Utilization Of Waste Resources Research Articles

Adsorption characteristics and mechanisms of bisphenol A on novel nitrogen-modified biochar derived from waste masks and biomass.

Resource utilization of waste masks has become an urgent scientific issue. In this work, with sustainably, waste masks and biomass were co-pyrolysis with oxygen limitation to prepare mask-based biochar (MB). Then, urea was introduced to prepare novel nitrogen modified mask-based biochar (NMB) via a one-step hydrothermal synthesis method. The adsorption characteristics of NMB on the emerging environmental pollutant, bisphenol A (BPA), were evaluated via batch adsorption tests. Moreover, the physicochemical properties of the materials were characterized with various advanced techniques. Also, the roles of waste masks and nitrogen modification were explored. The adsorption mechanisms of NMB on BPA were revealed as well as the performance differences between different adsorbents. The results showed that waste masks participated in thermochemical reactions, shaped the microsphere structure of biochar, and increased the types of surface functional groups. The nitrogen modification enriched the surface elemental composition and activated the specific surface area via the mesopore. These would enhance the adsorption performance. The maximum adsorption of BPA by NMB was 62.63mg·g-1, which was approximately 2.35-5.58 times higher than that of the control materials. Temkin model and pseudo-second-order model optimally simulate the isothermal and kinetic adsorption, respectively. The adsorption mechanisms are jointly by physical and chemical adsorption, which mainly includes π-π interaction, hydrogen bonding, intraparticle diffusion, surface adsorption, and ion exchange. After discussion and evaluation, NMB has lower preparation process cost (7.21 USD·kg-1) and safety, with potential for environmental applications. This study aims to expand new ideas for the comprehensive utilization of waste masks and the preparation of eco-friendly materials. Moreover, it provides a theoretical basis for the removal of BPA.

Selective hydrolysis of traditional Chinese medicine residue into reducing sugars catalysed by sulfonated carbon catalyst and application of hydrolysate

The conversion of waste into high-value products has long been a focus point of research in green and sustainable chemistry. In this study, a novel value-adding strategy was devised to not only facilitate the resource utilization of biomass waste like Chinese medicine residue (CMR) and pomelo peel but also contribute to the advancement of microalgae cultivation. Sulfonated biochar PP-700-S was synthesized from pomelo peel waste, and its morphology and structural characteristics were analyzed. An effective method for the hydrolysis of CMR using PP-700-S as a catalyst in the aqueous phase was then explored, with a thorough investigation of the process and key influencing factors. Under the reaction conditions of 130 °C, 24 h, 20 mL H2O, CMR: PP-700-S = 1: 1, a 51.87 % yield of reducing sugars was directly obtained from the CMR, with PP-700-S exhibiting the selectivity of glucose production. Subsequently, the hydrolysate (HL-CMR) was utilized as a growth medium for microalgae, revealing that the presence of HL-CMR enhanced the nutrient balance in the medium, creating a more conducive environment for microalgae growth. Overall, this study presents a sustainable and efficient pathway for the utilization of lignocellulosic waste, facilitating the conversion of waste into higher-value products and contributing to the development of a green and sustainable science.

Co-pyrolysis of wheat straw with polyester-based polyurethane for nitrogenous compounds: Pyrolysis kinetic properties and synergistic effects

