An MFA-LCA framework for goal-oriented waste management studies: 'Zero Waste to Landfill' strategies for institutions.

Institutions such as university communities can be considered miniature versions of the larger society in which they exist. Nonetheless even though it should be easier to manage waste at an institution, their waste management (WM) programmes are typically lack an overall goal for improving environmental impact and are not optimally structured or operated. In part this is due to a lack of a framework that promotes a goal-oriented WM strategy. For instance, zero waste (ZW) to landfill studies have gained prominence in recent years, but generally there is a lack of clear guidance on how to carry out ZW strategies effectively at either, municipal or institutional levels. To fill this gap, this study aims to provide a framework that enables institutions to develop a goal-oriented WM strategy applying the principles of material flow analysis and life cycle assessment. The framework assumes that no prior data are available, and a study will therefore begin by collecting primary data followed by secondary data. The case study is presented in this article, along with the introduction of the framework, using ZW management scenarios in the Istanbul Technical University Ayazaga Campus. The results of the case study show that, it is not possible to achieve ZW to landfill on university campuses. And simply diverting waste from landfill (min 74% to max ~100%) does not necessarily lead to circularity (min 20% to max ~66%) or directly address public attitudes towards ZW goals.

New Perspectives on the Old Uses of Traditional Medicinal and Edible Herbs: Extract and Spent Material of Persicaria hydropiper (L.) Delarbre.

Background/Objectives:Persicaria hydropiper (L.) Delarbre, commonly known as water pepper, possesses multifunctional potential. Our research focuses on its complex phenolic composition, bioactivity, safety evaluation and utilization in a sustainable manner. Moreover, a survey was conducted among the Serbian population to gain insight into the attitude towards traditional wild-growing herbs (i.e., P. hydropiper), the level of familiarity with their zero-waste culture, and to assess eating behaviors. Methods: A survey was conducted with 168 participants to assess attitudes towards traditional herbs, zero-waste culture, and eating behaviors, while cytotoxicity, in vivo toxicity, chemical analysis of secondary metabolites, and probiotic viability assays were performed to evaluate the effects of the PH extract. Results: Notably, P. hydropiper extract (PH) exhibits a diverse phenolic profile, including quinic acid (3.68 ± 0.37 mg/g DW), gallic acid (1.16 ± 0.10 mg/g DW), quercetin (2.34 ± 0.70 mg/g DW) and kaempferol-3-O-glucoside (4.18 ± 0.17 mg/g DW). These bioactive compounds have been linked to anticancer effects. The tested extract demonstrated a cytotoxic effect on the human neuroblastoma cell line, opening questions for the further exploration of its mechanisms for potential therapeutic applications. Based on the toxicity assessment in the Artemia salina model, the PH could be characterized with good safety, especially for the lower concentrations (LC50 = 0.83 mg/mL, 24 h). The utilization of the spent PH material supports the viability of psychobiotic strains (up to 9.26 ± 0.54 log CFU/mL). Based on the conducted survey, 63.7% (n = 107) of respondents mainly prefer traditional instead of imported herbs. The respondents were skeptical about zero-waste edibles; 51.2% (n = 86) would not try them, and a bit more than half were not familiar with zero-waste culture (57.7%; n = 97). Only 8.3% (n = 14) followed a flexitarian diet as a dietary pattern. Conclusions: The use of underutilized traditional plants and their spent material could potentially contribute to the acceptance of a zero-waste culture in Serbia. Reinventing the use of neglected traditional plants and addressing ways for spent material valorization could contribute to the acceptance of a zero-waste strategy and encourage healthier eating behavior.

Carbon dioxide as a sustainable reagent in circular hydrometallurgy.

This review highlights the use of CO2 as a reagent in hydrometallurgy, with emphasis on the new concept of circular hydrometallurgy. It is shown how waste CO2 can be utilised in hydrometallurgical operations for pH control or regeneration of acids for leaching. Metal-rich raffinate solutions generated after removal of the valuable metals can serve as feedstocks for mineral carbonation, providing alternative avenues for CO2 sequestration. Furthermore, CO2 can also be used as a renewable feedstock for the production of chemical reagents that can find applications in hydrometallurgy as lixiviant, as precipitation reagent or for pH control. Mineral carbonation can be combined with chemical reactions involving metal complexation reagents, as well as with solvent extraction processes for the concurrent precipitation of metal carbonates and acid regeneration. An outlook for future research in the area is also presented.

