Performance evaluation and optimization of fluidized bed boiler in ethanol plant using irreversibility analysis

This research aims to evaluate the performance of a fluidized bed boiler in an ethanol production plant through exergy and irreversibility analysis. The study also includes the optimization of the pre-heater and the deaerator in order to improve the system efficiency. Operational data from the ethanol production plant was collected between 2015 and early 2016. The total exergy derived from the fuel was determined to be 7783 kJ/s, while the exergy efficiency of the system was found to be 26.19%, with 2214 kJ/s used in steam production, while 71.55% was lost to component irreversibility and waste heat from the pre-heater. The exergy efficiencies of individual components of the system such as the boiler, deaerator, and pre-heater were found to be 25.82%, 40.13%, and 2.617%, respectively, with the pre-heater having the lowest efficiency. Thus, the pre-heater has the highest potential to significantly improve the efficiency of the boiler system. The optimization of the pre-heater shows that a rise in temperature in the outlet of the pre-heater positively affects the exergy efficiency of the deaerator

Exergy intensity and environmental consequences of the medical face masks curtailing the COVID-19 pandemic: Malign bodyguard?

On January 30, 2020, the World Health Organization identified SARS-CoV-2 as a public health emergency of global concern. Accordingly, the demand for personal protective equipment (PPE), including medical face masks, has sharply risen compared with 2019. The new situation has led to a sharp increase in energy demand and the environmental impacts associated with these product systems. Hence, the pandemic's effects on the environmental consequences of various PPE types, such as medical face masks, should be assessed. In light of that, the current study aimed to identify the environmental hot-spots of medical face mask production and consumption by using life cycle assessment (LCA) and tried to provide solutions to mitigate the adverse impacts. Based on the results obtained, in 2020, medical face masks production using fossil-based plastics causes the loss of 2.03 × 103 disability-adjusted life years (DALYs); 1.63 × 108 PDF*m2*yr damage to ecosystem quality; the climate-damaging release of 2.13 × 109 kg CO2eq; and 5.65 × 1010 MJ damage to resources. Besides, annual medical face mask production results in 5.88 × 104 TJ demand for exergy. On the other hand, if used makes are not appropriately handled, they can lead to 4.99 × 105 Pt/yr additional damage to the environment in 2020 as determined by the EDIP 2003. Replacement of fossil-based plastics with bio-based plastics, at rates ranging from 10 to 100%, could mitigate the product's total yearly environmental damage by 4–43%, respectively. Our study calls attention to the environmental sustainability of PPE used to prevent virus transmission in the current and future pandemics

To what extent do waste management strategies need adaptation to post-COVID-19?

The world has been grappling with the crisis of the COVID-19 pandemic for more than a year. Various sectors have been affected by COVID-19 and its consequences. The waste management system is one of the sectors affected by such unpredictable pandemics. The experience of COVID-19 proved that adaptability to such pandemics and the post-pandemic era had become a necessity in waste management systems and this requires an accurate understanding of the challenges that have been arising. The accurate information and data from most countries severely affected by the pandemic are not still available to identify the key challenges during and post-COVID-19. The documented evidence from literature has been collected, and the attempt has been made to summarize the rising challenges and the lessons learned. This review covers all raised challenges concerning the various aspects of the waste management system from generation to final disposal (i.e., generation, storage, collection, transportation, processing, and burial of waste). The necessities and opportunities are recognized for increasing flexibility and adaptability in waste management systems. The four basic pillars are enumerated to adapt the waste management system to the COVID-19 pandemic and post-COVID-19 conditions. Striving to support and implement a circular economy is one of its basic strategies.</p

China's climate change mitigation and adaptation strategies for decreasing environmental impacts in the agricultural sector

While the agricultural sector plays a profound role in food provisioning, achieving sustainability poses formidable challenges worldwide. In this context, this study projects the environmental impacts of China's agricultural sector in the years 2030 and 2050 in line with the framework of shared socioeconomic pathways (SSPs) in comparison to the base period from 1994 to 2019. Accordingly, a spatiotemporal assessment was undertaken by employing the Life Cycle Assessment (LCA) method in seven geographical regions across China. In the base period, China's agricultural sector experienced increasing environmental impacts, between ∼10 % to ∼30 % from 1994 to 2014, while it decreased by ∼8 % from 2014 to 2019. On average, 33 % of the total environmental challenges impacted the eastern region of China. The projections also indicate that the transition towards sustainability (SSP1) could reduce environmental impacts by ∼52 % in 2030 and by ∼76 % in 2050, in comparison to 2019. Conversely, adopting regional rivalry strategies (SSP3) can result in a ∼ 3 % increase in environmental impacts in 2030 and a ∼ 30 % decrease in 2050 compared to 2019. The findings underscore the decisive role of agricultural management policies in controlling environmental impacts and facilitating the decarbonization of the Chinese agricultural sector.</p