To re-utilize agricultural waste straw and waste plastic, the co-pyrolysis process of wheat straw (WS) and high-nitrogen polymer polyester-based polyurethane (PU) and the synergistic effects were studied. The results showed that PU facilitated pyrolysis to occur at lower temperatures. The effective apparent activation energies (Eα) of different samples were calculated at different conversion rates with three methods (Kissinger, KAS and Starink). It was found that PU decreased the Eα values and enthalpy change of WS and increased the reactivity. Both ΔG and ΔS results indicate that a heating rate of 5 ℃/min is more favorable for co-pyrolysis. PU greatly promoted the production of pyrolysis oil. Co-pyrolysis oil doped with 75 % PU gave the highest yield of 77 wt%. Co-pyrolysis effectively suppressed the production of acids, aldehydes, and phenols in pyrolysis oils. It increased the levels of alcohols and ketones, improving the pyrolysis oil's stability and calorific value. α, β-unsaturated aldehydes produced by WS during pyrolysis reacted with hydrazine derivatives produced by PU pyrolysis to produce pyrazole compounds after dehydration. In the co-pyrolysis of 50 % doped PU, the reaction of methyl and methylene produced by WS with amines (-NH2) produced by the pyrolysis of PU promotes the production of trimethylamine. The yield of amines in the nitrogenous compounds reached a maximum at this time. PU increased the yield of nitrogenous compounds and their variety. It favored the output of high-value chemicals. FT-IR analyses of pyrolytic charcoal showed that the addition of PU promoted the cleavage of WS and the dehydration and decarboxylation reactions of C-O and C-O-C. Finally, synergistic effects and nitrogen conversion mechanisms in the co-pyrolysis process are proposed. This work provided a theoretical basis for the resource utilization of WS waste and PU waste.

Risk of hydrogen sulfide pollution from pressure release resulting from landfill mining

Landfill mining (LFM) has gained widespread recognition due to its benefits in terms of resource utilization of landfill waste and reuse of landfill sites. However, it is important to thoroughly assess the associated environmental risks. This study simulated the pressure release induced from LFM in small-scale batch anaerobic reactors subject to different initial pressures (0.2–0.6 MPa). The potential risk of hydrogen sulfide (H2S) pollution resulting from pressure release caused by LFM was investigated. The results demonstrated that the concentration of H2S significantly increased following the simulated pressure treatments. At the low (25 °C) and high (50 °C) temperatures tested, the peak H2S concentration reached 19366 and 24794 mg·m−3, respectively. Both of these concentrations were observed under highest initial pressure condition (0.6 MPa). However, the duration of H2S release was remarkably longer (>90 days) at the low temperature tested. Microbial diversity analysis results revealed that, at tested low temperature, the sulfate-reducing bacteria (SRB) communities of various pressure-bearing environments became phylogenetically similar following the pressure releases. In contrast, at the high temperature tested, specific SRB genera (Desulfitibacter and Candidatus Desulforudis) showed further enrichment. Moreover, the intensified sulfate reduction activity following pressure release was attributed to the enrichment of specific SRBs, including Desulfovibrio (ASV585 and ASV1417), Desulfofarcimen (ASV343), Candidatus Desulforudis (ASV24), and Desulfohalotomaculum (ASV506 and ASV2530). These results indicate that the pressure release associated with LFM significantly increases the amount of H2S released from landfills, and the SRB communities have different response mechanisms to pressure release at different temperature conditions. This study highlights the importance of considering the potential secondary environmental risks associated with LFM.

Evolutionary Game Analysis for Promoting the Realization of Construction Waste Recycling and Resource Utilization: Based on a Multi-Agent Collaboration Perspective

Evolutionary Game Analysis for Promoting the Realization of Construction Waste Recycling and Resource Utilization: Based on a Multi-Agent Collaboration Perspective

Trilogy of comprehensive treatment of kitchen waste by bacteria-microalgae-fungi combined system: Pretreatment, water purification and resource utilization, and biomass harvesting

