Waste Disposal & Sustainable Energy最新文献

In this study, Mn-based bimetallic oxide catalysts were synthesized via the solvothermal method. Different metals (Ce, Co and Fe) exhibited a great impact on the physicochemical properties of catalysts, resulting in different catalytic activities for the simultaneous removal of 1,2-dichlorobenzene (1,2-DCB) and furan, as a model of polychlorinated dibenzodioxins and dibenzo-furans (PCDD/Fs). Fe–MnOx presented the best catalytic activity, with a removal efficiency of 62% for 1,2-DCB and 100% for furan at 240 °C. Several analytical techniques were employed, namely, Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), H₂ temperature-programmed reduction (H₂-TPR), and ammonia temperature programmed desorption (NH₃-TPD). Compared with pure MnOx catalysts, Fe–MnOx shows a higher specific surface area of 117.9 m²/g. SEM observations showed flower-like nanosheet structures for Fe–MnOx. XPS analysis indicated that Mn⁴⁺/Mn³⁺ and active oxygen play the key roles in the catalytic oxidation of 1,2-DCB and furan. The catalytic activity, selectivity and stability of Mn-based bimetallic oxide catalysts for the oxidation of 1,2-DCB and furan were tested. Competition exists between 1,2-DCB and furan such that the adsorption of furan occurs prior to 1,2-DCB.

The vastly increasing generation of plastic packaging waste has outgrown the infrastructure capacity to manage this waste effectively, resulting in critical aquatic and terrestrial pollution. In 1994, the European Commission implemented the Packaging and Packaging Waste Directive 94/62/EC, responding to growing concerns regarding the environmental impact of packaging and safe waste management. This study analyses how Germany, Spain, France, Italy, and Poland—the five most populous countries in the EU (European Union)—manage their plastic packaging waste, and evaluates their established Extended Producer Responsibility (EPR) schemes, which are mandatory for all EU Member States by the end of 2024. This research shows that EPR schemes improve the financial and operational viability of plastic waste management in the scope countries, resulting in higher collection and recycling rates. Take-back requirements can incentivise producers to put less plastic packaging on the market, and advanced disposal fees can encourage eco-design. The Producer Responsibility Organisation plays a crucial role in both producer and consumer awareness, and in ensuring that plastic waste is safely managed. However, the local recycling infrastructure of 6.5 Mt in 2018 is a major barrier to reaching 50% recycling of plastic packaging in the EU by 2025. The European recycling capacity only covered about 23% of the cumulative post-consumer plastic waste generation, delaying the transition to the EU circular plastic economy. The recycling capacity has increased by 3 Mt between 2018 and 2020 and needs to continue its rapid expansion to become autonomous in reaching the recycling targets.

Phosphorus (P) recovery from incinerated sewage sludge ash (ISSA) has been extensively investigated, but insufficient research has been conducted to evaluate the effect of different kinds of recovered phosphate fertilizers (RPFs) on plant growth with respect to the P and heavy metal contents of RPFs. In this study, three kinds of RPFs, precipitated calcium phosphate fertilizer (CaP), struvite phosphate fertilizer (SP), and P-loaded biochar (BP), produced from ISSA were characterized, and their agronomic effectiveness was verified by hydroponic and soil cultivation. In addition to the three kinds of RPFs, a control group (mono-phosphate fertilizer in hydroponic group/compound fertilizer in soil cultivation group) and a blank control group (BC, with zero P) were tested on choy sum and ryegrass at the same time. SP has the highest P purity (76.0% of struvite) while the BP has the most complex P species (P was co-exist with Fe, Al, and Mg). Plant growth results showed that the RPFs greatly facilitated plant growth and demonstrated superior/comparable effects to those of control group. In hydroponics testing, SP showed the best effect (shoot length of 17.0 cm, chlorophyll content of 2.05 mg/g) due to the Mg involved and the high P purity of SP, while BP performed the best (shoot length of 13.7 cm, chlorophyll content of 2.42 mg/g) in the soil testing system among all of the groups because of the additional nutritional elements and the high P availability of BP. Additionally, the accumulation of heavy metals in the plants under all conditions did not exceed the limits stipulated in the regulations. These results indicate that recovering P from ISSA is an attractive technology to produce P fertilizers, which can alleviate both the scarcity of phosphate resources and the burden of ISSA management.

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Municipal solid waste incineration (MSWI) fly ash (FA) is classified as hazardous waste, which requires additional treatment before disposal or further utilization. Stabilization/solidification (S/S) is regarded as a low-cost and high-efficient method for MSWI FA treatment. “Low-carbon S/S” has captured extensive interest in recent years, which could treat hazardous wastes and enable resource recycling in a sustainable way. This article introduced the state-of-art low-carbon S/S strategies for MSWI FA treatment. The immobilization mechanisms of pollutants in various matrices were also discussed. Prospects were raised to foster the actualization of sustainable management of MSWI FA.

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Ammonia (NH₃) synthesis via electrocatalytic nitrogen reduction generally suffers from low NH₃ yield and faradaic efficiency. Compared with activating stable, low-solubility N₂, the electrochemical conversion of nitrates to ammonia provides a more reasonable route for NH₃ production. Herein, we introduce Ar-plasma to enhance the interaction between copper-nickel alloys and carbon substrate to improve the performance of NH₃ production. The NH₃ faradaic efficiency from nitrate is nearly 100% and the yield rate is over 6000 ({mathrm{mu g}}_{{mathrm{NH}}_{3}}{mathrm{cm}}^{-2}{mathrm{h}}^{-1}). DFT (density functional theory) calculation reveals the high performance of Cu₅₀Ni₅₀ originates from the lower energy barrier on the reaction path and the closer position to the Fermi level of the d-band center. This work offers a promising strategy for plasma-modified electrocatalyst to promote ammonia synthesis via nitrate reduction.

