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Review

Recent Advances in Sewer Biofilms: A Perspective on Bibliometric Analysis

by
Linjun Zhang
1,2,*,
Jinbiao Liu
3,
Guoqiang Song
2,
Shuchang Huang
3,*,
Claudia Li
4 and
Jaka Sunarso
4
1
School of Intelligent Materials and New Energy, Institute of Carbon Neutral New Energy, Yuzhang Normal University, Nanchang 330103, China
2
School of Hydraulic and Ocean Engineering, Changsha University of Science & Technology, Changsha 410114, China
3
School of Chemistry and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China
4
Research Centre for Sustainable Technologies, Faculty of Engineering, Computing and Science, Swinburne University of Technology, Jalan Simpang Tiga, Kuching 93350, Sarawak, Malaysia
*
Authors to whom correspondence should be addressed.
Water 2025, 17(22), 3319; https://doi.org/10.3390/w17223319
Submission received: 20 October 2025 / Revised: 16 November 2025 / Accepted: 18 November 2025 / Published: 20 November 2025
(This article belongs to the Section Wastewater Treatment and Reuse)
Browse Figures
Versions Notes

Abstract

The long-distance transport of wastewater in sewers inevitably leads to the formation of biofilms on the inner wall of sewers. Numerous studies have focused on analyzing the hydrogen sulfide, methane production, and emission patterns associated with sewer biofilms in sewer systems. This study employed bibliometric methods to analyze the research progress in the field of sewer biofilms from 1995 to 2025, and revealed the associated development trend, international cooperation network, and research hotspots. The results demonstrate a substantial increase in the number of annual publications over the past decade, with China and Australia as the primary contributors. The journal Water Research has been found to exert a significant influence. The research hotspots concentrate on the generation and control of hydrogen sulfide and methane, sewer corrosion mechanisms, and microbial community dynamics, with chemical dosing, sulfate-reducing bacteria, and biofilm metabolism as the key directions. The evolution of keywords demonstrates that early research focused on organic matter transformation, and in recent years, there has been a shift towards microbial ecology and wastewater epidemiology, along with other emerging areas. Recent years have seen China as well as China’s institution and authors emerge as the primary contributors in the sewer biofilm field, a development attributable to the country’s policy support, which has precipitated the development of green technologies and smart monitoring systems. This study demonstrates the necessity of international cooperation and provides theoretical references and technological directions for future sewer biofilms research.

1. Introduction

Biofilms, as initially observed and proposed by Henrich in 1933 [1], are defined as organized groups of bacteria attached to the surface of animate or inanimate objects, encapsulated by bacterial extracellular macromolecules [2]. The biodiversity of microorganisms and the biodiversity of extracellular polymers in biofilms engender complexity, stability, and functionality [3]. The sewer system constitutes a pivotal component of an urban wastewater management infrastructure, responsible for collecting and transporting wastewater from communities to the wastewater treatment plants (WWTP) before discharge [4]. The transportation of wastewater is dependent on the topography, with transport occurring through either gravity or pressurized mains [5]. During the in-sewer transport, biofilms are developed and attached to the inner wall of sewer systems, inducing significant variations in wastewater characteristics, e.g., organic matter concentration and ammonia nitrogen concentration. This affects the microbial community of biological treatment units within the WWTP [6].
In gravity sewer systems, organic pollutants (e.g., polycyclic aromatic hydrocarbons [7], polychlorinated biphenyls [8], pharmaceuticals [9], personal care products [10], illicit drugs [11]), and inorganic pollutants (e.g., heavy metals [12]), can be stored and concentrated in sewer sediments or biofilms by physical deposition. These contaminants buried in sewer sediments or biofilms, led to the release of odorous compounds (hydrogen sulfide, H2S) and greenhouse gases (methane) [13]. This poses a serious threat to the integrity of sewage pipelines and downstream wastewater treatment systems, presenting significant environmental and health risks [14]. Therefore, numerous studies dedicated the analysis of H2S and methane production and emission patterns. As such, various chemical and biological technologies have been developed to address this issue [4,15,16,17,18,19,20].
Moreover, contaminants accumulated in sewer sediments or biofilms can be reintroduced to the water column via resuspension [21]. These phenomena pose significant challenges to the treatment facilities. Consequently, the in-sewer transformation and migration of contaminants have attracted widespread attention [7,8,9,10,11,12]. A recent review summarized advances in the study of wastewater quality changes during conveyance in sewer systems and processes within sewers [6]. The quality of wastewater in sewers changes due to complex physio-biochemical processes. Many of these processes are spatially and temporally organized. Some exhibit relatively consistent patterns. Notably, pollutants and biofilm microorganisms show covariation across continuous changes in the sewer cross-section.
Current understanding of biofilm in sewage pipes remains extremely limited. Inspired by this gap, this study systematically reviewed existing research literature, employing bibliometric analysis to examine multiple dimensions including disciplinary fields, international research developments, relevant journals, and research hotspots reflected through keyword co-occurrence [22,23]. Bibliometric analyses of extant literature can effectively unearth the associations and patterns hidden in different studies, predicting potential research hotspots and emerging fields. This study aims to (a) reveal the development, scientific collaborations, and key research topics of the sewer biofilms field, (b) deepen the understanding of the field. Overall, this work provides a comprehensive bibliometric review of the sewer biofilms field and clearly demonstrates the contemporary research trends.