Given its profound disservice, a bacteria-microalgae-fungi combined system was designed to treat kitchen waste. Firstly, a new type of microbial agent homemade compound microorganisms (HCM) (composed of Serratia marcescens, Bacillus subtilis and other 11 strains) with relatively high bio-security were developed for pretreating kitchen waste, and HCM efficiently degraded 85.2 % cellulose, 94.3 % starch, and 59.0 % oil. HCM also accomplished brilliantly the initial nutrients purification and liquefaction conversion of kitchen waste. Under mono-culture mode (fungi and microalgae were inoculated separately in the pre - and post-stages) and co-culture mode (fungi and microalgae were inoculated simultaneously in the early stage), microalgae-fungi consortia were then applied for further water purification and resource utilization of kitchen waste liquefied liquid (KWLL) produced in the pretreatment stage. Two kinds of microalgae-fungi consortia (Chlorella sp. HQ and Chlorella sp. MHQ2 form consortia with pellet-forming fungi Aspergillus niger HW8–1, respectively) removed 79.5–83.0 % chemical oxygen demand (COD), 44.0–56.5 % total nitrogen (TN), 90.3–96.4 % total phosphorus (TP), and 64.9–71.0 % NH4+-N of KWLL. What's more, the microalgae-fungi consortia constructed in this study accumulated abundant high-value substances at the same time of efficiently purifying KWLL. Finally, in the biomass harvesting stage, pellet-forming fungi efficiently harvested 81.9–82.1 % of microalgal biomass in a low-cost manner through exopolysaccharides adhesion, surface proteins interaction and charge neutralization. Compared with conventional microalgae-bacteria symbiosis system, the constructed bacteria-microalgae-fungi new-type combined system achieves the triple purpose of efficient purification, resource utilization, and biomass recovery on raw kitchen waste through the trilogy strategy, providing momentous technical references and more treatment systems selection for future kitchen waste treatment.

Biomass-tar-derived oxygen-enriched porous carbon as a high-performance carbon electrode material for double electric layer and zinc-ion hybrid supercapacitor

Carbon-based capacitor electrodes have the advantages of high capacitance value, superior recyclability, and inexpensive raw materials, which fuel the application of capacitors in large-scale energy storage. Biomass tar is a hazardous waste that can be recycled as a low-cost carbon electrode precursor for capacitors, due to its retaining biomass-based heteroatom. In this study, hierarchically porous carbon with cross-linked structure was fabricated by using a nano-Al2O3 template combined with the KOH activation technique, in which the γ-Al2O3 has a size of only 10 nm with high specific surface area, thus optimizing the pore structure of the carbon material. The resulting optimal material, BTC-0.2-2-800, contains abundant pore structure and extremely high oxygen content, delivers low resistance and excellent rate performance with high specific capacitance of 292.1 F g−1 and 221.7 F g−1 at 1 A g−1 and 20 A g−1, respectively, in double electric layer supercapacitors (EDLCs). Besides, no significant capacity degradation after 10,000 charging and discharging cycles at 10 A g−1 was found. The two-electrode device prepared using Na2SO4 electrolyte achieves a high energy density of 43.18 Wh kg−1 at the power density of 1000 W kg−1, which can light up a 2 V LED lamp. Moreover, Zinc-ion hybrid supercapacitor (ZIHSC) fabricated with BTC-0.2-2-800 carbon electrode accounts for the energy densities of 69.82 Wh kg−1 and 49.39 Wh kg−1 at the power densities of 40 W kg−1 and 400 W kg−1, respectively. This study reveals the great potential of biomass-tar-derived carbon as a high-performance electrode material, which may provide an opportunities for the resource utilization of hazardous wastes.

