Waste Disposal & Sustainable Energy最新文献

The atomization characteristics play a key role in the highly efficient combustion of pyrolysis oil derived from waste tires. In this study, the fuel properties of tire pyrolysis oil (TPO) were initially studied, and then a high-speed camera and a phase Doppler particle analyzer were employed to characterize the atomization feature of TPO. The influence of pressure and nozzle orifice diameter on atomization characteristics such as spray angle, droplet velocity, and droplet size distribution was investigated. The results showed that TPO had a high calorific value of about 43.6 MJ/kg and a low viscosity of 3.84×10^–6 m²/s at 40 °C, which made it have the potential to be used as an alternative fuel. Higher pressure expanded the spray angle and extended the spray in both the axial and radial directions. With increasing pressure, spray angle and droplet velocity raised, and the increase in crushing effect of air reduced the Sauter mean diameter (SMD) of the droplets. To obtain proper atomization quality for combustion, the pressure is expected to be higher than 1.25 MPa. With increasing nozzle orifice diameter, droplet velocity increased, and the SMD of the droplets increased as well due to weakened crushing effect of the orifice. Therefore, the pressure must be increased to maintain the atomization quality when using a nozzle with a larger orifice. Due to the lower viscosity, the velocity and particle size distribution of TPO droplets after atomization were smaller than those of diesel droplets. The extremely small carbon black contained in TPO also contributed to the breaking of droplets and played a certain role in the size reduction of the oil droplets, but it may cause the risk of nozzle blockage. In summary, TPO showed great atomization characteristics for alternative fuel applications.

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Scientific studies have focused on environmentally friendly solutions as effective as the reuse of crop products owing to plastic-waste problems in recent years. This issue is the main driving force for upcoming academic research attempts in waste valorization-related studies. Herein, we integrated an aqua-waste, mussel shell (MS), as a bioadditive form into green thermoplastic polyurethane (TPU) green composites. Tuning of the MS surface was performed to achieve strong adhesion between composite phases. The surface functionalities of MS powders were evaluated via infrared spectroscopy and scanning electron microscopy (SEM) images. Composite samples were prepared by melt-compounding followed by injection molding techniques. It was confirmed by morphological analysis that relatively better adhesion between the phases was achieved for composites involving surface-modified MS compared to unmodified MS. Tensile strength and Young’s modulus of surface-modified MS-filled composites were found to be higher than those of unmodified MS, whereas the elongation at break shifted to lower values with MS inclusions. The shore hardness of TPU was remarkably improved after being incorporated with silane-treated MS (AS-MS). Stearic acid-treated MS (ST-MS) additions resulted in an enhancement in the thermal stability of the composites. Thermo-mechanical analysis showed that the storage moduli of composites were higher than those of unfilled TPU. ST-MS additions led to an increase in the characteristic glass transition temperature of TPU. Melt flow index (MFI) of neat TPU was highly improved after MS loading regardless of modification type. According to the wear test, surface modification of MS displayed a positive effect on the wear resistance of TPU. As the water absorption data of the composites were evaluated, the TPU/AS-MS composite yielded the lowest water absorption. The silane layer on MS inclusion promoted water repellency of composites due to the hydrophobicity of silane. The results of the biodegradation investigation demonstrated that adding unmodified and/or modified MS to the TPU matrix increased the biodegradation rate. The test results at the end of a 7-week period of biodegradation with a soft-rot fungus implied that the composite materials were more biodegradable than pure TPU. Silane modification of MS exhibited better performance in terms of the characterized properties of TPU-based composites.