2. Methodology

2.1. Data Sources

The literature data analyzed in this study was sourced from the Web of Science Core Collection (WoSCC) database, a multidisciplinary database that enables the retrieval of literature records from around the world [24]. The search was conducted on 4 April 2025, with the search field of ‘All field’ (ALL) and the literature type restricted to article and review article. With search query of “ALL = Wastewater sewer OR urban sewer” and “ALL = Biofilm”, 6671 and 111,353 papers were recorded. Moreover, with the search query of “ALL = ‘Wastewater sewer OR urban sewer’ AND ‘Biofilm’”, 217 papers were retrieved, and all these records were downloaded as plain text files and submitted to CiteSpace v.6.4.R1 software for bibliometric analysis.

2.2. Research Methodology

The utilization of bibliometric software enables scholars to undertake effective analyses of the publication and citation achievements of their peers. This identifies pivotal focal points and emerging trends within the designated field, and elucidate academic collaborations. A visual knowledge mapping software (CiteSpace v.6.4.R1) was employed to convert data obtained from WoSCC into a usable format [25,26]. This study encompassed a time span from 1995 to 2025, with a time-slicing interval of one year. Node types within the software were customized in accordance with specific analysis objectives. The “g-index” value was adjusted to prioritize the most important and relevant projects. The bibliometric analysis performed encompasses a variety of scientific bibliometric parameters, including citation frequency, betweenness centrality, and citation burst [27].

3. Results and Discussion

3.1. Annual Distribution of Literature

Alterations in the quantity of publications can be indicative of the level of academic interest and activity in the pertinent field of study. The number of publications focused on “urban sewer” or “wastewater sewer” included in the WoSCC database in the past three decades is shown in Figure 1a. The number of articles published each year exceeded 400 from 2021 to 2024. Figure 1b shows the number of publications focusing on “biofilm” exhibits an overall growth trend. Thess trends are indicative of the ongoing development and maturation of the associated field. The number of publications involving both “urban sewer or wastewater sewer” and “biofilm” is significantly lower than the number of publications involving “urban sewer or wastewater sewer”. The number of citations of papers related to “urban sewers or sewage pipes” and “biofilms” exceeded 600 in both 2023 and 2024 (Figure 1c). This indicates a paucity of research focusing on biofilms in wastewater sewers a decade ago. This may be attributed to overlooking the significant role and impact of biofilms in wastewater sewer system. However, advances in research techniques over the last decade have led to a greater realization of the sewer biofilms, prompting researchers to conduct more extensive and in-depth studies on biofilms in wastewater networks. This resulted in a substantial increase in the number of publications in the field over the past decade (Figure 1c).

3.2. Source Distribution of Literature

Journals serve as the fundamental medium for scientific communication and dissemination of knowledge. Over the past three decades, research on sewer biofilms has predominantly been published in journals within environmental science and engineering fields. As shown in Table 1, Water Research, Water Science and Technology, and Science of the Total Environment are the top journals with 38, 38, and 27 publications, respectively. Notably, Water Science and Technology published most of its sewer biofilms-related articles before 2010 (30 out of 38), while Water Research and Science of the Total Environment had a majority of their contributions after 2010. This shift reflects evolving publication trends within the field.
Citation analysis reveals that Applied and Environmental Microbiology, despite publishing only three sewer biofilms-related articles, has the highest average citations (59.33), driven by two highly influential studies from 1987 and 2002 [28,29]. Other journals with high citation values (>30) include Water Research (56.82), Science of the Total Environment (41.26), Environmental Science and Technology (38.17), and Environment International (32.67). These globally renowned journals underscore the academic quality and impact of sewer biofilms research, suggesting increased global attention to this field.