Study on the micro-rheological properties of fly ash-based cement mortar

Aiming at the shortcomings of poor rheological properties and low strength of tailings filling mortar, solid waste materials such as fly ash, steel slag, and desulfurization ash were introduced to improve the filling mortar. The Response Surface Methodology (RSM) was used to design the test ratios to determine the significance of the effect of fly ash, steel slag and desulphurization ash on the physical properties of the mortar. The rheological characterization law of filling mortar was studied based on macroscopic L-tube test. The mechanism of filling mortar improvement was analyzed by Scanning Electron Microscopy (SEM), and Energy-Dispersive X-ray Spectroscopy (EDS) and other microscopic tests. The results show that the response-factor model fit regression is significant, with the highest model satisfaction at 12 % fly ash dosing, 15 % steel slag dosing, and 10 % desulfurization ash dosing. The self-flowing extension diameter of the mortar is 15.34 cm, and the 3d and 28d strengths are 0.58 MPa and 3.24 MPa, respectively. Fly ash has effectively improved the phenomenon of mortar segregation and precipitation, and the yield stress of mortar is reduced by 35.1∼64.9 % when the dosage is 8∼12 %. The fractal dimension and mortar workability are positively correlated with fly ash admixture. Fly ash incorporation will gradually consume the calcium hydroxide (CH) to generate alumina ferrite (Aft) and calcium silicate hydrate (C-S-H), which reduces mortar porosity and promotes long-term strength growth. The research results not only realized the effective utilization of solid waste resources, but also significantly improved the performance of the filler and ensured the safe production of the mine.

International Development Trends in the Field of Agricultural Resources and the Environment

The development trends and research layout of agricultural resources and the environment (ARE) are the focus of global attention. In this study, we compiled a data set of SCI papers published in the ARE field since the 13th Five-Year Plan. Thereafter, the topic extraction model of Latent Dirichlet Allocation (LDA) was used to mine the text content so as to explore the research layout of global ARE. The results show that, between 2016 and the time of this study, 31,559 articles were published in the ARE field, exhibiting an overall upward trend. During this time, China and the United States were the main forces in paper publishing. The Chinese Academy of Sciences (CAS), Northwest Agriculture and Forestry University, and the US Department of Agriculture were the top three publishing institutions. Research institutes in China, the United States, Russia, Sweden, the Netherlands, Brazil, and Australia cooperated closely, and the CAS was at the center of the cooperation network. The clustering results of text topics based on the LDA model show that three topics—namely, the interaction mechanisms of plants, the rhizosphere, and microorganisms; the mechanisms and predictive evaluation of soil landslides or erosion; and the decomposition and interaction response of organic matter in agroforestry ecosystems—have been the hot research areas in this field since 2016. The management and efficient utilization of farmland nutrients, and the technology and mechanisms of agricultural waste resource utilization have become key research directions since 2019. The research layouts of China and the United States in this field were analyzed, and the similarities and differences were compared. In addition, suggestions for the future development of ARE are proposed. This study is of great significance for the overall development trend of ARE, the timely tracking of scientific research hotspots, outlining key research and development directions, and promoting scientific and technological innovation.

N, S co-doped porous carbon derived from waste medical masks to support LaFexCo1-xO3 as highly effective peroxymonosulfate catalysts for degradation of tetracycline

N and S co-doped porous carbon was prepared by decorating the waste disposable medical masks (WDMM) with thioacetamide (TAA) as the N/S source and then carbonizing at high temperature, which was subsequently incorporated Co-doped LaFeO3 to obtain NSC@LaFexCo1-xO3 catalysts. The resulting catalysts were used to construct an advanced oxidation process (AOP) based on activation of peroxymonosulfate (PMS) to degrade tetracycline (TC) in water. The physicochemical properties of the as-obtained catalysts were characterized and environmental factors affecting the catalytic performances of NSC@LaFexCo1-xO3/PMS were systematically investigated. The results showed that N and S co-doped porous carbon derived from thioacetamide (TAA)-functionalized WDMM at high temperature could be used as good support for LaFexCo1-xO3. The synergistic effects between N/S co-doped carbon and polyvalent metals (Co2+/Co3+ and Fe3+/Fe2+) endowed NSC@LaFexCo1-xO3 with enhanced catalytic performances, in which nearly 100% of TC could be removed by NSC@LaFe0.95Co0.05O3/PMS system within 10 min under the conditions of 0.2 g/L of catalyst dose, 2.5 mmol/L of PMS concentration and 10 mg/L of initial TC concentration. Furthermore, the constructed NSC@LaFe0.95Co0.05O3/PMS system exhibited a wider pH adaptability (3.0 ∼ 10.0), good salt resistance and reusability as well as high mineralization. The mechanisms and possible pathways of TC degradation by NSC@LaFe0.95Co0.05O3/PMS system were proposed and the ecotoxicity of TC and its intermediates was also evaluated. This study demonstrated the feasible transformation of waste masks into porous carbon with high added value for water pollution control and remediation, accomplishing the dual purposes of recycling and resource utilization of waste masks and protecting the environment.

