Waste Disposal & Sustainable Energy最新文献

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.

Microbial electrolysis cell (MEC) is a potential technology to meet the increasing interest in finding new sources of energy that will not harm the environment. MEC is an alternative energy conversion technology for the production of biofuels. It is possible to produce hydrogen by fermenting biogenous wastes with hydrogen-producing bacteria. This study investigated the biohydrogen production from co-substrates using electrogenic bacteria such as Escherichia coli, Salmonella bongori, and Shewanella oneidensis in pure culture and as a co-culture, which has the potential to be used as co-substrate in MECs. Briefly, 150 mL working-volume reactors were constructed for batch biohydrogen production. The hydrogen production rate (HPR) from the co-substrate was maximum at a ratio of 75:25 g/L with a co-culture of 2.35 mL/(L h). Fabricated a single-chamber membrane-free microelectrolysis cell to evaluate the power density, current density, voltage, HPR, chemical oxygen demand (COD) removal efficiency and Columbic efficiency. Scanning electron microscope (SEM) imaging confirmed the binding of electrogenic bacteria to anode and cathode. The efficiency of electrical conductivity of MEC was analyzed by three different electrodes, namely, nickel, copper and aluminum. The HPR was high using nickel when compared to the other two electrodes. The HPR of a single chamber using a nickel electrode was 2.8 HPR ml/L H₂ d⁻¹ and provided a power density of 17.7 mW/m² at pH 7. This study suggests that the nickel cathode in a single chamber could be a promising sustainable source for stable power generation.

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Electrical and electronic waste (e-waste) has become a global crisis. Managing this ever-growing problem has become very critical and yet challenging, especially in the South Asian region; otherwise, it may undermine the sustainability of development and growth of numerous industries. Hence, to explore the current context of e-waste management, recycling, and strategies in Sri Lanka, we conducted a systematic literature review process using peer-reviewed research articles retrieved from Google Scholar Database. We searched for articles containing keywords such as “e-waste”, “management strategies and recycling”, and “Sri Lanka”. We screened out papers (n = 20) selected from papers (n = 327) initially retrieved over a 17 period of time (2005–2022). The analysis of the screened articles showed that the main challenges to successful e-waste management were a lack of management strategies, policies, and inadequate recycling practices as well as identifying the potential and opportunities to actively enhance the comprehensive awareness, collection, storage, proper disposal, and other e-waste management steps in Sri Lanka. Further, the study identified technological, financial, socio-economic, and institutional sectors as fundamental sectors to formulate a strategic plan for e-waste management. Also, the study suggests that enacting laws to practice and adopt e-waste management, establishing central command and management institutes to control all e-waste management bodies, providing financial assistance to informal e-waste collectors and recyclers, and introducing e-waste management to school curricula are some of the possible actions that can be taken along with enhancing the awareness of  e-waste management.

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Biobed is a smart bioremediation system used to treat point-source pesticide contamination. Biomixture is the main component of biobeds, and pesticide dissipation is affected by its composition. This study aimed to compare the effectiveness of compost-based (C) versus peat-moss-based (P) biomixtures of biobeds on tested pesticide dissipation. Three concentrations (25, 50, and 75 mg/kg) of chlorpyrifos, pendimethalin, and thiophanate methyl were added separately and as a mix to both biomixtures C and P. Our data showed the effect of biomixture type on the dissipation of the tested pesticides. For chlorpyrifos, its dissipation rate in biomixture P was more rapid than that in biomixture C. This result was confirmed by the mineralization kinetic experiment, since 25% of the initial ¹⁴C-chlorpyrifos concentration accumulated in the form ¹⁴CO₂ in biomixture P compared to only 14% in biomixture C. In addition, the chlorpyrifos dissipation rate was influenced by the initial concentration when applied individually in biomixture P. In contrast, biomixture C was more effective at pendimethalin dissipation than biomixture P, since >76% of pendimethalin was dissipated in biomixture C versus 67% in biomixture P at the same incubation time. For thiophanate-methyl, the abilities of both biomixtures C and P were similar and less efficient than those of the other tested pesticides. The addition of the three tested pesticides to biomixture C only had a positive effect on both chlorpyrifos and thiophanate-methyl dissipation, while pendimethalin dissipation was similar when applied separately or as a mix. Microbial activity was stimulated by the addition of separately or mixed pesticides to biomixtures C and P as measured by dehydrogenase activity.

