For the bibliometric analysis, Scopus was selected as the main database due to its broad multidisciplinary coverage, encompassing areas such as physical sciences, health sciences, biological sciences, social sciences, and humanities. ¹⁴ Scopus is particularly suitable for bibliometric studies because of its extensive repository of indexed publications and standardized metadata structure, which facilitates citation analysis, co-authorship mapping, keyword co-occurrence analysis, and other bibliometric indicators essential for comprehensive scientific evaluation. ^{13, 15} In addition, Scopus offers strong compatibility with bibliometric tools such as Bibliometrix and VOSviewer, supporting reproducible quantitative and network-based analyses. Although other scientific databases, including Web of Science and Google Scholar, also contain relevant literature on waste management research, Scopus was selected to ensure consistency in citation indexing and reduce duplication during network analysis. Nevertheless, the exclusive use of Scopus may have limited the inclusion of some regional or non-indexed publications, particularly from developing countries.

To ensure the relevance and quality of the articles included in this bibliometric analysis, specific inclusion and exclusion criteria were established. Original research articles, systematic reviews, book chapters and conference proceedings published between 2000 and 2023, written in English, Spanish or Portuguese, were included. Papers had to explicitly address organic waste management in the context of municipal markets or similar urban areas. Editorials, letters to the editor, brief notes, and articles that did not undergo peer review were excluded. In addition, studies that focused exclusively on industrial or agricultural waste were discarded, as well as those that dealt with waste management in general without a specific focus on organic waste from markets. Results were exported in.CSV format for further analysis, and included key data such as titles, authors, affiliations, keywords, abstracts, number of citations, countries of publication and journals.

A PRISMA-based screening framework was applied to improve transparency and reproducibility in the study selection process. The identification stage included records retrieved from the Scopus database using the predefined search equation. Duplicate records and studies not directly related to organic waste management in municipal marketplaces were removed during the screening stage through title and abstract evaluation. Full-text assessment was subsequently performed to verify eligibility according to the established inclusion and exclusion criteria. The final dataset consisted of 206 publications included for bibliometric analysis. The complete study selection process is presented in Figure 1.

The design of the search algorithm followed the best practices in the construction of equations for bibliometric analysis. ¹⁶ This algorithm was developed to capture relevant literature on organic waste management in urban and municipal settings, including key terms related to organic waste, urban markets, and management strategies. The search included international terms and covered both traditional and innovative technological solutions such as composting, bioconversion and circular economy. The search equation implemented in Scopus was as follows:

For the processing and analysis of bibliometric data, two main tools were used: Bibliometrix and VOSviewer. Bibliometrix, an open-source package for R, was employed to perform quantitative analyses of scientific production, including annual publication trends, author productivity, journal distribution, and country contributions. ¹⁷ In addition, keyword normalization procedures were applied to standardize synonymous terms and translate non-English keywords into English, reducing fragmentation during co-occurrence analysis. Bibliometric networks were constructed using co-occurrence and co-authorship matrices generated within Bibliometrix. ¹³

VOSviewer was used for network visualization and mapping of bibliometric relationships, including co-authorship networks, keyword co-occurrence, and international collaboration patterns. ¹⁸ Association strength normalization and clustering algorithms implemented in VOSviewer were used to identify thematic structures and research clusters. ¹⁶ Network visualizations were generated using distance-based mapping techniques to improve the interpretation of relationships between authors, countries, and research themes. The combined use of Bibliometrix and VOSviewer provided both quantitative and visual insights into trends and patterns in organic waste management research in municipal marketplaces.

Productivity by year: The number of publications per year was analyzed to identify temporal trends in research on organic waste management in municipal markets. This analysis allowed us to observe peaks in research activity and influences of global events or policies.

Productivity by author: The most prolific authors in the field were identified and ranked, evaluating their contribution in terms of number of publications. This metric allows us to measure the influence of key researchers in the development of waste management solutions.

Productivity by journal: The productivity of the main scientific journals that have published on organic waste management was analyzed, highlighting the most influential publications by number of articles and their impact on the scientific community.

Geographical distribution: This analysis evaluated the global distribution of scientific production, allowing the identification of the most active countries in research on organic waste management in municipal markets. The visualization of these data showed the main research centers and their growth over time.

Keywords: Keyword co-occurrence analysis was used to identify the most researched thematic areas and emerging trends in the field. The clusters identified reflect the main lines of research, such as composting, circular economy and environmental impact of waste.