Effects of rice husk biochar attachment biofilm with microorganisms on nitrogen removal of digested swine wastewater

Nitrogen in digested swine wastewater is currently difficult to directly degrade by an activated sludge process in a sequencing batch reactor (SBR), with resulting failure of the effluent to meet emission standards. In this study, rice husk biochar was optionally added into SBR to enhance biochemical properties for digested swine wastewater, especially for nitrogen degradation. The relative nitrogen removal mechanism for microbial community was probed by means of high-throughput sequencing. The results indicated that chemical oxygen demand (COD), ammonia (NH4+-N), and total nitrogen (TN) removal efficiency of digested swine wastewater was separately at 85.3%, 81.3%, and 65.2% using rice husk biochar with biofilm, which was 3.5%, 24.4%, and 14.7% higher than that of activated sludge, under influent of 2609 mg·L-1 COD, 337.0 mg·L-1 NH4+-N, 344 mg/L TN, and 7.77 C/N. High-throughput sequencing revealed that rice husk biochar with biofilm contained Proteobacteria, Thauera, Comamonas, Acinetobacter, Pseudomonas, Flavobacterium, and Corynebacterium to enhance nitrogen removal of digested swine wastewater. The results not only provide theoretical support for biochar with biofilm to improve digested piggery wastewater treatment, but also have great significance in resource utilization of agricultural waste and eco-environmental protection.

Interfacial interaction mechanism between Mn doped highly conjugated biochar and berberine hydrochloride

MnSO4-modified biochar (Mn-BC) was synthesized to remove berberine hydrochloride (BH) from wastewater by utilizing tea waste as raw material and MnSO4 as modifier. Brunel Emmett Taylor (BET) analysis reveals that the specific surface area (SSA) and average pore size (Dave) of Mn-BC are 1.4 and 7 times higher than those of pristine biochar apart, attributing to the dissociation effect can promote the dispersion of MnSO4 in the pores of the biochar. Meanwhile, the doping of Mn not only introduces additional oxygen-containing functional groups (OCFGs), but also modulates the π electron density. Furthermore, Response surface method (RSM) analysis reveals that Mn-BC dosage has the most significant effect on BH removal, followed by BH concentration and pH value. Kinetic and isothermal studies reveal that the BH adsorption process of Mn-BC was mainly dominated by chemical and monolayer adsorption. Meanwhile, density functional theory (DFT) calculations confirm the contribution of Mn doping to the conjugation effect in the adsorption system. Originally proposed Mn-BC is one potentially propitious material to eliminate BH from wastewater, meanwhile this also provides a newfangled conception over the sustainable utilization of tea waste resources.

Coevolution Mechanism of Remanufacturer–Construction Enterprise–Public in Construction and Demolition Waste Resource Utilization Projects under Green Value Co-Creation

The utilization of resources plays a crucial role in mitigating the environmental pollution issue that improper disposal of construction and demolition waste (CDW) causes. However, the slow growth of the recycled building materials market limits the development of CDW resource utilization. Green value co-creation among remanufacturers, construction enterprises, and the public in CDW resource utilization projects is an effective way to address the issue. This study, based on the theory of value co-creation, uses the evolutionary game method to construct an evolutionary game model for CDW resource utilization projects. The main conclusions are as follows: (1) When the degree of green value co-creation is 0.1 or 0.5, the remanufacturer, the construction enterprise, and the public cannot maintain a state of green value co-creation; when the degree of green value co-creation is 0.9, the remanufacturer, the construction enterprise, and the public in the CDW resource utilization project finally reach a stable state of green value co-creation. (2) When the degree of green value co-creation is 0.5, enhancing the green value co-creation willingness of the remanufacturer or the public can lead other CDW resource utilization project stakeholders to participate in green value co-creation. This study contributes to the promotion of stakeholder cooperation in CDW resource utilization projects, thus providing implications for the promotion of CDW resources.