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Coal gangue (CG) is an environmental waste that faces an urgent demand for disposal in China. The utilization of CG in construction materials has broad application prospects and gained increasing interest. However, the poor compatibility of polycarboxylate superplasticizer (PCE) with CG powder hinders its efficiency in a wide range of applications. Here, this paper attempts to improve the compatibility of PCE with CG powder in cement paste based on the regulation of aggregation and the adsorption behavior of PCE. Dynamic light scattering (DLS) and fluorescence spectroscopy tests were carried out to understand the improved mechanism. The results indicated that the addition of CG powder increases the ionic strengths of the cement liquid phase, which makes PCE tend to aggregate at a lower concentration compared with no CG powder introduction. Adding (CH₃COO)₂Cu is beneficial for enhancing the workability of cement paste by reducing PCE aggregation while maintaining the compressive strength of cement specimens. Therefore, (CH₃COO)₂Cu extra addition can be regarded as an effective and sustainable way to improve the workability of cement paste with CG powder.

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The present research focuses on addressing the faster depletion of fossil fuels and environmental pollution in addition to the energy crisis that hinders the progress of a nation. In the current research, waste banana leaves were considered as substrates for biogas production. Biogas is taken as the primary fuel in dual fuel (DF) operations to maximize possible diesel savings. The performance and combustion assessment were executed in a low heat rejection (LHR) engine using 5% diethyl ether by volume blended with diesel (5DEE) as pilot fuel. The combustion attributes of the engine reveal that the apex of net heat release rate (NHRR) curve retarded a bit as compared to apex of base result. The peak cylinder pressure was noted to be 6.19 MPa in the LHR engine running with 5DEE + biogas at 11.7° crank angle (CA) after top dead center (aTDC) compared to 5.23 MPa for the diesel alone operation at the same position. The apex point for NHRR was observed to be 54.51 J (°)⁻¹ for 5DEE + biogas in LHR engine positioned at 3.2° aTDC. The brake thermal efficiency at full engine load operation decreased by 12.7% and 5.2% for biogas substitutions of 0.8 kg h⁻¹ with diesel and 5DEE, respectively, compared to the base result. The smoke opacity and nitric oxide emissions were reduced during the DF run accompanied by diethyl ether as a fuel additive.

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Phosphorus-containing compounds are considered as the potential alternatives of traditional inhibitors for suppressing the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), but the suppression characteristics are scarcely studied. In this study, ammonium dihydrogen phosphate (ADP) was selected as the inhibitor to inhibit the PCDD/F formation via de novo synthesis at 350 °C. The influence of oxygen content and addition method on PCDD/F inhibition was systematically investigated by means of statistical analysis and morphological characterization. The results showed that oxygen enhanced the formation of PCDD/Fs from 1470 ng g⁻¹ (9.78 ng I-TEQ g⁻¹) to 2110 ng g⁻¹ (14.8 ng I-TEQ g⁻¹). ADP significantly inhibited the PCDD/F formation, with inhibition efficiencies ranging from 82.0% to 97.7%. Herein, a higher oxygen content and the premixed way intensified the suppression effect. Dibenzo-p-dioxin (DD)/dibenzofuran (DF) chlorination was proven to be effectively suppressed while chlorophenol (CP) route was not obviously influenced. With the addition of ADP, Cl source was significantly reduced and the formation of organic Cl was effectively inhibited. Also, it decreased the proportion of C–O/C=N and C=O, revealing the efficient inhibition of carbon oxidation. Meanwhile, the formation of copper phosphate and copper pyrophosphate was observed in XPS (X-ray photoelectron spectroscopy) spectra, indicating that the catalytic metal Cu was chelated and passivated by ADP. The premixed way had a better effect on reducing Cl resources, inhibiting oxidation and chelating metals, due to the direct contact with inhibitor. However, the separation method could only depend on the decomposed gases, resulting in a lower inhibition efficiency.