Strategic diagram: The strategic diagram was used to classify research themes according to their degree of development (density) and their relevance within the research field (centrality). Themes with high centrality and high density were considered motor themes, representing well-developed and influential research areas. Themes with high centrality but low density were categorized as basic themes, reflecting important but less developed topics. Conversely, themes with low centrality and high density were identified as niche themes, characterized by specialized but isolated development. Finally, themes with low centrality and low density were considered emerging or declining themes, representing either newly developing topics or areas with decreasing research interest. This analysis provided a conceptual overview of the thematic structure and evolution of research on organic waste management in municipal marketplaces. ^{13, 16}

Cross-country collaboration: International collaboration was evaluated, identifying the most active networks of interaction between countries. This analysis revealed the global research dynamics and how countries have collaborated to solve common problems related to organic waste.

Collaboration between authors: Co-authorship networks were analyzed to identify connections between key researchers. This analysis showed collaboration clusters, highlighting networks of researchers who have led significant advances in the field.

Methodology – Research Trends in Organic Waste Management in Municipal Marketplaces: A Bibliometric Analysis.

Productivity per year

The sustained growth of annual scientific publications reflects an increased interest in organic waste management in municipal markets. Respect to the Figure 2 in fact, in the early years (between 2000 and 2015), the number of publications can be considered low, which could be interpreted as a first period of exploration of the topic in environmental sciences and waste management ¹⁹ ; gradually growing in step with a first focus linked to sustainability and proper management of resources in urban areas, particularly in municipal markets. ²⁰

From 2015 onwards, the number of existing publications is considerably higher, which could be associated with the already consolidated concern for the circular economy and the SDGs as global goals. ¹⁹ In this period, everyone starts to become aware of the need to reuse, recycle and valorize waste as part of an urban sustainability agenda, especially in local and urban markets. ²¹ This boom may also be the result of stricter environmental policies and increased funding for innovative research. ²⁰

The most significant increase in scientific production was observed around 2021, reflecting the growing global interest in circular economy strategies, sustainable waste management, and urban resilience. This increase was also influenced by broader environmental policies and international sustainability agendas that promoted research on waste valorization and resource recovery. Although the COVID-19 pandemic temporarily redirected part of the scientific focus toward healthcare-related waste management, research on organic waste management in municipal marketplaces continued to expand due to its relevance for urban sustainability and circular economy initiatives. ^{19– 21}

Following this period of accelerated scientific growth, a slight decrease in publication output after 2021 was observed, which may reflect changes in research priorities and funding dynamics following the COVID-19 pandemic. Previous studies have suggested that part of the scientific attention during this period shifted toward healthcare and medical waste management topics. ²⁰ Nevertheless, continued scientific production in organic waste management indicates that the field remains highly relevant within global sustainability and circular economy agendas. ¹⁹

Productivity by author

Figure 3a presents the most productive authors in the field of organic waste management in municipal marketplaces and related urban waste systems. The results indicate a relatively dispersed authorship structure, characterized by a limited number of highly productive researchers and a broader group of authors with fewer contributions. Zurbrügg and Tilley emerged as the most influential authors, with four and three publications, respectively, mainly associated with research on sanitation systems, composting, and resource recovery in developing regions. The remaining authors presented two publications each, suggesting that research in this field is still developing through geographically distributed and interdisciplinary contributions rather than through highly consolidated research groups. This pattern reflects the emerging and collaborative nature of research on sustainable organic waste management in municipal market systems.

Zurbrügg and Tilley emerged as the most influential authors in the dataset, contributing significantly to research on composting systems, sanitation technologies, waste valorization, and resource recovery, particularly in developing regions. Their studies have emphasized sustainable and low-cost approaches for organic waste treatment, including composting and black soldier fly-based bioconversion systems, while also highlighting the importance of integrating sanitation and public health perspectives into waste management strategies. ^{22– 26}

Mpanang’ombe has contributed to the understanding of waste management challenges in rapidly urbanizing African regions, emphasizing the need for context-specific policies and improved waste management systems adapted to local socioeconomic conditions. ^{27, 28}

Zhang and Wang have focused on technological valorization approaches, including sustainable composting, refuse-derived fuel production, bioenergy generation, and the use of black soldier fly larvae in organic waste treatment processes. Their contributions reinforce the growing interest in circular economy strategies and resource recovery technologies for urban organic waste management. ^{29– 32}

The temporal evolution of scientific production among these authors reflects the increasing global interest in sustainable organic waste management solutions. The geographic and thematic diversity represented by these contributions highlights the multidisciplinary nature of the field, encompassing environmental engineering, urban sustainability, public health, and circular economy approaches. Collectively, these studies provide an important scientific foundation for future research and policy development aimed at improving waste management systems in municipal marketplaces and other urban environments. ^{5, 33}

Productivity per journal

Figure 3b presents the scientific journals with the highest publication output related to organic waste management in municipal marketplaces. Journal of Cleaner Production emerged as the leading publication source with 10 articles, followed by Sustainability with 9 publications and Waste Management with 7 publications. The predominance of these journals reflects the growing integration of organic waste management research with broader themes such as sustainability, circular economy, environmental management, and resource recovery. ⁸ The strong presence of interdisciplinary journals indicates that organic waste management is increasingly being addressed not only as a technical issue but also as a critical component of sustainable urban development and environmental policy.

