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Among various bioreactors examined in anaerobic digestion and dark fermentation, UASB bioreactor has shown to be a promising alternative. However, mass transfer resistance and biomass washout have been the issues that reported as draw backs of the granular system in the literature. Another problem associated with such a system is its long start-up period as a result of biomass washout and long microbial granulation stage. In this paper, the results obtained from an UASFF bioreactor in methane (AD process) and hydrogen (DF process) production from POME, are presented to assess mass transfer of substrate into the granules and also study the role of internal packing used in the middle part of reactor in the process stability. The value of effectiveness factor, η, for AD and DF processes were calculated to be 0.96 and 0.94, respectively, indicating that there was no mass transfer resistance due to internal and/or external factors. The results showed that the packing material could retain biomass in the reactor and had outstanding contribution in the granulation enhancement. Its role as a supplementing treatment stage was more significant at low HRTs and up-flow velocities.

Purpose This study aims to consider environmental sustainability, a global challenge under the preview of sustainable development goals, highlighting the significance of knowledge economy in attaining sustainable aggregate demand behavior globally. For this purpose, 155 countries that have data available from 1995 to 2021 were selected. The purpose of selecting these countries is to test the global responsibility of the knowledge economy to attain environmental sustainability. Design/methodology/approach Results are estimated with the help of panel quantile regression. The empirical existence of aggregate demand-based environmental Kuznets curve (EKC) was tested using non-linear tests. Moreover, principal component analysis has been incorporated to construct the knowledge economy index. Findings U-shaped aggregate demand-based EKC at global level is validated. However, environmental deterioration increases with an additional escalation after US$497.945m in aggregate demand. As a determinant, the knowledge economy is reducing CO2 emissions. The knowledge economy has played a significant role in global responsibility, shifting the EKC downward and extending the CO2 reduction phase for every selected country. Further, urbanization, energy intensity, financial development and trade openness significantly deteriorate the environmental quality. Originality/value This study contains the empirical existence of aggregate demand-based EKC. The role of the knowledge economy is examined through an index which is calculated by using four pillars of the knowledge economy (technology, innovations, education and institutions). This study is based on a combined panel of all the countries for which the data was available.

Abstract The variation of properties with temperature have many practical applications in the area of chemical engineering and metallurgy, in the process of extrusion, the materials moving between a feed roll and on carrier belt. Here our intention is to explore the consequences of temperature dependent viscosity and variable thermal conductivity on flow of nanoliquid in a rotating system. Fluid between parallel plates is taken. Energy expression incorporates the exponential heat source. This analysis also explores the attributes of modified Arrhenius energy function with chemical reaction. Boundary layer problems have been computed via NDSolve approach. The obtained solutions are sketched for various estimations of embedded variables of interest. Results pointed out that both axial and transverse velocities show decaying behavior for higher rotation parameter. Thermal field boosts up with an enhancement of thermophoretic and space dependent heat source variables. Moreover the rate of mass transport decays through dimensionless activation energy.

This study searches the impact of tourism growth on emission pollutants in Cyprus (north), which is a small island in the Mediterranean and has shown significant development in hotel and casino sectors in the last two decades. Results from time-series analyses reveal that an inverted U-shaped EKC hypothesis is confirmed for Cyprus with and without tourism development. Tourism also exerts positively significant and long-term effects on the levels of carbon emissions, revealing that growth in the tourism sector causes degradation in the environment.

Abstract Liquefaction of poly-isoprene based rubber (PIR) was performed using ethanol as a solvent for the production of liquid fuel and chemicals. An autoclave batch reactor was used to perform the ethanolysis of PIR at different temperature ranges (250–375 °C), with different ethanol to PIR ratio (0.5:1 to 4:1), and at different reaction times (15–75mins). The experimental results showed that a maximum yield of 86 wt % was achieved at temperature of 325 °C, ethanol to PIR ratio 1/1, and reaction time of 30 min. This liquid oil yield is about 14% higher than the yield obtained from the pyrolysis of PIR at 500 °C and about 10% higher than the yield obtained from hydrothermal liquefaction of PIR at 375 °C. Moreover, the utilization of ethanol in the process was also incorporated and product yields were redefined. Furthermore, ethanol contributed to enhance the quality of liquid-oil, particularly in term of viscosity, acidity, and energy density. Furthermore, the FTIR analysis showed methyl and methylene were most dominating functional groups found in the liquid product and GCMS analysis identified that they were presented by alkenes, aromatics, and alkyls.

