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The growing population and increasing urbanization have led to a surge in domestic wastewater generation, posing significant challenges for effective and sustainable treatment. The present study demonstrates a novel and sustainable approach for the onsite treatment of domestic wastewater using an integrated settler-based biofilm reactor (ISBR) with efficient biogas generation. The ISBR provides an optimized environment for the growth of biofilm, facilitating the removal of organic pollutants and pathogens. Moreover, the ISBR enables the recovery of a valuable resource in the form of biogas, thus enhancing the overall utility of the treatment process. The performance of the ISBR was comprehensively evaluated at laboratory scale through treating the actual domestic wastewater generated from the hostel of Manipal University Jaipur. The ISBR system was operated under an ambient environment at a hydraulic retention time (HRT) of 24 h. The results demonstrated remarkable efficiency in terms of chemical oxygen demand (COD), total suspended solids (TSS), and coliforms removal, with average removal efficiency being more than 90%. According to the COD mass balance analysis, 48.2% of the influent COD was recovered as bioenergy. The chromatogram revealed a high percentage of methane gas in the collected biogas sample. The field emission scanning electron microscope (FESEM) analysis of the accumulated sludge in the ISBR system depicted the morphology of methanogenic bacteria. Both the experimental and theoretical results confirmed the feasibility and sustainability of the ISBR system at the onsite level.

Abstract Liquid fuels are likely to remain the main energy source in long-range transportation and aviation for several decades. To reduce our dependence on fossil fuels, liquid biofuels can be blended to fossil fuels – or used purely. In this paper, coconut methyl ester, standard diesel fuel (EN590:2017), and their blends were investigated in 25 V/V% steps. A novel turbulent combustion chamber was developed to facilitate combustion in a large volume that leads to ultra-low emissions. The combustion power of the swirl burner was 13.3 kW, and the air-to-fuel equivalence ratio was 1.25. Two parameters, combustion air preheating temperature and atomizing air pressure were adjusted in the range of 150–350 °C and 0.3–0.9 bar, respectively. Both straight and lifted flames were observed. The closed, atmospheric combustion chamber resulted in CO emission below 10 ppm in the majority of the cases. NO emission varied between 60 and 183 ppm at straight flame cases and decreased below 20 ppm when the flame was lifted since the combustion occurred in a large volume. This operation mode fulfills the 2015/2193/EU directive for gas combustion by 25%, which is twice as strict as liquid fuel combustion regulations. The 90% NO emission reduction was also concluded when compared to a lean premixed prevaporized burner under similar conditions. This favorable operation mode was named as Mixture Temperature-Controlled (MTC) Combustion. The chemiluminescent emission of lifted flames was also low, however, the OH* emission of straight flames was clearly observable and followed the trends of NO emission. The MTC mode may lead to significantly decreased pollutant emission of steady-operating devices like boilers, furnaces, and both aviation and industrial gas turbines, meaning an outstanding contribution to more environmentally friendly technologies.

Activities involving land use, land-use change,forestry, and agriculture (LUCF) can help reducegreenhouse gas (GHG) concentrations in the atmosphereby increasing biotic carbon storage, by decreasing GHGemissions, and by producing biomass as a substitutefor fossil fuels. Potential activities includereducing rates of deforestation, increasing landdevoted to forest plantations, regenerating secondaryforest, agroforestry, improving the management offorests and agricultural areas; and producing energycrops.Policymakers debating the inclusion of a variety ofLUCF activities in the Clean Development Mechanism(CDM) of the Kyoto Protocol need to consider themagnitude of the carbon contribution these activitiescould make. Existing estimates of the cumulative GHGoffset potential of LUCF activities often take aglobal or regional approach. In contrast, land-usedecisions are usually made at the local level anddepend on many factors including productive capacityof the land, financial considerations of thelandowner, and environmental concerns. Estimates ofGHG offset potential made at a local, or at mostcountry, level that incorporate these factors may belower, as well as more useful for policy analyses,than global or large regional estimates. Whilecountry-level estimates exist for forestry activities,similar estimates utilizing local information need tobe generated for agricultural activities and biofuels,as well as for the cumulative potential of all LUCFactivities in a particular location.

Renewable energy has become more popular since it is cost-effective and more efficient than conventional energy sources. Biomass-based renewable energy is primarily used in emerging economies to ensure environmental sustainability. This study examines the asymmetric correlation between biomass energy consumption and CO2 emissions in the top-10 biomass energy consumer countries (Brazil, Canada, Thailand, China, Italy, India, Germany, USA, UK, and Japan). A new approach "Quantile-onQuantile (QQ)" is employed by utilizing the data from 1991 to 2018. Biomass energy consumption, with the exception of Thailand, significantly mitigates CO2 emissions at various quantiles in selected countries. As a robustness check, we used the quantile regression test, whose findings are consistent with the outcomes from the quantile-on-quantile method. However, the degree of asymmetry in the biomass energy-CO2 nexus varies by country, necessitating extra attention and government vigilance when developing biomass energy and environmental policies.

