Cleaner Engineering and Technology最新文献

Post-consumer garments (PCG) wastes pose a significant concern in the textile value chain, primarily due to their environmental impact. Over the last few decades, recycling of PCG has garnered substantial attention from textile industrialists and researchers. This manuscript provides a comprehensive review of the progress in recycling and reusing the PCG over the last 15 years. A bibliometric analysis is presented from Scopus data from 2010 to February 2024 using various statistical tools. The aim is to present the existing challenges and prospects of PCG, including increased demand for garments recycling, advanced recycling technologies, reusing, circular economy initiatives, socio-economic advantages, bioenergy production, stringent regulations, and new business opportunities. Cutting-edge recycling techniques are presented, including the pyrolysis of PCG waste to generate bio-oil and the fabrication of nanofibers from PCG for enhanced filtration and protective clothes. Additionally, the production of thermal-insulating high-performance cloth from PCG is mentioned. Challenges, such as contamination in medical textile waste, the complexity of recycling, lack of infrastructure, reduced economic viability, and declining end product quality, are addressed. Guidelines to tackle challenges include proper segregation, identification, and disinfection to overcome contamination issues. This article is a credible resource for textile industry experts, academicians, and engineers interested in promoting garment recycling to assist in accomplishing the sustainable development goals (SDGs).

The emission of pollutants following electricity consumption is significant, and hospitals are major contributors to energy consumption. Hence, the aim of this study was a survey of electrical consumption rate and environmental pollutants emissions in selected hospitals. This descriptive-analytical and cross-sectional study was conducted over three years and based on electricity bills and bed indicators in selected hospitals in Tehran, Iran. Emissions Calculator software was used to calculate the emission of pollutants caused by electricity consumption. Kolmogorov Smirnov, Least Significant Difference (LSD), and one-way ANOVA tests were used to analyze the data. Results showed that the total average electricity consumption for each active day bed and occupied day bed was 9.6 and 13.6 times higher than the recommended standards. The average electricity consumption for each active day bed in hospitals A, B, and C was 13.7, 10.2, and 5 times higher than the standard value, respectively, while for occupied day beds, the consumption was 17.3, 15.1, and 8.5 times higher than the standard value, respectively. Additionally, the total electricity consumption in these hospitals resulted in the emission of 41837100 kg of CO2, 124815 kg of SO₂, 103699 kg of NOx, 9769 kg of CO, 4885 kg of PM₁₀, and 757 kg of VOCs into the environment. Based on the monthly active bed index and occupied day bed, there was a significant difference in the average electrical consumption among A, B, and C hospitals (p = 0.0001). Electricity consumption in the studied hospitals exceeds standards. Implementing optimal designs for lighting, heating, and cooling, along with energy optimization training, technical audits, and inspections are essential for both economic benefits and reducing environmental pollutants.

In response to its position as the fourth most populous country globally, Indonesia is exploring constructing nuclear power plants (NPPs) as a sustainable energy solution. A pivotal step in this initiative is selecting an appropriate NPP site. This study employs two Multi-Criteria Decision-Making (MCDM) methods, the Fuzzy Analytic Hierarchy Process (Fuzzy-AHP) and Fuzzy VIKOR, to identify the most suitable location for an NPP, focusing on socio-economic factors. The Fuzzy-AHP method is utilized to prioritize ten sub-criteria: transmission network, operating costs, economic impact, security, transportation network, legal considerations, the impact of tourism, land ownership, historical sites, and public acceptance. Following this, the Fuzzy VIKOR method leverages these prioritized criteria to evaluate two potential sites: East Kalimantan and West Kalimantan. The analysis reveals that security, transmission, and transportation networks emerge as the top priorities. The application of the Fuzzy VIKOR algorithm identifies West Kalimantan as the optimal site for NPP construction, evidenced by its lower VIKOR index of 0.3599, indicating a higher overall preference based on the evaluated criteria. The study demonstrates that the integration of Fuzzy-AHP and Fuzzy VIKOR methods prioritizes critical socio-economic factors and quantitatively assesses potential sites, offering a systematic and objective approach to support decision-making in NPP site selection.