Multi responses optimization of decarboxylation process of Free Fatty Acid (FFA) into biodiesel using Grey Relational Analysis (GRA)

Grey Relational Analyses (GRA) was utilized to determine optimal setting parameters of Free Fatty Acid (FFA) conversion from into hydrocarbon chain by decarboxylation process. The considered setting parameters were voltage and acetic acid (CH3COOH) concentration. Decarboxylation process occurred by adding acetic acid as the ion contributor for the dimerization process. In order to facilitate FFA well ionized, electrolysis was employed during the decarboxylation with voltage varied from 10 Volt to 25 Volt. The concentration of Acetic Acid varied from 0.5M to 1.5M for an optimum condition with a high yield. Decarboxylation reaction took place at 130ºC for 1 hour. The experiments were carried out by using full factorial design and multi responses considering % Yield, specific gravity (spgr), °API, viscosity, and Net Heating Value (NHV). Grey Reasoning Grade (GRG) was used to analysis multi responses. The setting parameters of sequence seven (A2 B3) has the highest GRG. Analysis of variance (ANOVA) results indicated that acetic acid concentration was contributing parameter. The optimal level for acetic acid concentration based on polynomial regression model was found to be 1.325 M

Pretreatment of lignocelluloses for enhanced biogas production: A review on influencing mechanisms and the importance of microbial diversity

Received 13 August 2019; Received in revised form 10 July 2020; Accepted 28 July 2020, Available online 11 August 2020.As one of the most efficient methods for waste management and sustainable energy production, anaerobic digestion (AD) countenances difficulties in the hydrolysis of lignocelluloses biomass. Different pretreatment methods have been applied to make lignocelluloses readily biodegradable by microorganisms. These pretreatments can affect biogas yield by different mechanisms at molecular scale, including changes in chemical composition, cellulose crystallinity, degree of polymerization, enzyme adsorption/desorption, nutrient accessibility, deacetylation, and through the formation of inhibitors. The present article aims at critically reviewing the reported molecular mechanisms affecting biogas yield from lignocelluloses via different types of pretreatments. Then, a new hypothesis concerning the impact of pretreatment on the microbial community developed (throughout the AD process from an identical inoculum) was also put forth and was experimentally examined through a case study. Four different leading pretreatments, including sulfuric acid, sodium hydroxide, aqueous ammonia, and sodium carbonate, were performed on rice straw as model lignocellulosic feedstock. The results obtained revealed that the choice of pretreatment method also plays a pivotally positive or negative role on biogas yield obtained from lignocelluloses through alteration of the microbial community involved in the AD. Considerable changes were observed in the archaeal and bacterial communities developed in response to the pretreatment used. Sodium hydroxide, with the highest methane yield (338 mL/g volatile solid), led to a partial switch from acetoclastic to the hydrogenotrophic methane production pathway. The findings reported herein undermine the default hypothesis accepted by thousands of previously published papers, which is changes in substrate characteristics by pretreatments are the only mechanisms affecting biogas yield. Moreover, the results obtained could assist with the development of more efficient biogas production systems at industrial scale by offering more in-depth understanding of the interactions between microbial community structure, and process parameters and performance

Multivariable optimization of carbon nanoparticles synthesized from waste facial tissues by artificial neural networks, new material for downstream quenching of quantum dots

In this study, water-soluble carbon nanoparticles (CNPs) were synthesized by using waste facial tissue as a non-recyclable waste and the efficiency of CNPs in quenching mechanism of cadmium-telluride quantum dots (QDs) was investigated. In addition, CNPs synthesis was modeled by using artificial neural networks (ANN). To find the optimum model, ANN was trained by using different algorithms. Then, the generated models were statistically assessed and subsequently, the capability of the selected model for predicting the mean diameter size of the nanoparticles was verified. Based on the results, the model GA-4-7-1 had the most optimal statistical characteristics. Furthermore, the most pronounced effect on mean diameter size was associated to HNO3 concentration while temperature demonstrated the least influence. Moreover, the quenching study confirmed the capability of the synthesized CNPs in quenching QDs