In this study, coal slime was mainly utilized to conduct experiments on a 30 kW preheating combustion test rig to analyze the conversion pathway of sulfur during the experiment, aiming at reducing slime pollution, controlling sulfur emission reasonably, and providing theoretical support for the preheating combustion technology. The results showed that after the coal slime was preheated, a large number of elements were released. The maximum release rates for H and S were 94.0% and 73.3%, respectively. The released S was converted into the sulfur-containing gases like H₂S, COS, CS₂, and the rest existed in the solid in the five forms of mercaptan, thiophene, sulfoxide, sulfone, and sulfate. Besides, during the combustion process, the gas was oxidized continuously and finally converted into SO₂, leaving only the sulfate in the fly ash. In the preheating combustion process, 26.7% of the S was released from the coal, 73.3% of the S was retained in the semi-coke, and the final SO₂ emission concentration of combustion was 959 ppm.

Incomprehension concerning heavy metal containing finished solid leather wastes leads to environmental pollution. Conversion of these solid leather waste into energy and resource efficient products proves to be challenging. However, leather microfibres (LMF) were isolated from these heavy metal containing finished solid leather wastes. These heavy metal contain LMF further processed into metal reduction LMF. The metal reduction LMF were investigated for their heavy metal removal efficiency and toxicity analysis. The Cr (III) and Cr (VI) content of LMF was <1000 µg/mL and <800 µg/mL, respectively. Toxicity estimation was proved that the LMF had less than 1%. The study attempt to prepare reconstituted fibric materials (RFM) from metal reduction LMF and cellulose nanofibres (CNF). RFM were characterized for their physicochemical and mechanical properties. Hence, the study has proved a novel concept of RFM production which is recyclable, environmental friendly and cost effective.

Decentralized solid-waste incinerators (DSWIs) have certain advantages for waste disposal from villages and towns. However, the incineration condition is always affected by the distribution of temperature and oxygen concentration, which causes difficulties in operation and maintenance. In this study, the temperature and oxygen concentration distribution of DSWI were characterized using different air flow rates and bottom ash volumes. The results showed that the adjustment of air flow has no significant influence on the heating process of the DSWI, while the retention of bottom ash did affect the temperature and oxygen concentration fields in the furnace. When the air flow rate was increased without the retention of bottom ash, 99% of the furnace volume temperature was observed between 780 °C and 800 °C. However, once the bottom ash was retained, the whole furnace temperature was steadily maintained between 800 °C and 850 °C. When the air flow rate was increased without bottom ash, the highest furnace volume percentage of oxygen concentrations higher than 3% maxed out at 11% volume, while it could reach 100% when bottom ash remained. The distribution of the temperature and oxygen concentration in the DSWI characterized by this research provides strong support for the operation and management of such systems.

China is the largest producer and consumer of calcium carbide in the world. The calcium carbide industry is an indispensable industry to support the basic life of people. The huge production capacity of calcium carbide is accompanied by a large number of solid waste carbide slag. Due to the immature treatment technology of carbide slag, a large number of carbide slag are stacked on-site, resulting in land occupation, air-drying, easy take-off ash, and pollution of the environment and water resources. In China, calcium carbide is mainly used to produce acetylene and further utilized, 80% of which is used to produce polyvinyl chloride (PVC). A large amount of carbide slag is not used, while only a small part is used in the traditional building materials industry, flue gas desulfurization, sewage treatment, etc., however, the economic benefits are poor. Therefore, converting the solid waste carbide slag produced by the calcium carbide industry into high value-added CaCO₃, CaCl₂, CaSO₄ whiskers, etc. has become a potential way to expand the development field of the calcium carbide industry and is environmentally friendly. This paper focuses on summarizing the traditional and emerging high value-added utilization technologies of carbide slag, and then introduces the application research of carbide slag in carbon emission reduction. Finally, the defects of these technologies are summarized and further research directions are prospected. This study provides basic guidance for the diversified development of efficient resource utilization of carbide slag.

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Diversified development of calcium carbide industry, resource utilization of solid waste carbide slag and its application of carbon emission reduction have been fully reviewed.

Appropriate solid waste management (SWM) strategies are necessary to avoid severe environmental and sanitary impacts, especially in low-income countries. Such strategies are most likely to succeed whether implementing actors are supported by scientific research. In this paper, the results of a collaboration between local authorities and researchers are presented and discussed that are the assessment of waste generation in the city of Quelimane (Mozambique), integrating existing and field-collected data and the design of a small-scale center for plastic sorting to complement the SWM system of the city. The center is expected to receive about 0.3–0.4 t/day of plastic waste (5%–7% of the overall amount of plastic waste daily produced in Quelimane). As long-term sustainability represents a typical issue, simplicity of operation was a leading principle in the design of the center; moreover, the design included a treatment plant (WWTP) for generated wastewater, whose management is usually neglected in such interventions. Among others, natural wastewater treatment (constructed wetlands) has been chosen for its affordability. Noteworthy, the so-conceived WWTP appears as a novelty in the scientific literature associated with small-scale plastic sorting plants. The system is designed to treat an average flow of 6 m³/day and consisted of a septic tank followed by a subsurface flow constructed wetland. Overall, the COD (chemical oxygen demand) and TSS (total suspended solids) removal higher than 80% and 90% were estimated, respectively. Based on this work, both the center and the WWTP were successfully realized, which are waiting to become operational. In the authors’ opinion, the implemented procedure could become a reference for broader investigations and surveys.