Several research papers available in notable publications have been dedicated to different stages of helical gearbox. However, most of the previous investigation was focused on single stage and double stage helical gearboxes, while only a few studies covered triple stage helical gearboxes even though it has numerous advantages. Recently, the significance of three stage helical gearboxes has received a lot of attention among various research professionals associated in this area. In this study, comprehensive assessment was conducted on the current three stage helical gearbox literatures for examining most currently used distinct research designs, methods, tools & techniques, enablers & barriers and also identifying diverse research inclinations, major findings, shortcomings and suggesting the potential directions in futuristic research. This exploration perilously investigated 275 research papers on various stages of helical gearbox and conducted a structured literature review of 28 articles on three stage helical gearboxes published in various journals over the last two decades using content analysis methodology with inductive research approach. The major findings shows that there are immense potential for dominating the research field and several opportunities still exists for three stage helical gearboxes development, which in turn open up new avenues for experts and industries.

Plastics pollution is an overwhelming environmental problem that must be solved as soon as possible. Refining processes such as the Fluidized Catalytic Cracking (FCC) process with a global capacity of 14 million barrels per day, may help to solve it in the short term, as many scientists have already pointed out. Just by co-processing 5 wt % polyethylene waste in those units, 37 million tons per year of polyethylene could be eliminated from landfills and transformed into valuable fuels. However, refiners must be completely sure that processing polyethylene in their FCC plants will not cause any deleterious effects. That is the purpose of this paper.

Low density polyethylene waste was transformed into valuable hydrocarbons by co-processing in proportions of 5 and 10 wt % with heavy gasoil in an FCC pilot plant which operates as industrial FCC plants do. Polyethylene was completely converted mainly into naphtha and liquified petroleum gas; at 510 °C polyethylene was converted into naphtha (46 %), LPG (20 %), light cyclic oil (9 %), heavy cyclic oil (15 %), coke (6 %) and dry gas (4 %); at 530 °C, the order and proportions changed significantly, naphtha (43 %), LPG (35 %), heavy cyclic oil (0 %), light cyclic oil (2 %), coke (8 %) and dry gas (12 %); LPG olefinicity and naphtha research octane number increased slightly. No catalyst circulation problems nor clogging or plugging were observed. However, at the highest experimental reaction temperature (530 °C), dry gas yield increased to more than 4 wt %, this could be a problem for most of industrial plants since it may overload the wet gas compressor.

Agricultural biomass is a well-known renewable resource that has a high rate of recycling. Two of them are luffa sponge and corn husk/maize fibers. Luffa sponge may be effectively used to reinforce lightweight composite constructions because of its polypore structure. For this race, maize fiber is also appropriate. Surface modifications for both of the fibers are needed for increasing mechanical strength with higher interfacial bonding with the matrix materials of composite manufacturing. This investigation involved treating both materials with 5 g/L, 10 g/L, and 15 g/L of NaOH in order to describe the alterations occurring on their physio-chemical characteristics. The therapy lasted 60 min and was administered at 90 °C. Following that, acetic acid was used to neutralize the samples. The ASTM D1445 technique was used to measure the bundle fibers' breaking force and elongation, and the ASTM D570 procedures were used in order to determine the water absorption variation % in the treated samples. The FTIR test and SEM examination revealed the contaminants that were eliminated from the surface of Luffa and Maize fibers. The test findings demonstrated improved modification behaviors for the 15 g m/L treated fibers, which had an elongation percentage of 3.02% and an equivalent breaking force of 5.12 kg for the Luffa fiber and 5.72 kg for the maize fiber. Natural contaminants were eliminated as a result of variations in functional group intensity shown in the FTIR pictures. However, SEM pictures showed that the surface smoothed out for samples treated with 15 g per liter of NaOH, which may be the cause of the fiber's brittle interlocking with the matrix components. Moreover, water absorbency rose by over 300% compared to the untreated fibers. In summary, samples treated with 10 g/L NaOH might serve as superior reinforced materials of composite for both types of fibers.