3.3. Cooperation Analysis

3.3.1. Collaborative Network Analysis of Countries

Figure 2a shows a network analysis diagram of the collaborating countries in the sewer biofilms field from 1995 to 2025, which contains 39 nodes and 88 collaborations. Obviously, scholars from China (PEOPLES R CHINA) have contributed the most publications to the sewer biofilms field, with a total of 53 publications. The subsequent contributors are Australia (42 publications), the United States (29 publications), Denmark (27 publications), Germany (16 publications), Belgium (14 publications), Spain (11 publications), Switzerland (11 publications), and France (10 publications), in descending order. With regard to centrality, the highest score of 0.49 was attained by China, indicating that China has the closest cooperation with other countries. The following countries are listed in descending order: the United States (0.38), Germany (0.26), Australia (0.24), Switzerland (0.22), Denmark (0.16), Iran (0.13), Spain (0.12), Poland (0.12) and Vietnam (0.12), Scotland (0.12), and France (0.11) and Italy (0.11).
As demonstrated in Figure 2b, although China has the highest bursting strength (9.68), China was active in the sewer biofilms field since 2014, becoming a bursting country in 2023 and maintaining this status to the present day. This finding indicates that China’s scientific influence has undergone a marked increase in recent years. The country with the second highest bursting strength is Denmark, with an intensity value of 7.71. It is noteworthy that Denmark was the first country to burst and continued to be a bursting country over a 15-year period from 1995 to 2009. During this period, Norway (from 1997 to 1998) and Japan (from 1998 to 2006) experienced a brief period of bursting. Subsequently, researchers and academics from the England and Switzerland became active in the sewer biofilms field, emerging as bursting countries in 1999 and 2002, respectively, and continuing as the two bursting countries with the longest duration until 2017 and 2018. During this period, Australia (6 years) and Spain (4 years) became bursting countries for a short period of time. Moreover, no bursting countries emerged between 2018 and 2023, suggesting that countries are equally active in the sewer biofilms field during this period. These results reflect the evolving global research landscape in the sewer biofilms field. Specifically, the most influential countries in the sewer biofilms field had shifted from Europe (Denmark and Norway) and Japan in the late 1990s and early 2000s, to countries such as the England, Switzerland, and Australia in the 00s and 10s of the 21st century, and to China in the 2020s. This phenomenon could be inextricably linked to China’s national policies, national development strategies, and substantial investment in scientific research (e.g., China’s ‘Double First Class’ programme).

3.3.2. Collaborative Network Analysis of Institutions

Figure 3a shows a network analysis diagram of the collaborating institutions in the sewer biofilms field from 1995 to 2025, which contains 228 nodes and 308 collaborations. Obviously, scholars from the University of Queensland have contributed the most publications to the sewer biofilms field, with a total of 33 publications. The subsequent contributors are Aalborg University (19 publications), Swiss Federal Institutes of Technology Domain (11 publications), Tongji University (9 publications), Swiss Federal Institute of Aquatic Science & Technology (9 publications), Universitat de Girona (9 publications), and Xi’an University of Architecture & Technology (9 publications), in descending order. With regard to centrality, the highest score of 0.23 was attained by University of Queensland, and the following institutions are listed in descending order: Swiss Federal Institutes of Technology Domain (0.18), Universitat de Girona (0.18), Centre National de la Recherche Scientifique (0.15), Swiss Federal Institute of Aquatic Science & Technology (EAWAG) (0.09), Aalborg University (0.08), and University of Wollongong (0.08). The results show that these institutions work more closely with other institutions, and that the University of Queensland has the most extensive and close cooperation with other institutions.
As illustrated in Figure 3a, Aalborg University exhibits the highest bursting strength of 7.38 and is the earliest (1995) bursting institution and continued to be bursting institution with a long duration (12 years). This signifies the academic leadership of Aalborg University in the sewer biofilms field from the 1990s to the beginning of the 21st century. The Norwegian University of Science and Technology was the second earliest bursting institution, but the associated bursting strength and duration was relatively limited. The Swiss Federal Institute of Technology Domain was the longest bursting institution, with a duration from 2002 to 2018. The University of Queensland is the bursting institution with the second highest bursting strength of 3.25, with a bursting period from 2019 to 2021. The high bursting strength and the brief duration of University of Queensland may be attributable to the prevalence of the novel Coronavirus (SARS-CoV-2) pandemic. During this period, the implementation of technological solutions for viral surveillance and control was imperative. Some institutions in China, such as Xi’an University of Architecture and Technology, Harbin Institute of Technology, and Tongji University, began to burst in 2022 and 2023, which is in tandem with China’s ‘dual carbon’ policy. Some publications published by these Chinese institutions focused on real-time monitoring and predition of H2S and water quality in sewer systems [30,31,32], and green process for H2S and pollutants control [33,34,35,36]. Therefore, the burst of Chinese institutions may be related to green building and smart city research driven by recent environmental policies in China (e.g., the ‘dual carbon’ goal).