Abstract Energy conservation measures (ECM) through awareness, good housekeeping measures and demand side management are the first step that must be implemented to achieve energy savings in any building. The energy savings from the implemented ECM must be properly quantified to demonstrate its effectiveness and success. Quantifying energy savings using Multiple Linear Regression (MLR) model have been gaining popularity due to its simple approach but its inability to model and predict dynamic behavior that involves non-linearity relationships can be seen as its main drawback. Thus, the objective of this work is twofold, where the first fold is to implement an ECM program in a building and the second fold is to determine the energy saved from the ECM program using Non-Linear autoregressive with Exogenous inputs artificial neural network (NARX-ANN). The ECM program was executed at one floor of a university building. NARX-ANN was used to model the baseline energy consumption and determine the energy savings following the International Performance Measurement and Verification Protocol (IPMVP). A comparison was made between the MLR and the NARX-ANN model where the latter provides higher accuracy in statistical error compared to the MLR model. The energy savings from the awareness program determined by the NARX-ANN model was 170.84 kWh with Mean Square Error and Root Mean Square accuracy of 0.6068 and 0.7790 respectively.

Landfill gas (LFG) is essentially greenhouse gas (GHG) composed predominantly of methane and carbon dioxide produced from the anaerobic biodegradation of municipal solid waste in landfills. The amount of gas produced can be estimated using the Intergovernmental Panel on Climate Change methodology. Most sanitary landfills flare this potential renewable energy source, which is an unfortunate waste of a valuable resource. This study develops an optimization model for effective LFG utilization as a sustainable energy source based on economic and environmental considerations. The mixed integer linear programming model developed was applied to Seelong Sanitary Landfill, Malaysia, and led to profits 7.6 times higher than those currently gained. This enormous increase is due to the incorporation of renewable energy production in the new plan. In addition, the combined heat and power generation proposed is 2420 tons of oil equivalents, which is 0.0035% of the total energy production of Malaysia. Similarly, the LFG utilization leads to a national GHG reduction of 0.007%. Implementing this at the 14 sanitary landfills in the country will go a long way towards broadening the energy base while simultaneously reducing the carbon footprint of the nation. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 289–296, 2015

Abstract This study presents and evaluates the feasibility of a novel hybridization of modified Kalina cycle, reverse osmosis desalination, and low-temperature water electrolysis utilizing geothermal energy to yield power, distilled water, and hydrogen, respectively. The scientific impact of the current work has been improved considering the features of Sabalan flash-binary geothermal wells in Iran as a real model through a case study. In addition to designing a novel setup, the smart use of multi-heat recovery technique, modifying the base cycle, and utilizing a part of generated distilled water to produce hydrogen by the electrolyzer are the other structural originalities, distinguishing the current work from the previous studies. The suggested system is scrutinized via a parametric study and optimized based on a genetic algorithm. The parametric study demonstrated that the highest sensitivity of varying the performance criteria of the whole system is attributed to the change in flash tank pressure. Moreover, the multi-objective optimization led to achieving the exergy efficiency and trigeneration gain output ratio as 51.3% and 1.7 for the system, respectively. Furthermore, the system was able to produce 4795 kW of power, 5.3 kg/h of hydrogen, and 19.9 kg/s of distilled water.

Abstract Since the discovery of electricity, the demand for effective energy storage methods has increased. Energy storage devices are efficient tools used to manage power supply and produce resilient and cost-effective energy frameworks. Advanced technologies in modern economy and society require the application and design of inexpensive, highly efficient, and various infrastructures for energy storage systems. For instance, fuel cells, batteries, electrochemical capacitors, and conventional capacitors are used as energy storage devices because they can enhance energy or power densities. They can also supply energy within short or long periods. Their performances have also been improved. This review emphasizes carbon nanotubes as electrode materials for lithium-ion batteries and electrochemical capacitors. Different types of substrates and thin films may yield various structural and electrochemical properties of carbon nanotubes. This review also discusses their electrochemical performance observed through cyclic voltammetry and charge-discharge.