This paper proposes a sustainability-oriented multiobjective optimization model for siting and sizing DG plants in distribution systems. Life cycle exergy (LCE) is used as a unified indicator of the entire system’s environmental sustainability, and it is optimized as an objective function in the model. Other two objective functions include economic cost and expected power loss. Chance constraints are used to control the operation risks caused by the uncertain power loads and renewable energies. A semilinearized simulation method is proposed and combined with the Latin hypercube sampling (LHS) method to improve the efficiency of probabilistic load flow (PLF) analysis which is repeatedly performed to verify the chance constraints. A numerical study based on the modified IEEE 33-node system is performed to verify the proposed method. Numerical results show that the proposed semilinearized simulation method reduces about 93.3% of the calculation time of PLF analysis and guarantees satisfying accuracy. The results also indicate that benefits for environmental sustainability of using DG plants can be effectively reflected by the proposed model which helps the planner to make rational decision towards sustainable development of the distribution system.

In this paper, metabolic evaluation has been employed for better understanding the trends in urban environmental changes. Due to the urban activities cause impacts not only on local level but also a broader scale, Hybrid Emergy-LCA (HEML), a combining approach of Emergy Analysis (EMA) and Life Cycle Assessment (LCA) is structured to quantitatively investigate the mechanism. For the similarity across many emerging cities in China, a large-scale sub-urban residential area named Tian Tongyuan (Try) in Beijing was chosen for testing the HEML. Objective indicators of live quality and negative impacts are both considered. Analysis indicates that the household Emergy input of TTY is 1.76E+16 sej/yr, while the prominent environmental impact is induced by Photochemical Oxidant Creation Potentials (POCP), 4.58E+05 g ethane eq./yr. The sustainable performance constructed by its live quality and environmental impacts of TTY is found as 98.80% as that of Beijing average. Mitigation polices on the building sector should be proposed because of its dominating impacts among various consuming ends of energy and materials. (C) 2009 Elsevier B.V. All rights reserved.

Abstract Dolomite, a naturally occurring Ca-based sorbent, shows superior recycling stability in carbonation/calcination cycles for CO2 capture. However, the separation between Ca and Mg in sorbent during recycling weakens the resistance for sintering from MgO, leading to a drastic reduction in the CO2 carrying activity (spent sorbent). This paper presents a novel method for the reactivation of spent dolomite sorbents. Notable activity recovery is achieved by ball milling of the spent sorbent with H2O and dry ice. Powder X-ray diffraction (XRD) results confirm the transformation from oxide (CaO/MgO) to carbonate (CaCO3/CaMg(CO3)2), so that the segregated Ca and Mg in spent sorbent are re-mixed at the atomic level, which is mainly responsible for this effective reactivation. Water plays an irreplaceable role in this process by providing a liquid environment to accelerate the diffusion of the reactants and ionic reactions. In addition, thermogravimetric analysis was carried out on a series of samples with different ball-milling times to determine the suitable reactivation conditions for CO2 capture.

Abstract Hydrogen is considered a potential game changer for world energy systems and a solution to climate change concerns, as it generates zero waste and it is suited for power generation and transportation. Despite its several advantages, there are significant technical challenges in deploying a stable hydrogen economy including improving its process efficiencies, lowering production costs, maintaining cost-effective transmission and distribution, and exploiting inexpensive and sustainable feedstocks. In this context, a detailed study was conducted to analyze the production sources, technologies, storage and transport systems, and global potential exportable feedstocks to produce hydrogen. A comprehensive analysis of current hydrogen production technologies with their energy efficiencies and hydrogen selling prices was reported in this study. Various hydrogen production technologies with their capital investments and CO2 emissions were also presented. Potential feedstocks for hydrogen production were identified and analyzed through a product space model, which characterizes a network of global exportable products based on their similarities and productive knowledge. It was established that the hydrogen production feedstocks and sources currently used are primarily available in six countries: the United States of America, France, Russia, Sweden, the Netherlands, and Spain. Broadly, the results revealed that the United States of America and Russia shared the highest hydrogen feedstock exports, indicating a higher probability of hydrogen production in these countries. Except for Russia, all the studied countries fell in the most desired quadrant, indicating that they can move in all product space directions to exploit unexplored hydrogen feedstocks for better sustainable economic growth.