The waste-to-energy (WTE) technologies are now recovering energy and materials from over 300 million tonnes of municipal solid wastes worldwide. Extensive studies have investigated substituting natural construction materials with WTE residues to relieve the environmental cost of natural resource depletion. This study examined the beneficial uses of WTE residues in civil engineering applications and the corresponding environmental standards in Europe, the U.S., and China. This review presents the opportunities and challenges for current technical approaches and the environmental standards to be met to stabilize WTE residues. The principal characteristics of WTE residues (bottom ash and fly ash) and the possible solutions for their beneficial use in developed and developing countries are summarized. The leaching procedures and environmental standards for pH, heavy metals, and polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) are compared. The current practice and engineering properties of materials using WTE residues, including mixtures with stone aggregate or sand, cement-based or hot-mix asphalt concrete (pavement), fill material in the embankments, substitute of Portland cement or clinker production, and ceramic-based materials (bricks and lightweight aggregate) are comprehensively reviewed.

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Excessive construction activities generate huge quantities of waste that are disposed of in nearby sites, leading to environmental degradation. Recycling the concrete fractions of construction wastes for their utilization as aggregates has been predominant among industrialists and researchers in recent years. However, the smearance of cement mortar on the recycled aggregates affects the concrete properties. Fewer treatments were developed to remove the weak cement mortar or seal the micro-pores on the adhered cement mortar of recycled aggregates. This paper investigates the comparative efficiency of acid and carbonation treatment on recycled coarse aggregate (RCA) properties and its behaviour on recycled aggregate concrete (RAC). The RCA was treated with HCl acid at 0.1 mol/L, 0.5 mol/L, and 0.8 mol/L and CO₂ at 0.1 bar, 0.2 bar, and 0.4 bar and tested for their physical properties, and the concrete mixtures with treated recycled aggregates were tested for fresh and hardened properties. It could be observed that the properties of RAC were affected owing to the smearance of weak mortar, whereas for the concrete with carbonated (RACc) and chemically treated aggregates (RACa), the concrete properties tended to improve. The strength of RAC was 28.59% less than that of normal aggregate concrete (NAC), whereas the strength of RACc and RACa was enhanced by 16.44% and 9.7% compared to that of RAC at 28 days. The water absorption of RAC was 47.51% more than that of NAC, whereas the water absorption of RACa and RACc was 28.67% and 33.75% lesser than RAC. Pre-soaking the RCA with acids removes the adhered mortar due to its acidic activity. In contrast, in carbonation, the CO₂ reacts with the Ca(OH)₂ on the cement mortar to form CaCO_3, filling the micro-cracks in the cement mortar on the RCA.

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Activated carbon (AC) has attracted tremendous research interest as an electrode material for supercapacitors owing to its high specific surface area, high porosity, and low cost. However, AC-based supercapacitors suffer from limited rate performance and low power density, which mainly arise from their inherently low electrical conductivity and sluggish ion dynamics in the micropores. Here, we propose a simple yet effective strategy to address the aforementioned issue by nitrogen/fluorine doping and enlarging the micropore size. During the treatment, the decomposition products of NH₄F react with the carbon atoms to dope the AC with nitrogen/fluorine and simultaneously enlarge the pores by etching. The treated AC shows a higher specific surface area of 1826 m² g⁻¹ (by ~ 15%), more micropores with a diameter around 0.93 nm (by ~ 33%), better wettability (contact angle decreased from 120° to 45°), and excellent electrical conductivity (96 S m⁻¹) compared with untreated AC (39 S m⁻¹). The as-fabricated supercapacitors demonstrate excellent specific capacitance (26 F g⁻¹ at 1 A g⁻¹), significantly reduced electrical resistance (by ~ 50%), and improved rate performance (from 46.21 to 64.39% at current densities of 1 to 20 A g⁻¹). Moreover, the treated AC-based supercapacitor achieves a maximum energy density of 25 Wh kg⁻¹ at 1000 W kg⁻¹ and a maximum power density of 10,875 W kg⁻¹ at 15 Wh kg⁻¹, which clearly outperforms pristine AC-based supercapacitors. This synergistic treatment strategy provides an effective way to improve the rate performance and power density of AC-based supercapacitors.