Utilisation of agricultural residues for antioxidant exopolysaccharide production by Bacillus spp.

This study tested the antioxidant activities of exopolysaccharides (EPSs) produced by eight Bacillus spp. from Thai milk kefir utilising four agricultural by-products in Thailand; copra meal, mangosteen peel, sorghum, and para rubber sawdust as carbon sources. Sorghum showed the highest starch and sugar content of 73.33% while copra meal showed the lowest (13.08%). B. tequilensis PS21 produced the highest dry weight EPS, followed by B. amyloliquefaciens KW1 and B. tequilensis PS22 from four substrates. B. tequilensis PS21 generated the most EPS with sorghum (0.75 ± 0.09 g DW/100 mL culture), followed by mangosteen peel (0.61 ± 0.07 g). EPS from B. amyloliquefaciens KW1 using copra meal displayed the highest DPPH radical scavenging activity of 33.39 ± 1.34% and EPS from the same bacteria using sorghum displayed the highest hydroxyl radical scavenging activity of 49.78 ± 0.86%. This approach demonstrated a bio-circular green economy paradigm in converting agricultural biowastes into valuable EPS biomaterials with potential applications.

Two-step polyhydroxybutyrate production from hydrogenic effluent by freshwater microalgae Coelastrella sp. KKU-P1 and Acutodesmus sp. KKU-P2 under mixotrophic cultivation.

This study aimed to produce PHB using hydrogenic effluent discharged from the biohydrogen production process with freshwater microalgae including Coelastrella sp. KKU-P1, and Acutodesmus sp. KKU-P2. Batch experiments explored the influence of initial pH and hydrogenic effluent concentration, revealing optimal conditions at 10 % (v/v) effluent concentration and a pH of 6.5 for both KKU-P1 and KKU-P2. Subsequently, medium formulation and photoperiods were optimized to maximize biomass and PHB accumulation. The results showed that the optimal condition for PHB accumulation with KKU-P1 and KKU-P2 was nitrogen phosphorus (NP)-limited Bold's Basal Medium (BBM) under dark conditions. A two-step PHB accumulation in the upscale bioreactor was investigated under optimal conditions. The results showed that KKU-P1 achieved maximum PHB, protein, carbohydrate, and lipid contents of 4.57 %, 29.37 %, 24.76 %, and 13.21 %, respectively, whereas KKU-P2 achieved 6.35 %, 31.53 %, 16.16 %, and 4.77 %, respectively. Based on these findings, it appears that a mixotrophic approach under nutrient-limiting conditions is effective for PHB production in both KKU-P1 and KKU-P2 strains.

Enzymes from Fishery and Aquaculture Waste: Research Trends in the Era of Artificial Intelligence and Circular Bio-Economy.

In the era of the blue bio-economy, which promotes the sustainable utilization and exploitation of marine resources for economic growth and development, the fisheries and aquaculture industries still face huge sustainability issues. One of the major challenges of these industries is associated with the generation and management of wastes, which pose a serious threat to human health and the environment if not properly treated. In the best-case scenario, fishery and aquaculture waste is processed into low-value commodities such as fishmeal and fish oil. However, this renewable organic biomass contains a number of highly valuable bioproducts, including enzymes, bioactive peptides, as well as functional proteins and polysaccharides. Marine-derived enzymes are known to have unique physical, chemical and catalytic characteristics and are reported to be superior to those from plant and animal origins. Moreover, it has been established that enzymes from marine species possess cold-adapted properties, which makes them interesting from technological, economic and sustainability points of view. Therefore, this review centers around enzymes from fishery and aquaculture waste, with a special focus on proteases, lipases, carbohydrases, chitinases and transglutaminases. Additionally, the use of fishery and aquaculture waste as a substrate for the production of industrially relevant microbial enzymes is discussed. The application of emerging technologies (i.e., artificial intelligence and machine learning) in microbial enzyme production is also presented.

Zero-waste multistage utilization of dandelion root.