The presence of journals such as Bioresource Technology, Resources, Conservation and Recycling, and Journal of Material Cycles and Waste Management highlights the increasing scientific interest in technological valorization processes, including composting, anaerobic digestion, recycling technologies, and bioenergy production. In contrast, journals such as Biocycle provide a more applied perspective focused on practical waste treatment and composting systems. Together, these publication sources demonstrate the interdisciplinary and applied nature of research on organic waste management in municipal marketplaces. ^{34– 36}

Overall, the distribution of publications across both high-impact interdisciplinary journals and specialized waste management journals reflects the growing global relevance of organic waste management within sustainability and circular economy agendas. This diversity of publication outlets also highlights the need for integrated approaches combining technological innovation, environmental policy, and practical waste management strategies to address the challenges associated with municipal organic waste systems.

Geographical distribution

Figure 4 presents the country collaboration map for research on organic waste management in municipal marketplaces and related urban waste systems. The results show a geographically diverse but unevenly distributed research landscape. The United States, India, and China appear as prominent contributors, as indicated by the higher publication intensity observed in these countries. This pattern suggests that research activity is concentrated in countries with strong scientific infrastructure, large urban populations, and increasing pressure to develop sustainable waste management systems. ^{37, 38}

European countries, including the United Kingdom, Spain, Italy, Germany, and the Netherlands, also show relevant participation and act as important nodes in international collaboration. These connections may be associated with the strong policy emphasis on circular economy, resource efficiency, and sustainable waste management within the European context. ⁹ In Asia, India and China stand out not only because of their publication output but also because of their links with other regions, reflecting their growing role in global research on urban sustainability and waste valorization.

In Latin America, Brazil appears as the most visible contributor, while participation from other countries in the region remains limited. Similarly, in Africa, countries such as Ghana, Nigeria, and South Africa are represented but appear less integrated into the global collaboration network. This underrepresentation may reflect limitations related to research funding, institutional capacity, and access to international scientific networks. ¹⁰

Taken together, the collaboration map highlights the global relevance of organic waste management while also revealing persistent geographical disparities. Strengthening North–South and South–South collaboration is essential to promote knowledge transfer, improve regional research capacity, and develop context-specific solutions for municipal organic waste management in underrepresented regions.

Keywords

Figure 5 presents the keyword co-occurrence map which illustrates the conceptual structure of research on organic waste management in municipal marketplaces and related urban waste systems. The network reveals three main thematic clusters indicating that the field is organized around biological treatment technological valorization and sustainability-oriented management approaches.

The red cluster is mainly associated with composting and practical organic waste management. It includes terms such as compost, organic wastes, municipal solid waste, markets, developing countries, and waste composition. This cluster reflects the importance of composting as a widely used and accessible strategy for stabilizing biodegradable residues and recovering nutrients, particularly in contexts where municipal markets generate heterogeneous organic waste streams. ^{29– 31}

The green cluster is centered on anaerobic digestion and includes related terms such as biogas, methane, digestate, bioenergy, waste-to-energy, life cycle assessment, biochar, and biorefinery. This thematic group highlights the growing interest in technological valorization and energy recovery from organic waste. The presence of life cycle assessment within this cluster also suggests increasing attention to the environmental evaluation of waste treatment alternatives. ^{23, 32, 35, 39}

The blue cluster is structured around food wastes, organic waste management, and circular economy, together with terms such as sustainability, resource recovery, and economic feasibility. This cluster represents a broader systems-oriented perspective, linking organic waste management with circular economy principles, sustainability assessment, and the economic viability of waste valorization strategies. ^{19, 34}

These thematic connections suggest that research in this field has evolved from conventional waste treatment approaches toward more integrated frameworks that combine composting, anaerobic digestion, resource recovery, and circular economy strategies. The central position of terms such as food wastes, organic waste management, compost, and anaerobic digestion indicates that these concepts act as bridges between practical waste management, technological innovation, and sustainability-oriented research.

Strategic diagram

Figure 6 presents the strategic diagram of research themes related to organic waste management in municipal marketplaces and related urban waste systems. The diagram classifies themes according to their relevance degree (centrality) and development degree (density), allowing the identification of motor, basic, niche, and emerging or declining themes.