Interaction mechanism and pollutant emission characteristics of sewage sludge and corncob co-combustion

The co-combustion of sewage sludge and biomass has demonstrated significant potential for reducing carbon emissions and realizing the resource utilization of solid waste. In this study, the co-combustion behavior and pollutant emissions of sewage sludge and corncob were systematically investigated using thermogravimetric-Fourier transform infrared spectroscopy-mass spectrometry (TG-FTIR-MS) and a fixed-bed reactor. When the corncob blending ratio reached 30 %, the ignition temperature was 179.01 °C lower than that of sewage sludge, and the comprehensive combustion index increased by 13.92 times. The corncob in the mixed fuel dominated the volatiles' release and combustion process. The interaction strength increased as the corncob blending ratio increased. When the corncob blending ratio reached 70 %, it promoted the thermal weight loss process of sewage sludge. The release rate of CO2 increased as the biomass ratio increased, and a 30 % corncob content could inhibit CO2 emissions. Simultaneously, the interaction between sewage sludge and corncob inhibited the emissions of CO and NO during the co-combustion process, improving the combustion efficiency. This study provides theoretical support for developing the fuel value of sewage sludge, improving the amount of solid waste collaborative disposal, and realizing the leading carbon peak in thermal power industry.

Cultivation of earthworms and analysis of associated bacterial communities during earthworms’ growth using two types of agricultural wastes

Earthworm cultivation can effectively promote the resource utilization of agricultural waste. The efficient utilization of agricultural waste by earthworms mainly depends on the microbial communities in the guts. This study used silkworm excrement and cow manure as substrates for earthworm cultivation and investigated the associated bacterial communities during earthworms’ growth. The survival rate of earthworms remained above 89% after 21 days of feeding with the two substrates. Proteobacteria, Actinobacteria, and Firmicutes constituted the predominant bacterial communities in earthworm growth, accounting for over 81% of the relative abundance in both guts and vermicompost. The bacteria richness and diversity in the foregut and midgut of earthworm were lower than those in the hindgut. The prediction function of intestinal bacterial communities of earthworms cultured with two substrates mainly involved biosynthesis, decomposition and energy production.

Assessment of the engineering properties of concrete prepared with aggregates developed from waste basalt mud

The development of high-performance aggregate is a key direction of sustainable concrete. One effective synthetic technology for producing artificial aggregates is hydrothermal synthesis. Using waste basalt mud from the construction of a low-carbon industrial park as a raw material further facilitates the utilization of solid waste resources. Therefore, this paper adopted the hydrothermal synthesis method to produce artificial aggregates developed from basalt mud (AABM). Subsequently, it was used to partially replace mechanical aggregate in the preparation of concrete with strength grad C30. The engineering properties of concrete prepared with AABM (C-AABM), including workability, densities, mechanical properties, and frost resistance, were investigated to assess the feasibility of using AABM as concrete aggregates. The results showed that the fluidity of C-AABM can be significantly improved by using AABM. The hardened C-AABM, prepared with 10 ∼ 30 vol% AABM instead of mechanized aggregate, exhibited a dry density decrease of less than 5 %, indicating the feasibility of using AABM for ordinary concrete. However, excessive AABM negatively affected the mechanical properties of the concrete. When the AABM substitution was no more than 15 vol%, the impact of AABM on the compressive strength and modulus of elasticity of C-AABM was less than 15 %. Nevertheless, the performance of the concrete deteriorated dramatically with the addition of AABM under freezing conditions. As described, the primary engineering advantage of preparing C30 concrete with AABM is to improve the workability of the fresh matrix without significantly reducing the mechanical properties of the hardened concrete. It proves the viability of AABM as an alternative aggregate for ordinary concrete production.