Introduction: In the fragrance and perfume industry, the controlled release of fragrances are crucial factors that contribute to consumer appeal and product quality enhancement. In this study, various aromatic active substances were extracted from dandelion root (DR), which was subsequently calcined to produce high-performance porous biochar material. Methods: The dandelion root biochar (DRB) material was identified as promising adsorbents for the controlled release of fragrances. Furfuryl alcohol was chosen as the model fragrance for inclusion and controlled release studies. Results and discussion: The DRB exhibited a substantial specific surface area of 991.89 m2/g, facilitating efficient storage and controlled release capabilities. Additionally, the DRB's high stability and porous nature facilitated rapid collection and efficient recyclability. This research significantly contributes to the development of a sustainable, zero-waste multistage utilization strategy for dandelion roots, indicating a potential applications in the food flavoring industry and environmental conservations.

Application of the upcycling trend using ultrafiltrate of water from the production of collagen from fish skin in hair care cosmetics.

The aim of the research problem of the article was to try to popularize the upcycling trend in the production of sustainable cosmetics and to confirm their effectiveness. The development of recycled raw materials is a new discovery in the chemical industry. Manufacturers emphasize the production of more environmentally friendly raw materials. Conscious consumers choose cosmetics whose production is based on sustainable development. Instead of throwing away waste from various industries, let us use it to produce active substances used in hair cosmetics. The production of the collagen series was created in accordance with the principles of upcycling, which involves obtaining collagen water, which is waste generated during the production of supplements. The main goal of the work was to learn cosmetic recipes for styling, washing and conditioning hair based on collagen waste, as well as to compare the results of people using the product in question. The aim of the study was also to demonstrate the effectiveness of the treatment in preventing split ends and hair breakage, usually caused by mechanical stress (brushing), as well as to confirm the effectiveness of other tests. The article presents procedures and parameters confirming the effectiveness of treatment with the tested hair products. The following tests were carried out: hair thickness and density, colour uniformity, shine factor and scalp hydration. All parameters numerically confirmed the beneficial effects of products containing collagen water used in hair care.

L'objectif Synthèse: de l'article était de vulgariser la tendance de l'upcycling dans la production de cosmétiques durables et de confirmer leur efficacité. Le développement de matières premières recyclées est une nouvelle découverte dans l'industrie chimique. Les fabricants mettent l'accent sur la production de matières premières plus respectueuses de l'environnement. Les consommateurs responsables vont choisir des cosmétiques dont la production s'appuie sur des principes de développement durable. Les déchets provenant de diverses industries peuvent servir à la fabrication de substances actives utilisées dans les produits de soins des cheveux. La fabrication de produits à base de collagène reposait sur le principe de l'upcycling, qui consistait à obtenir de l'eau de collagène issue des déchets générés lors de la production de compléments alimentaires. Le but principal était d'apprendre des recettes de cosmétiques pour le coiffage, le lavage et le soin des cheveux à partir de déchets de collagène, et de comparer les résultats avec des personnes utilisant le produit en question. L'objectif de l'étude était de démontrer l'efficacité des soins dans la prévention des fourches et de la casse, généralement causés par un stress mécanique tel que le brossage, et de confirmer l'efficacité d'autres tests. L'article présente les procédures et paramètres confirmant l'efficacité du traitement avec les soins capillaires testés. Les tests suivant ont été menés : épaisseur et densité des cheveux, uniformité de la couleur, brillance et hydratation du cuir chevelu. Les chiffres ont parlé et tous les paramètres ont confirmé les effets bénéfiques des produits contenant de l'eau de collagène dans les soins capillaires.

[Spatial Correlation Structure and Influencing Mechanism of Development Level of Zero-waste Cities in China].

