Waste Disposal & Sustainable Energy最新文献

Population growth, waste generation, and massive waste mismanagement have led to environmental catastrophe. Management of municipal solid waste (MSW) requires an efficient and sustainable integrated system. The integrated thermal processing of MSW is one of the best waste management techniques. In this study, energy analysis of MSW is carried out based on the material and energy balance of 2000 kg wet MSW, which contains 50% leachate. Once the leachate is removed, the dry MSW is sent for carbon content enhancement in carbonization to produce MSW-based char. Thereafter, the combustion of MSW-based char provided high heat and syngas to be used in a hydrothermal process for MSW leachate treatment. The result shows that the char fuel of MSW produces a sufficient amount of energy, 13501.29 MJ (84.55%), in the form of synthetic gas by-product, which has a big potential as an energy source. The novelty of the proposed integrated thermal system is to produce 84.55% synthetic gas by-product, which is used for electricity production, cooking, food, and heat energy for industrial purposes. The proposed applications of this paper offer insightful information for policymaking regarding novel MSW techniques, which are economical, energy-efficient, and environmentally friendly. Thus, it increases the effectiveness of MSW utilization.

Graphical abstract

Food waste generation is a pressing issue that requires urgent attention and concerted efforts worldwide. The staggering amount of food wasted each year not only wastes valuable resources but also exacerbates environmental, economic, and social challenges. Food Waste Management (FWM) consists of a complex array of criteria and sub-criteria, and treatments which seems interdependent. There is a need to evaluate the FWM with the help of important criteria and sub-criteria and treatments to address this challenge. In this study, we identified four important criteria, 21 sub-criteria, and four alternatives of FWM for the case of Malaysia using the integrated approach of literature review and expert opinions. Further, we employed the approach of Modified Fuzzy Improved Analytical Hierarchy Process (IAHP) to corroborate the interrelationships among the identified criteria and sub-criteria, and their associated treatments. This study undertakes linear normalization methods to transform data into comparable numerical values and the Geometric Mean method to handle uncertainty in human judgments. Moreover, the Centroid method is employed to convert fuzzy weights into crisp sets for ease of interpretation. The results indicate that environmental is the most essential criterion, followed by social, economic, and technical. In addition, air and water pollution is identified as the most critical sub-criteria. Black Soldier Fly is discovered as the most sustainable FWM treatment, since it performs the best while meeting all the criteria and sub-criteria assessed. Sensitivity analysis demonstrates that the outputs from the proposed method are robust and reliable. The finding suggests a proper and robust approach to help decision-makers select suitable FWM treatments to tackle various criteria and alternatives especially when handling inconsistent and uncertain judgments during evaluation.

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) have attracted widespread concern due to their high toxicity, and their difficult manipulation in laboratories has made the research process tough. Thus, in our work, furan is selected as the model compound owing to the same structure of a central oxygenate ring. Although catalytic oxidation is regarded as an effective and applicable method for the abatement of PCDD/Fs, the synthesis of low-temperature catalysts is still a challenging problem in practical applications. Considering this situation, we prepared a novel V₂O₅/TiO₂ catalyst modified with N-doped hierarchical porous carbon (NHPC) via a wet impregnation method. The V/T-1%NHPC catalyst could achieve expectant low-temperature performances with 50% furan conversion at 150 °C and a complete conversion at 200 °C, which decreased 23 °C and 40 °C compared to the V/T catalyst respectively. Moreover, the addition of NHPC presented lifting chemical stability during long-time test. The addition of NHPC in V/T catalysts decreased the formation of crystalline V₂O₅ and increased the percentages of V⁵⁺ and O_lat, which improved the utilization of vanadium ions and the catalytic activity. Simultaneously, the higher binding energy shift of O_lat implied more reaction possibility with other oxidise reactants. Importantly, this work proved the lifting catalytic activity by the interaction between catalysts and NHPC, and proposed the promoting effects of the N element. The results showed that the content of the pyridinic N and graphitic N in NHPC changed after combining with V/T catalyst, which played crucial roles in the excellent catalytic performance. Overall, this work provides comprehensive research of the V/T-1%NHPC catalyst toward furan oxidation at low temperature and explain the effects of N-doped biomass carbon in catalytic activity clearly, which gave a new thought to design low-temperature catalysts in PCDD/Fs degradation. Besides, the internal functional mechanisms of N species are worth further exploration in future studies.

Graphical abstract

Five common single plastics and nine different household, commercial and industrial waste plastics were processed using a three-stage (i) pyrolysis, (ii) catalytic steam reforming and (iii) water gas shift reaction system to produce hydrogen. Pyrolysis of plastics produces a range of different hydrocarbon species which are subsequently catalytically steam reformed to produce H₂ and CO and then undergo water gas shift reaction to produce further H₂. The process mimics the commercial process for hydrogen production from natural gas. Processing of the single polyalkene plastics (high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene (PP)) produced similar H₂ yields between 115 mmol and 120 mmol per gram plastic. Even though PS produced an aromatic product slate from the pyrolysis stage, further stages of reforming and water gas shift reaction produced a gas yield and composition similar to that of the polyalkene plastics (115 mmol H₂ per gram plastic). PET gave significantly lower H₂ yield (41 mmol per gram plastic) due to the formation of mainly CO, CO₂ and organic acids from the pyrolysis stage which were not conducive to further reforming and water gas shift reaction. A mixture of the single plastics typical of that found in municipal solid waste produced a H₂ yield of 102 mmol per gram plastic. Knowing the gas yields and composition from the single plastics enabled an estimation of the yields from a simulated waste plastic mixture and a ‘real-world’ waste plastic mixture to be determined. The different household, commercial and industrial waste plastic mixtures produced H₂ yields between 70 mmol and 107 mmol per gram plastic. The H₂ yield and gas composition from the single waste plastics gave an indication of the type of plastics in the mixed waste plastic samples.

Graphical abstract

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.

Graphical abstract

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.

Graphical abstract

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.

Graphical abstract

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.

Graphical abstract

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.

Graphical abstract

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.