The motor themes quadrant includes anaerobic digestion, bio gas, and market waste. These themes show both high centrality and high density, indicating that they are well-developed and strongly connected to the overall research field. Their position reflects the growing importance of energy recovery and biological conversion processes in organic waste valorization, particularly in the context of municipal market waste streams. ^{23, 32, 35}

The basic themes quadrant includes compost, organic wastes, and organic waste management. These themes show high relevance but lower development, suggesting that they represent foundational topics within the field. Composting remains a central and widely applied strategy for stabilizing biodegradable residues and recovering nutrients, especially in contexts where low-cost and locally adaptable solutions are required. ^{29– 31}

The niche themes quadrant includes life cycle assessment, biochar, and landfill. These themes are relatively well developed internally but less connected to the broader conceptual structure of the field. This suggests that environmental assessment tools and alternative treatment pathways are gaining specialized attention, although they remain more peripheral compared with composting and anaerobic digestion.

Themes such as bioenergy, waste to energy, and municipal solid wastes appear close to the lower central area of the diagram, indicating transitional or emerging relevance. Their position suggests that energy recovery from organic waste is becoming increasingly important but may still require stronger integration with broader sustainability and circular economy frameworks. Similarly, food wastes, circular bioeconomy, and sustainability appear near the center of the diagram, reflecting their role as cross-cutting concepts that connect biological treatment, technological valorization, and systems-oriented approaches. ^{19, 34}

The strategic diagram suggests that research in this field is structured around a dual focus: practical organic waste management strategies, represented by composting and organic waste management, and more technologically oriented valorization pathways, represented by anaerobic digestion, biogas, and waste-to-energy approaches. This thematic structure confirms the transition from conventional waste treatment toward integrated circular economy and resource recovery frameworks. ^{19, 34}

Collaboration between countries

Figure 7a presents the international co-authorship network among countries contributing to research on organic waste management in municipal marketplaces and related urban waste systems. The network shows a centralized structure in which the United States, India, and the United Kingdom occupy prominent positions, both in terms of node size and number of collaborative links. This indicates that these countries play an important role in connecting different research groups and facilitating international knowledge exchange in the field.

India appears as one of the most relevant contributors, with strong collaborative connections involving countries such as the United States, China, Spain, Switzerland, and Denmark. This pattern reflects the growing participation of rapidly urbanizing countries in research on sustainable waste management, resource recovery, and circular economy strategies. ³⁸ China and Italy also appear as relevant nodes, although their collaboration patterns are more closely connected to specific regional or thematic clusters.

The network also shows participation from African countries, including Ghana, Nigeria, Malawi, and Uganda. Their presence is particularly relevant because organic waste management remains a critical issue in many rapidly growing urban areas in developing regions. ^{10, 40} However, these countries appear as smaller and more peripheral nodes, suggesting that their integration into global collaboration networks remains limited.

A separate collaboration group involving the Netherlands, Mexico, Colombia, and Indonesia can also be observed, indicating the existence of more specialized or regionally focused research connections. This distribution suggests that, although international collaboration is present, the field remains fragmented, with most connections concentrated around a limited number of central countries.

These findings suggest the need to strengthen North–South and South–South scientific collaboration to promote knowledge transfer, improve research capacity, and support locally adapted solutions for sustainable organic waste management in municipal marketplaces. ^{10, 33}

Collaboration between authors

Complementing the country-level analysis, Figure 7b presents the co-authorship network among authors contributing to research on organic waste management in municipal marketplaces and related urban waste systems. The network reveals a fragmented collaborative structure composed of several relatively small and disconnected clusters, suggesting that research in this field is still organized around localized or topic-specific collaborations rather than a single, highly integrated international research community.

One of the most cohesive clusters includes authors such as Gavilanes-Terán, Paredes, López, Bustamante, Jara-Samaniego, and Morat, whose collaboration pattern is strongly associated with composting strategies and practical organic waste management in Latin American contexts. ⁴¹ Another relevant cluster includes Liu, Zhang, Awasthi, Chen, and Pandey, reflecting a collaborative focus on technological valorization processes such as composting optimization, biochar, and other resource recovery approaches. ^{29– 31}

A smaller but clearly connected cluster is formed by Zurbrügg, Tilley, and Rajabu, whose work has been particularly influential in sanitation, low-cost biowaste treatment, and sustainable resource recovery in developing regions. ^{23, 25, 28} Additional smaller groups, such as those involving Debnath and Ghosh, or De Oliveira and De Medeiros, indicate the presence of specialized research partnerships with more limited integration into the broader collaboration network.

The structure of the network suggests that, although the field has developed multiple active lines of research, co-authorship remains dispersed across thematic and regional groups. This pattern may reflect differences in research priorities, institutional partnerships, methodological approaches, and regional contexts. ³³ In this context, strengthening collaboration across clusters could facilitate greater knowledge exchange, improve methodological integration, and support the development of more comprehensive and globally relevant solutions for organic waste management in municipal marketplaces.