Based on the entropy weight TOPSIS method to measure the development level of "zero-waste cities" in China from 2004 to 2021, the social network analysis method and spatial Durbin model were used to explore the spatial correlation network structure and impact mechanism of the development level of "zero-waste cities." The results showed that： ① The development level of "zero-waste cities" was generally on the decline in the whole country and the eastern and central regions. However, it was on the rise in the western regions. ② The spatial correlation of the development level of "zero-waste cities" presented a core-edge structure, with an overall upward trend in network density and a stable state in the overall network. ③ Beijing, Shanghai, Jiangsu, Zhejiang, Fujian, and Guangdong were at the center and dominant position of the network. ④ Beijing, Tianjin, Shanghai, and Jiangsu belonged to the "net benefit" sector； Zhejiang, Fujian, and Guangdong belonged to the "broker" sector； and the other provinces belonged to the "net overflow" sectors. ⑤ The level of urbanization, economic development, technological innovation, foreign investment, environmental regulations, government intervention, and population size had a significant impact on the development level of "zero-waste cities" in local or neighboring provinces, respectively. The research results can provide a reference for the proposal of policies for constructing and coordinating the development of "zero-waste cities" in various regions.

Biosorption of Remazol Brilliant Blue R textile dye using Clostridium beijerinckii by biorefinery approach.

The current study proposes RBBR biosorption by Clostridium beijerinckii DSMZ 6422 biomass remaining after biobutanol production from pumpkin peel (PP) by a zero-waste approach. Efficient biobutanol production was achieved by investigating initial PP concentrations (5-20% without or with enzymatic hydrolysis) and fermentation time. According to this, the highest concentrations of biobutanol and total ABE were obtained as 4.87 g/L and 8.13 g/L in the presence of 10% PP without enzymatic hydrolysis at 96 h. Furthermore, based on the zero-waste approach, C. beijerinckii DSMZ 6422 biomass obtained after biofuel production was used as a biosorbent for the removal of RBBR dye. Response surface methodology (RSM), commonly utilized for the experimental design, was used to specify the optimized biosorption conditions of RBBR, including initial dye concentration (50-200 mg/L), initial pH (2-6), biosorbent concentration (1-3 g/L), and contact time (0-240 min). The highest biosorption under optimized conditions with RSM was 98% in the presence of 194.36 mg/L RBBR and 2.65 g/L biosorbent at pH 2 and 15 min. This is the first report in the literature about the biosorption of RBBR dye by anaerobic C. beijerinckii biomass after the biobutanol production process. This study also shows the efficient usage of agricultural and microbial wastes in different areas based on zero-waste applications.

Exploring the Efficiency of Magnetic Separation and Gravity Concentration for Valorizing Pb-Zn Smelter Slag in a Circular Economy Framework.

The presented work offers an innovative process scheme for valorizing Pb-Zn slag, which involves crushing, grinding, and separation techniques to concentrate valuable components (non-ferrous metals). This methodology could have a significant impact on the global beneficiation of metallurgical slags since it is significantly more simple, environmentally friendly, and cost-effective than standard pyro- and hydrometallurgical procedures. According to previous physicochemical and mineralogical studies, Pb-Zn slag is a valuable secondary raw material. This inhomogeneous technogenic resource contains substantial amounts of non-ferrous metals (Pb, Zn, Cu, and Ag). However, laboratory tests have indicated that the Pb-Zn slag contains highly uneven amounts of valuable metals, ranging from several g/ton to tens of g/ton. The main issue is that traditional metallurgical procedures for releasing beneficial elements are not commercially viable since the elements are "trapped" within the amorphous aluminosilicates or intergrowths of alloy grains and glassy phases. Gravity concentration (Wilfley 13 shaking table) and magnetic separation (Davis separator and disk separator) were used to obtain the final concentrate following comminution and grindability testing. The gravity concentration proved more effective. Namely, magnetic separators could not process nor adequately separate beneficial non-ferrous elements because they were merged together with iron-bearing minerals and aluminosilicates in amorphous Pb-Zn slag grains. With the gravity concentration approach, 12.99% of the processed slag belonged to ∆T fraction (concentration of non-ferrous metal alloys), while remaining 87% corresponded to the tailings fraction (∆L). The total amounts of recovered Pb, Zn, Cu, and Ag from ∆T and ∆L fractions were 5.28%, 6.69%, 0.58%, and 76.12 ppm and 1.22%, 6.05%, 0.43%, and 15.26 ppm, respectively. This streamlined approach to valorizing Pb-Zn slag can reduce the need for hazardous chemicals used in hydrometallurgical refinement operations, as well as the extremely high temperatures required for pyrometallurgical processing. This is the first study to investigate the viability of this novel methodology, which involves the direct examinations of the Pb-Zn slag feed with various alternative technologies for separation and concentration. After extracting the valuable metals, the amorphous aluminosilicate part of the Pb-Zn slag can be reapplied as an alternative raw material in the building sector, adding to the circularity of the suggested approach.