3.3.3. Co-Authorship Analysis

Figure 4a shows a network analysis diagram of the collaborating authors in the sewer biofilms field from 1995 to 2025. In the point of the number of publications, the top three authors who contributed most to the sewer biofilms field are Yuan, Zhiguo (18 publications), Hvitved-Jacobsen, T (11 publications), and Jiang, Guangming (11 publications) (Table 2). Moreover, there is a substantial disparity in the color distribution of the corresponding nodes of the three authors and their collaborative network nodes (Figure 4a). Among them, the author Hvitved-Jacobsen, T, and his collaborating network nodes generally exhibited a blue-green color; the author Yuan, Zhiguo, and his collaborating network nodes generally exhibited a brown color; in contrast, the author Jiang, Guangming, and their collaborating network nodes are more inclined to a dark red color. This finding suggests that the author Hvitved-Jacobsen, T, conducted studies related to sewer biofilms in the 1900s, while the author Yuan, Zhiguo, and Jiang, Guangming, were active in research related to this field in the 2010s. Correspondingly, as illustrated in Figure 4a, the author Hvitved-Jacobsen, T, is one of the authors with the strongest citation bursts, with a bursting strength of 4.48, bursts beginning in 1998 and ending in 2006; Yuan, Zhiguo, exhibits the highest bursting strength of 6.74, with a bursting duration of 9 years (from 2013 to 2021). These characteristics signify the academic leadership of Hvitved-Jacobsen, T, and Yuan, Zhiguo, in the sewer biofilms field.

3.4. Co-Citation Analysis

3.4.1. Author Co-Citation Analysis

A significant function of CiteSpace software is co-citation analysis. When two articles are cited together, these two articles are designated co-cited articles. Co-citation analysis has the capacity to provide a more quantitative reflection of the knowledge bases, research hotspots, and trends. By co-citation analysis, the author co-citation network with 274 nodes and 1090 links was obtained, as illustrated in Figure 5a. Regarding the co-occurrence analysis, HVITVED-JACOBSEN T. and JIANG G.M. are the prominent cited authors, with a total co-citation frequency of 52 and 47 (Table 3), respectively. Top 15 authors in co-citation frequency, centrality, and burst strength are shown in Table 3. HVITVED-JACOBSEN T. has the highest frequency of co-citation, followed by JIANG G.M., GUTIERREZ O., ZHANG L., and GUISASOLA A. As for the centrality, HVITVED-JACOBSEN T., NIELSEN P.H., AUGUET O., AESOY A., and ZHANG L. are the top five authors. Moreover, the authors with higher value of burst strength are ZUO ZQ, JIN PK, HENZE M., HVITVED-JACOBSEN T., and GAO J.F. (Figure 5b). The results indicate that these authors have played a larger and longer role in the area of biofilm in wastewater sewers. Keeping track of these authors’ research could make researchers easier to acquire knowledge and identify future trends in the sewer biofilms field. Moreover, among these authors, the co-citation frequency, centrality, and bursting strength of HVITVED-JACOBSEN T. are all relatively high, indicating that HVITVED-JACOBSEN T.’s research results have been recognized and studied by many scholars. As a cornerstone of the current development in the field of sewer biofilms, his work not only has promoted the field to the present but will continue to have an impact in the future.

3.4.2. Document Co-Citation Analysis

The top five most highly co-cited publications in biofilm in wastewater sewers are illustrated in Table 4. Three of these co-cited publications are research article covering model simulation studies on biomarkers transformation in real sewers [37], mechanistic studies on H2S and methane control [38], and microbial community distribution and organics metabolism [39]. The other two co-cited publications are a book and a review paper, both focusing on sewer biofilms. It is noteworthy that the author of the book (Hvitved-Jacobsen T) was the second contributor for publications in the field (Table 2) and the top two co-author in bursting strength (Figure 4b). This indicates that this author has been very productive in basic research in the field and has laid a deep foundation for scientific research in the field.
It is clear that the top five most frequently co-cited publications are among the top 15 references with the strongest citation bursts (Figure 6), suggesting that the research topics of these publications may all be important directions in the sewer biofilms field. Moreover, two-thirds of the 15 publications were from the journals Water Research and Environmental Science & Technology, which is consistent with their robust presence in the environmental field and reflects the international interest in the sewer biofilms field. Furthermore, approximately half of the top 15 references with the strongest citation bursts were published in 2018 and 2019, and they began to burst two or three years later. This suggests that these publications have had an impact on the sewer biofilms field and that research on sewer biofilms continues to grow in popularity.

