel inlet velocity. However, the oxidizer and the nanoparticles spray were maintained constant for the entire run. The spray velocity varied from 100 m/s to 200 m/s with titanium dioxide (TiO2) nanoparticles. Using the series of the governing equation and modified Navier Stokes equation the model has been developed with the aid of numerical workbench. Three different domains are generated for fuel, oxidizer and nanoparticles. The velocity of the air and nanoparticles were maintained at constant levels and varying only the spray velocity of the fuel. Based on the findings, the mass fraction of both fuel and formation of the CO2 were dependent on the spray velocity. As the spray velocity increases the turbulence in the combustion chamber increases which ensures the higher mixing of both air-fuel and nanoparticles. From the procured findings 175 m/s and 200 m/s were the ideal range for better combustion efficiency compared to 100 m/s and 150 m/s. The simulation results have ascertained the role of the spray velocity on the emissions and the combustion efficiency of the engine. It is hoped that obtained results can provide directions to work on the combustion of the methane with the nanoparticles at the optimized spray velocity.2021-KYYWF-0563, RSP-2021/315; King Saud University, KSUHeilongjiang Universities [2021-KYYWF-0563]; Researchers Supporting Project, King Saud University, Riyadh, Saudi Arabia [RSP-2021/315]; Van Lang University, Vietna