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This review looks over the current construction and demolition waste management (C&DWM) situations by scrutinizing the definition, classification, components, compositions, generated sources and causes, impacts of generated construction and demolition wastes (C&DWs), waste management hierarchy (WMH), 3R principles (Reduce, Reuse, and Recycle), Circular Economy (CE), frameworks, tools, and approaches of C&DWM. After reviewing the literature this study contributes to the literature by the following means: (a) suitable working definitions of C&DW and C&DWM are provided, (b) an expanded WMH for construction and demolition operations is presented, (c) frameworks of C&DWM are identified and listed as follows: frameworks based on WMH, including 3R principles and CE concept, frameworks focusing on the quantification, estimation, and prediction of generated C&DW, frameworks focusing on effective and sustainable C&DWM, frameworks focusing economic, social, and environmental performance assessment, frameworks based on multi-criteria analysis (MCA), frameworks based on post-disaster recovery period, and other miscellaneous frameworks, and (d) four categories of tools utilized in C&DWM are identified and explained, namely, approaches employed in C&DWM, information technology (IT) tools employed in C&DWM, multi-criteria decision analysis (MCDA) tools employed in C&DWM, and C&DWM technologies. Moreover, this study also found that CE, and green rating system (GRS) are widely used approaches, Building Information Modeling (BIM), Radio Frequency Identification (RFID), Geographic Information System, and Big Data are the extensively used IT tools, Analytical Hierarchy Process, FUZZY, TOPSIS (Technique for Order Preference by Similarity to the Ideal Solution), Weighted Summation, Elimination and Choice Expressing the Reality II, Elimination and Choice Expressing the Reality III, Evaluation of Mixed Data, and REGIME (REG) are the widely used MCA tools in C&DWM, and Prefabricated Construction and Modular Construction are broadly used C&DWM technologies. Furthermore, it has been observed that the application of the Analytic Networking Process (ANP) and hybridization of ANP, FUZZY, and TOPSIS tools do not catch considerable attention in the literature for conducting MCA, although it yields more precise outcomes. Additionally, most previous research has focused on the estimation of generated C&DW, but less attention has been given to forecasting the generated C&DW due to inadequate available C&DW data. This review article also assists C&DWM practitioners, academics, stakeholders, and contractors in choosing appropriate frameworks and tools for C&DWM while managing C&DW.

Polyester/cotton (PET/C) blended fabric wastes are produced daily in huge amounts, which constitutes an economic loss and an environmental threat if it is not reused appropriately. Modern textile waste recycling technologies put much effort into developing fabric materials with unique properties, such as bioactivity or new optical goods based on modern technologies, especially nano-biotechnology. In this study, zinc oxide nanoparticles (ZnO-NPs) were biosynthesized using the aqueous extract of Dunaliella sp. and immobilized on PET/C waste fabrics after enzymatically activated with cellulases. The produced Dunaliella-ZnO-NPs (10–20 nm with a spherical shape) were characterized by High-resolution transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FTIR), X-Ray diffraction analysis (XRD), and Scanning electron microscopy-energy dispersive X-ray analyzer (SEM-EDAX), and some functional groups, such as CH, CO, NH, and CN (due to the presence of carboxyl, proteins and hydroxyl groups), were detected, revealing the biosynthesis of ZnO-NPs. The analysis showed that the resulting ZnO-NPS had potent antimicrobial effects, Ultraviolet (UV) protection capabilities, and no cytotoxic effects on the normal human fibroblast cell line (BJ1). On the other hand, enzymatic treatments of PET/C fabric waste with cellulases enhanced the immobilization of biosynthetic nanoparticles on their surface. Modified PET/C fabrics loaded with Dunaliella-ZnO-NPs showed antibacterial and UV protection capabilities making them an eco-friendly and cost-effective candidate for numerous applications. These applications can include the manufacture of active packaging devices, wastewater treatment units, and many other environmental applications.