This study investigates the characteristics of blended Palm Oil Fuel Ash (POFA) concrete admixed with silica fume (SF) and precipitated silica (SP) as a cement replacement material for Portland Composite Cement (PCC). The study aims to evaluate the potential of precipitated silica extracted from POFA as an alternative to commercial silica fume in enhancing the properties of palm oil fuel ash concrete. Four different mixes were studied, including a control mix with PCC and three mixes with varying amounts of POFA, SF, and SP. The study analyzed the fresh properties, compressive strength, strength activity index, tensile strength, and microstructure of the concrete. The results showed that the addition of SF and SP increased the compressive strength of the POFA concrete by 23.34% and 38.11% respectively at 28 days. The strength activity index was also higher in the mixes with silica, indicating a higher pozzolanic activity at early ages. The tensile strength and porosity of the concrete were also improved with the addition of silica. The SEM and FTIR analysis confirmed that the addition of silica, especially precipitated silica, improved the microstructure of the concrete. The study concludes that the precipitated silica from POFA has the potential to be used as a cement replacement or additive in POFA concrete manufacturing in Asian countries where POFA is abundantly available.

Supplementary cementitious materials are beneficial in improving performance and lessening the cement consumption with highly lessening CO₂ emission. Many researchers used blast furnace slag, bentonite, and active limestone separately or two of them together to improve the performance of cementing materials, however, it is not well known how all react together in cement composite materials. So, the present study used modeling and optimizing the replacement of blast furnace slag, raw bentonite, and active limestone each by the doses of 0 to 20% to maximize strength and minimize the fresh bulk density of cementing materials by central composite design-response surface method (CCD-RSM). The results found, the employment of blast furnace slag, bentonite, and active limestone in the cement composite materials generally lessens the early strength compared to the control mixture. However, the replacement of blast furnace slag and active limestone by 20% significantly improves the 28-days compressive strength while employing raw bentonite by 20% reduced compressive strength by 6.45% compared to the control mixture. However, blending raw bentonite with active limestone by half improved the compressive strength. Besides these, the substitution of bentonite and active limestone reduces the fresh bulk density and flexural strength than the control mixture. Generally, the study optimized depending on the criteria of maximizing strength and minimizing fresh density and found the mix design replacement of blast furnace slag 1.01%, raw bentonite 5.30%, and active limestone 20% that improves 28 days compressive strength simultaneously reduces fresh bulk density in addition to replacing more than 54 different optimized design mix results.

Radiation Shielding Concrete plays a critical role in safeguarding against ionizing radiation, in nuclear power plants, medical facilities, and other radiation-sensitive environments. This review paper presents a comprehensive examination of radiation shielding concrete development, highlighting a novel approach that incorporates a diverse range of natural and industrial materials. Traditional radiation shielding concrete formulations rely heavily on virgin materials, contributing to environmental degradation and resource depletion. In contrast, this paper explores the innovative use of natural materials, industrial by-products, and waste materials, emphasizing the environmental sustainability and resource efficiency of such approaches. By harnessing these alternative materials, the paper outlines how radiation shielding concrete production can significantly reduce its ecological footprint while maintaining or even enhancing its radiation shielding capabilities. The paper delves into the functional aspects, composition variations, and performance characteristics of radiation shielding concrete, providing a holistic perspective on the diverse materials employed. Additionally, it thoroughly examines the factors influencing the effectiveness of radiation shielding concrete in nuclear power plants. Furthermore, this review discusses recent developments and advancements in radiation shielding concrete, offering insights into the cutting-edge research and innovations that are shaping the future of radiation shielding. The integration of natural and industrial materials presents promising avenues for enhancing the versatility, cost-effectiveness, and sustainability of radiation shielding concrete.