Mangosteen Pericarp Processing Technology to Create Economic Value and Reduce Biowaste.

This research comparatively investigates different mangosteen pericarp processing schemes. The experimental pericarp processing schemes were hot air drying (HAD; control), quick freezing/HAD (QF + HAD), slow freezing/HAD (SF + HAD), and slow freezing/freeze-drying (SF + FD). For freezing, the QF temperature was -38 °C for 2 h and that of SF was -25 °C for 2 weeks. For drying, the HAD temperature was 60 °C for 7 h. In the FD process, the primary and secondary temperatures were -20 °C and 50 °C for 48 h. The experimental results showed that the freezing method (i.e., QF and SF) affected the physical properties (moisture content, water activity, and color) of dried mangosteen pericarp. The antioxidant activities (DPPH and ABTS) of the SF + HAD scheme (28.20 and 26.86 mg Trolox/g DW of mangosteen pericarp) were lower than the SF + FD scheme (40.68 and 41.20 mg Trolox/g DW of mangosteen pericarp). The α-mangostin contents were 82.3 and 78.9 mg/g DW of mangosteen pericarp for FD and HAD, respectively; and the corresponding TPC were 1065.57 and 783.24 mg GAE/g DW of mangosteen pericarp. The results of this study suggest that the drying process had a negligible effect on bioactive compounds. Essentially, the SF + HAD technology is the most operationally and economically viable scheme to process mangosteen pericarp.

Recent advances in recirculating aquaculture systems and role of microalgae to close system loop.

In recirculating aquaculture systems (RAS), waste management of nutrient-rich byproducts accounts for 30-50% of the whole production costs. Integrating microalgae into RAS offers complementary solutions for transforming waste streams into valuable co-products. This review aims to provide an overview of recent advances in microalgae application to enhance RAS performance and derive value from all waste streams by using RAS effluents as microalgal nutrient sources. Aquaculture solid waste can be converted by hydrothermal liquefaction (HTL), then the resultant aqueous phase of HTL can be used for microalgae cultivation. In addition, microalgae generate the required oxygen while sequestering carbon dioxide. The review suggests a novel integrated system focusing on oxygenation and carbon dioxide capture along with recent technological developments concerning efficient microalgae cultivation and nutrient recovery techniques. In such system, microalgae-based biorefineries provide environmentally-conscious and economically-viable pathways for enhanced RAS performance and conversion of effluents into high-value products.

Integral multi-valorization of agro-industrial wastes: A review.

Agriculture and industries related to the agriculture sector generate a large amount of waste each year. These wastes are usually burned or dumped, causing damage to the environment, the economy and society. Due to their composition, they have great potential for obtaining high value-added products in biorefineries. This fact, added to the growing demand for energy and chemicals from fossil resources, is driving the interest of the scientific community in them. Biorefinery processes are hardly profitable when applied individually, so a better alternative is to develop integrated multi-feedstock and multi-product biorefinery schemes using all biomass fractions in a zero-waste approach. However, for industrial scale application, extensive research, scale-up studies, and techno-economic and environmental feasibility analyses are needed. This review compiles information on integrated multi-biorefinery processes from agro-industrial wastes to shed light on the path towards sustainable development and circular bioeconomy.

Upcycling fruit waste into microalgae biotechnology: Perspective views and way forward.

Fruit and vegetable wastes are linked to the depletion of natural resources and can pose serious health and environmental risks (e.g. eutrophication, water and soil pollution, and GHG emissions) if improperly managed. Current waste management practices often fail to recover high-value compounds from fruit wastes. Among emerging valorization methods, the utilization of fruit wastes as a feedstock for microalgal biorefineries is a promising approach for achieving net zero waste and sustainable development goals. This is due to the ability of microalgae to efficiently sequester carbon dioxide through photosynthesis, utilize nutrients in wastewater, grow in facilities located on non-arable land, and produce several commercially valuable compounds with applications in food, biofuels, bioplastics, cosmetics, nutraceuticals, pharmaceutics, and various other industries. However, the application of microalgal biotechnology towards upcycling fruit wastes has yet to be implemented on the industrial scale due to several economic, technical, operational, and regulatory challenges. Here, we identify sources of fruit waste along the food supply chain, evaluate current and emerging fruit waste management practices, describe value-added compounds in fruit wastes, and review current methods of microalgal cultivation using fruit wastes as a fermentation medium. We also propose some novel strategies for the practical implementation of industrial microalgal biorefineries for upcycling fruit waste in the future.