Recent progress and perspectives of typical renewable bio-based flocculants: characteristics and application in wastewater treatment.

The research on bio-based flocculants for waste resource utilization and environmental protection has garnered significant attention. Bio-based flocculants encompass plant-based, animal-based, and microbial variants that are prepared and modified through biological, chemical, and physical methods. These flocculants possess abundant functional groups, unique structures, and distinctive characteristics. This review comprehensively discussed the removal rates of conventional pollutants and emerging pollutants by bio-based flocculants, the interaction between these flocculants and pollutants, their impact on flocculation performance in wastewater treatment, as well as their application cost. Furthermore, it described the common challenges faced by bio-based flocculants in practical applications along with various improvement strategies to address them. With their safety profile, environmental friendliness, efficiency, renewability, and wide availability from diverse sources, bio-based flocculants hold great potential for widespread use in wastewater treatment.

Advancing hydrogen generation: Kinetic insights and process refinement for sorption-enhanced steam gasification of biomass utilizing waste carbide slag

Sorption enhanced steam gasification of biomass (SESGB) presents a promising approach for producing high-purity H2 with potential for zero or negative carbon emissions. This study investigated the effects of gasification temperature, CaO to carbon in biomass molar ratio [CaO/C], and steam flow on the SESGB process, employing carbide slag (CS) and its modifications, CSSi2 (mass ratio of CS to SiO2 is 98:2) and CSCG5 (mass ratio of CS to coal gangue (CG) is 95:5), as CaO-based sorbents. The investigation included non-isothermal and isothermal gasification experiments and kinetic analyses using corn cob (CC) in a macro-weight thermogravimetric setup, alongside a fixed-bed pyrolysis-gasification system to assess operational parameter effects on gas product. The results suggested that CO2 capture by CaO reduced the mass loss during the main gasification as the [CaO/C] increased. The appropriate temperature for SESGB process should be selected between 550 and 700 °C at atmospheric pressure. The appropriate amount of sorbent or steam could facilitate the gasification reaction, but excessive addition led to adverse effects. Operational parameters influenced the apparent activation energy (Ea) by affecting various gasification reactions. For each test, Ea at the char gasification stage was significantly higher than that at the rapid pyrolysis stage. The addition of CS notably increased H2 concentration and yield, while sharply reducing CO2 levels. H2 concentration initially rose and then fell with greater steam flow, peaking at 76.11 vol% for a steam flow of 1.0 g/min. H2 yield peaked at 298 mL/g biomass with a steam flow of 1.5 g/min, a gasification temperature of 600 °C and a [CaO/C] of 1.0. Increasing gasification temperature remarkably boosted the H2 and CO2 yields. Optimal conditions for the SESGB using CS as a sorbent, determined via response surface methodology (RSM), include a gasification temperature of 666 °C, a [CaO/C] of 1.99, and a steam flow of 0.5 g/min, under which H2 and CO2 yields were 464 and 48 mL/g biomass, respectively. CSSi2 and CSCG5 demonstrated excellent cyclic H2 production stability, maintaining H2 yields around 440 mL/g biomass and low CO2 yields (∼60 mL/g biomass) across five cycles. The study results offer new insights for the high-value utilization of agroforestry biomass and the reduction and resource utilization of industrial waste.