Potential of Acid-Activated Bentonite and SO3H-Functionalized MWCNTs for Biodiesel Production From Residual Olive Oil Under Biorefinery Scheme

Application of acid-activated bentonite and SO3H-functionlized multiwall carbon nanotubes (SO3H-MWCNTs) for lowering free fatty acids (FFAs) content of low-quality residual olive oil, prior to alkali-catalyzed transesterification was investigated. The used bentonite was first characterized by Scanning Electron Microscopy (SEM), Inductively Coupled Plasma mass spectrometry (ICP-MS), and X-ray fluorescence (XRF), and was subsequently activated by different concentrations of H2SO4 (3, 5, and 10 N). Specific surface area of the original bentonite was measured by Brunauer, Emmett, and Teller (BET) method at 45 m2/g and was best improved after 5 N-acid activation (95–98°C, 2 h) reaching 68 m2/g. MWCNTs was synthesized through methane decomposition (Co-Mo/MgO catalyst, 900°C) during the chemical vapor deposition (CVD) process. After two acid-purification (HCl, HNO3) and two deionized-water-neutralization steps, SO3H was grafted on MWCNTs (concentrated H2SO4, 110°C for 3 h) and again neutralized with deionized water and then dried. The synthesized SO3H-MWCNTs were analyzed using Fourier-Transform Infrared Spectroscopy (FTIR) and Transmission Electron Microscopy (TEM). The activated bentonite and SO3H-MWCNTs were utilized (5 wt.% and 3 wt.%, respectively), as solid catalysts in esterification reaction (62°C, 450 rpm; 15:1 and 12:1 methanol-to-oil molar ratio, 27 h and 8 h, respectively), to convert FFAs to their corresponding methyl esters. The results obtained revealed an FFA to methyl ester conversion of about 67% for the activated bentonite and 65% for the SO3H-MWCNTs. More specifically, the acid value of the residual olive oil was decreased significantly from 2.5 to 0.85 and 0.89 mg KOH/g using activated bentonite and SO3H-MWCNTs, respectively. The total FFAs in the residual olive oil after esterification was below 0.5%, which was appropriate for efficient alkaline-transesterification reaction. Both catalysts can effectively pretreat low-quality oil feedstock for sustainable biodiesel production under a biorefinery scheme. Overall, the acid-activate bentonite was found more convenient, cost-effective, and environment-friendly than the SO3H-MWCNTs

Sustainable economic growth potential of biomass-enriched countries through bioenergy production: State-of-the-art assessment using product space model

The current study aims to examine the economically viable biomass feedstocks for bioenergy generation and their export potential. The Product Space Model (PSM) is the primary tool used to achieve the aim by accomplishing certain objectives. The study’s findings show that Pakistan has abundant biomass resources for energy production. Canola oil, leather flesh wastes, and poultry fattening show the highest PRODY values, 46,735, 44,438, and 41,791, respectively. These have high-income potential and are considered feasible for export after meeting local energy demand. While goat manure, cashew nutshell, and cotton stalk show lower income potential having values of 3,641, 4,225, and 4,421, respectively. The biowastes having low-income potential are more beneficial to utilize in energy generation plants within the country. The United States is observed to make the most sophisticated products, indicated by an EXPY value of 36296.89. While the minimum level of sophistication is observed for Indonesia, as revealed by its EXPY value of 22235.41 among all considered countries. The PSM policy map analysis of the current study shows that Pakistan and Argentina are located in the Parsimonious Policy quadrant, suggesting shifting toward unexploited products closely related to the existing export baskets. Although the United States, China, India, Indonesia, and Brazil are found in the most desired Let-it-be Policy quadrant. They have more room to diversify their industries and enhance their export potential. The study has practical applications in economic, social, and environmental perspectives, focusing on economic, clean, and sufficient energy. Furthermore, exportable biomass feedstocks are identified to strengthen the economy. Further research must be conducted to evaluate other indicators of the PSM to explore the proximity aspect of PSM, as it would provide a clearer picture of bioenergy and biomass export prospects