Feasibility of Enzymatic Protein Extraction from a Dehydrated Fish Biomass Obtained from Unsorted Canned Yellowfin Tuna Side Streams: Part II.

The enzymatic extraction of proteins from fish biomasses is being widely investigated. However, little or almost no research has paid attention to the exploitation of unsorted fishery biomasses. This work is part of a larger study, Part I of which has already been published, and focuses on an extensive characterization of two collagenous samples, namely gelatin (G) and hydrolyzed gelatin peptides (HGPs), extracted from a dehydrated fish biomass coming from unsorted canned yellowfin tuna side streams. The results indicate crude protein fractions of 90-93%, pH values between 3 and 5, white-yellow colors, collagen-like FTIR spectra, and 17% in terms of total amino acid content. Viscosity and the study of dynamic viscous-elastic behavior were analyzed. Thermo-gravimetric analysis was performed to assess the residual ashes. Both samples were investigated to determine their molecular weight distribution via size-exclusion chromatography, with a higher total average molecular weight for G compared to HGPs, with values of 17,265.5 Da and 2637.5 Da, respectively. G demonstrated technological properties similar to analogous marine gelatins. HGPs demonstrated antioxidant activity as per FRAP assay. All the results open up new perspectives for the potential use of these substances in biodegradable packaging, dietary supplements, and skin care cosmetics.

A simple tandem bioassay-guided SCX-RP SPE fractionation for efficient active peptide screening from Inca nut cake protein hydrolysate.

Typically, bioactive peptides were uncovered from complex hydrolysates using sequential bioassay-guided fractionation. To increase the efficiency of bioactive peptide screening, a simple and convenient tandem bioassay-guided fractionation based on solid-phase extraction (SPE) was conducted to screen the angiotensin-I-converting enzyme (ACE) inhibitory peptides from the hydrolysate of Inca nut cake protein (INCP). The so-called SCX-RP SPE system was constructed by assembling SCX (strong cation exchange) and RP (reversed phase) SPE cartridges. Using this tandem SCX-RP SPE, the INCP digested with combined gastrointestinal protease (INCP GP) was fractionated into 30 fractions. The fraction F11 exhibited the highest ACE inhibitory activity among 30 fractions. The ACE IC50 of fraction F11 was calculated to be 6.6 ± 0.5 µg/mL. The ACEI activity of fraction F11 was stronger than the INCP GP hydrolysate (ACE IC50 of 12.7 ± 0.4 µg/mL). The tandem SCX-RP SPE fractionation reduced the number of ACE inhibitory (ACEI) peptide candidates from 127 peptides in the INCP GP hydrolysate to only ten peptides in fraction F11. Subsequently, WALPTQSW (WW-8) and WLPTKSW (WW-7) from fraction F11 were synthesized, and their ACE IC50 was determined to be 4.7 ± 0.1 and 7.9 ± 0.1 µM, respectively. The dipeptidyl peptidase-4 (DPP4) inhibitory and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities of WALPTQSW (WW-8) were also explored to give IC50 values of 131.7 ± 5.2 and 191.8 ± 7.0 µM, respectively. The molecular docking and inhibition mechanism studies indicated that WW-8 inhibited ACE and DPP4 as competitive and non-competitive inhibitors, respectively. The pre-incubation experiment of WW-8 toward ACE and DPP4 demonstrated that WW-8 was a true-inhibitor type. Additionally, the amount of WW-8 was quantified to be 5.8 ± 0.2 and 35 ± 0.4 µg per milligram hydrolysate and fraction F11, respectively. This study demonstrated tandem bioassay-guided SCX-RP SPE fractionation efficiently screened ACEI peptide derived from INCP GP hydrolysate, adding more value to Inca nut cake (a leftover of the oil industry) as a bioactive peptide precursor.