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Emission source characterization and meteorological influence are the key aspects to gain insight into the ground ozone governing mechanisms. Receptor-based data analysis techniques help in comprehending local ozone fluctuations in the lack of accurate information on the emission characteristics. Through sophisticated data analysis, the current study offers insight into the key factors influencing the ozone changes in the vicinity of power plants. Ground ozone (O₃) and its precursor variables carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO₂), Sulphur dioxide (SO₂), benzene, toluene, ethyl-benzene and xylene (BTEX) along with the particulate matter of size less than 10 and 2.5 micron (PM₁₀ and PM_2.5) and meteorological variables have been studied at a residential site near the coal-fired power plant in the two cities; Chandrapur and Nagpur during 2016–2019. O₃ is observed to be not correlated significantly (r<0.16 and <0.1 in Nagpur and Chandrapur, respectively) with any of its precursor variables in two cities. On a finer time scale, however, an association of O₃ with CO, NO, NO₂ and BTEX suggested that the O₃ formation mechanism is driven by volatile organic compounds (VOCs) (mainly BTEX), CO and NO_x. On the coarser scale, however, seasonality and other factors have distorted the correlation. Random forest model with O₃ concentration as the response variable and NO₂, NO, SO₂, CO, BTEX, PM₁₀ and PM_2.5 as independent variables suggested that PM₁₀, NO, CO and solar radiation are highly important variables governing the O₃ dynamics in Chandrapur. In Nagpur, wind direction, relative humidity, temperature, toluene and NO₂ are more important. Qualitative analysis to assess the contribution of emission sources suggested the influence of traffic emissions in Nagpur and the dominance of non-traffic related emissions, mainly power plant and mining activities in Chandrapur. The hazard quotient is observed to be >1 in both cities suggesting a health hazard to the residents living in the area.

To improve the effect of MgO–SiO₂ binders solidifying municipal solid waste incineration fly ash (MSWI FA), MSWI FA solidified bodies with five MgO/SiO₂ ratios (0.41 ~ 3.77) were investigated. The leaching behavior of solidified bodies was evaluated by leaching toxicity tests and pH-dependent experiments. In addition, hydration products in solidified bodies were analyzed by thermodynamic modeling and microstructure characterizations. The results showed that the variation in the MgO/SiO₂ ratio had a significant effect on the leaching toxicity of the solidified bodies, because it affected the leachate pH and the composition of the hydration products of the solidified bodies. The acid and alkali resistance of the MSWI FA was enhanced through solidification with MgO–SiO₂ binders. MgO can improve the alkalinity of the solidified bodies and facilitate the chemical precipitation of heavy metals. Moreover, silica fume, an industrial waste, can serve as a cost-effective measure. Overall, MgO–SiO₂ binders demonstrated great potential as promising candidates for encapsulating MSWI FA.

The bottom ash is increasingly used as a substitute aggregate material in road construction in China, and road salting is the major salt source in groundwater. Continuous rainfall releases soluble salts from the bottom ash subgrade into the surrounding soil and groundwater, resulting in potential hazards. Different methods were employed to simulate and collect runoff water during rainfall events, including batch leaching test, dynamic leaching test and constant head test, to assess environmental impact of bottom ash as road basement materials under continuous rainfall conditions. This study simulated the seepage of bottom ash backfill roads under different rainfall intensities, rainfall times, and rainfall pH values. A comprehensive sampling and laboratory testing program was undertaken to characterize the environmental impact of soluble salts from bottom ash. The obtained results reveal that the leaching concentrations of Cl⁻ and SO₄²⁻ exceed the limit specified in the class V standard of surface water, which are 2.06–2.17 times and 1.08–1.25 times, respectively. By examining the long-term environmental influence under the condition of continuous rainfall, the leaching of Cl⁻ mainly occurs in the early leaching stage, and the maximum leaching concentration reaches 19,700 mg/L. The release concentration of Cl⁻ begins to be lower than the class V standard of surface water when continuous rainfall approaches the total rainfall for 13 months. The cumulative release of Cl⁻ in the bottom ash is 2.8–5.4 mg/g. Both rainfall intensity and rain pH affect the release of Cl⁻. The obtained results derived from the constant head tests indicate that stagnant water caused by rainfall deteriorates the release of soluble salt into the groundwater in only 1 day, especially at the early stage of 12 h. This work provides some basic information about how to minimize damage to the surrounding environment caused by the leaching of salt in bottom ash.