Comparison on Environmental Benefits of Municipal Solid Waste Management in Suzhou Before and After Classification

In order to systematically understand the urban environmental benefit improvement of municipal solid waste （MSW） classification, based on the disposal data of MSW before and after the MSW classification in Suzhou from 2017 to 2021, the environmental impact potential （EIP） of the MSW collection-transportation-disposal process was calculated, and the environmental benefits of the MSW integrated management in Suzhou to 2035 were predicted. After the MSW classification in Suzhou at the end of 2019, the EIP （in terms of PET2000, the same below） of the per unit weight of MSW was reduced by 18.38% from 2.34×10-13 t-1 in 2017 to 1.91×10-13 t-1 in 2021. The environmental benefits of the MSW integrated management could be improved by classification. Based on the Suzhou MSW removal and transportation situation in 2021, different classification and disposal scenarios were established to calculate. It was found that after the classification effect showed gradient improvement, and the disposal capacity matched accordingly, the environmental benefits of MSW were further improved. Under the planning disposal capacity scenario of "zero waste to landfill", the EIP and the total carbon emissions of per unit weight of MSW should be reduced by 23.96% and 30.73%, respectively, compared with the actual situation in 2021. Based on the linear model of population and economic development level of Suzhou, it is expected that the annual production of MSW in Suzhou will be increased to 6.965 million tons in 2035. Under the background of continuous improvement of MSW classification and continuous optimization of city appearance and environment in Suzhou, based on the status quo of terminal disposal capacity in Suzhou, the EIP of per unit weight of MSW after improving the efficiency of classification by 2035 was predicted to be 1.54×10-13 t-1, the total EIP would be 1.05×10-6, and the total carbon emissions would increase to 3.80 million tons. Under the ideal scenario of expanding the scale of waste disposal, "zero landfill" of raw MSW, and full resource utilization of food waste, the EIP of per unit weight of MSW in 2035 was predicted to be 1.28×10-13 t-1, and the total EIP and the total carbon emissions would be 8.69×10-7 and 3.23 million tons, respectively, which was approximately 5.65% and 1.23% less than the actual scenario in 2021, respectively. The EIP and carbon emissions of MSW integrated management could be controlled better by the coordinated promotion of classified collection and transportation and quality disposal.

Mechanical Properties and Durability of Steel Slag-mineral Powder-coal Gangue Mixture by Uniform Design for Pavement Base

To realize the utilization of industrial solid waste resources and solve the shortage problem of pavement materials, this paper uses steel slag, mineral powder, and coal gangue to prepare a mixture. A uniform test with 2 factors and 6 levels was designed. Through regression analysis, response surfaces were established to study the mechanical properties of the coal gangue mixture. The hydrated products at different ages were microscopically analyzed by XRD and SEM. The durability including freeze-thaw cycles, dry and wet cycles, and immersion expansion rate were researched. The results show that the 7d unconfined compressive strength of the mixture reaches 2.14 – 6.46 MPa, with a 180d resilience modulus of 954 – 1098 MPa, and a 180d splitting tensile strength of 0.66 – 0.83 MPa. With the increase of steel slag content, the 7d unconfined compressive strength of the mixture first decreases and then increases. The content of mineral powder is positively correlated with the 7d unconfined compressive strength. The 180d compressive resilience modulus decreases first and then increases with the increase of steel slag and mineral powder content. The 180d splitting tensile strength is positively correlated with the content of steel slag and mineral powder. The mixture is less affected by freeze-thaw cycles, with mass loss rates of only 1.77 % – 2.13 %. The mass loss rate of the admixture is 0.87 % – 0.99 % after 10 dry and wet cycles, and the strength is slightly improved. The maximum expansion rate of the mixtures immersed in water for 10d is only 0.28 %. The hydrated reaction between steel slag, mineral powder and coal gangue promotes the formation of more hydration products such as AFt, C-S-H, CaAl2(SiO4), and Ca(OH)2. The C-S-H and CaAl2(SiO4) are intertwined into a dense network to wrap Ca(OH)2, which improves the compactness of the mixture and effectively resists the freeze-thaw expansion stress. The steel slag-mineral powder-coal gangue mixture meets the requirements of relevant norms and can be well used in pavement bases.