How does the digital economy affect the provincial "zero-waste city" construction? Evidence from China.

The digital economy is playing a crucial effect in the field of environmental governance. Digital and intelligent management is an essential means to fully realize the "zero-waste city" construction. The present paper investigates the impact of digital economy on China's provincial "zero-waste city" construction. The results indicate that digital economy can contribute to "zero-waste city" construction. The digital economy has a positive nonlinear effect on the construction of "zero-waste city," but the marginal effect is diminishing. The digital economy can facilitate "zero-waste city" construction by improving industrial structure upgrading and green technology innovation. Heterogeneity analysis reveals that digital economy contributes to the construction of "zero-waste city" in the eastern and western regions and high-level environmental regulation regions, while this impact is insignificant in the central region and low-level environmental regulation regions. The digital economy exerts the most significant positive influence on waste resource recycling followed by waste final disposal and then waste reduction at the source. These findings underscore the effect of digital economy in fostering "zero-waste city" construction and promoting sustainable waste management. The present study provides new ideas for the "zero-waste city" construction in emerging developing countries such as China.

Does the purchase intention of green consumers align with their zero-waste buying behaviour? An empirical study on a proactive approach towards embracing waste-free consumption.

In recent years, emerging retail markets in cosmetics have transformed into green markets, as consumers demand more eco-friendly products. However, in scholarly literature, limited studies are available where researchers discuss green consumers' purchase intentions towards eco-friendly products and their relationship with zero-waste buying behaviour. This study is conducted to address the existing gap in current literature. An empirical investigation is carried out, focusing on individuals who use cosmetic products and are active followers of zero-waste beauty influencers on social media. Responses are gathered for data analysis with the help of partial least squares structural equation modelling (PLS-SEM). The results indicate that eco-friendly packaging, pro-environmental belief, and para-social interaction positively impact the altruistic motivation and purchase intention of consumers. Ultimately, these factors collectively contribute to the purchase of zero-waste cosmetic products. The findings of this study can provide valuable insights for policymakers and brand managers in the field of herbal cosmetic formulations. These insights can help in understanding the fundamental reasons that drive consumers to buy zero-waste cosmetic items, potentially leading to a decrease in ecological impact. Additionally, the study contributes to the theory of planned behaviour (TPB) by investigating consumers' purchase intention towards eco-friendly products and their zero-waste buying behaviour.

Technological solutions to landfill management: Towards recovery of biomethane and carbon neutrality.

Inadequate landfill management poses risks to the environment and human health, necessitating action. Poorly designed and operated landfills release harmful gases, contaminate water, and deplete resources. Aligning landfill management with the Sustainable Development Goals (SDGs) reveals its crucial role in achieving various targets. Urgent transformation of landfill practices is necessary to address challenges like climate change, carbon neutrality, food security, and resource recovery. The scientific community recognizes landfill management's impact on climate change, evidenced by in over 191 published articles (1998-2023). This article presents emerging solutions for sustainable landfill management, including physico-chemical, oxidation, and biological treatments. Each technology is evaluated for practical applications. The article emphasizes landfill management's global significance in pursuing carbon neutrality, prioritizing resource recovery over end-of-pipe treatments. It is important to note that minimizing water, chemical, and energy inputs in nutrient recovery is crucial for achieving carbon neutrality by 2050. Water reuse, energy recovery, and material selection during manufacturing are vital. The potential of water technologies for recovering macro-nutrients from landfill leachate is explored, considering feasibility factors. Integrated waste management approaches, such as recycling and composting, reduce waste and minimize environmental impact. It is conclusively evident that the water technologies not only facilitate the purification of leachate but also enable the recovery of valuable substances such as ammonium, heavy metals, nutrients, and salts. This recovery process holds economic benefits, while the conversion of CH4 and hydrogen into bioenergy and power generation through microbial fuel cells further enhances its potential. Future research should focus on sustainable and cost-effective treatment technologies for landfill leachate. Improving landfill management can mitigate the adverse environmental and health effects of inadequate waste disposal.