3.5. Co-Word Analysis

3.5.1. Keywords Co-Occurrence Analysis

To capture current research focal points in the sewer biofilms field, the co-occurrence of collected keywords in the literature was analyzed. The time range was set from 1995 to 2025, and the time slice was set to 1 year for visualization. As shown in Figure 7, “waste water” (34), “biofilm” (22), “hydrogen sulfide” (18), “activated sludge” (17), “removal” (16), “sulfide” (15), “corrosion” (12), “bacteria” (11), “methane production” (11), “transformation” (10), and “organic matter” (10) are the most frequently occurring keywords. This indicates that the transformation and control of H2S and methane in sewer systems, which would cause sewer corrosion, is a topic of significant concern for researchers. In-depth investigation into the associated mechanisms can provide a solid foundation for designing and operating effective sewage systems. Moreover, “activated sludge”, “removal”, and “sediment” have a high frequency of occurrence. These keywords are of paramount importance in any research related to this field. Furthermore, the majority of the nodes exhibit a skewing towards dark red, as opposed to dark blue, which can be attributed to the preponderance of relevant studies that were primarily published in the last decade.

3.5.2. Keywords Clustering Analysis

To explore the relationships among the co-occurring keywords and outline the various hot sub-domains in the sewer biofilms field, keyword cluster analysis was performed. As shown in Figure 8a, 12 topic clusters were obtained: sewer corrosion (#0), methane production (#1), sulfate-reducing bacteria (#2), nitrate (#3), sewer sediments (#4), pharmaceuticals (#5), in-sewer degradation (#6), suspended sediment (#7), free nitrous acid (#8), activated sludge (#9), chemical dosing (#10), and activated sludge model 3 (asm 3, #11). In cluster analysis, two metrics, namely modularity (Q) and weighted mean silhouette (S), are of particular significance in determining the validity of the clustering results. In this study, the Q value of 0.7549 (greater than 0.3) and the S value of 0.9086 (greater than 0.7) suggests that the cluster structure is significant, reasonable, and convincing [42]. As illustrated in Figure 8a, there exists a degree of overlap among the various clusters, indicating that the pertinent research themes within the domain of sewer biofilms are not entirely isolated. Consequently, a particular study may encompass multiple research themes.
Sewer corrosion is one of the significant research topics in the sewer system field [43,44]. Cluster #0 of sewer corrosion exhibits a certain degree of overlap with clusters #2 and #6, which can be attributed to the corrosion of sewer initiated by the formation of aqueous H2S [45]. The generation and accumulation of H2S are closely associated with the growth and metabolism of microorganisms within the sewer systems, particularly sulfate-reducing bacteria, which is the topic of cluster #2. Moreover, sewer corrosion adversely affects the entire wastewater collection and treatment system, and imposes a significant economic burden, with annual costs for maintaining and repairing sewer systems damaged by corrosion amounting to USD 200 million in Los Angeles reported by Hewayde et al. [46]. Therefore, numerous studies have been devoted to developing strategies for enhancing concrete durability and corrosion resistance. Among these, chemical dosing represents a significant approach, which employs a float equipped with a spray head to uniformly distribute chemical solutions onto sewer crowns to neutralize sulfide-oxidizing microorganisms (SOM) and inhibit their regrowth [5,47,48,49]. Therefore, the cluster #10 of chemical dosing also overlaps with cluster #0 (Figure 8a).
The production, transformation, and control of H2S and methane is another significant research topic in the sewer system field [4,50,51]. This topic encompasses both cluster #1 and cluster #2, which exhibit significant overlap with other clusters. This overlap underscores the enthusiasm among scholars for investigating the production, transformation, and control of H2S and methane within the sewer system domain. Additionally, clusters #7 and #11 are completely separate from those of other modules. This separation may be attributed to the relatively weak connection between the activated sludge model and suspended sediments within the sewer system, which is not the primary focus of research on sewer biofilms.
Furthermore, the timeline graph of the cluster analysis provides a more intuitive observation of the chronological sequence in which different co-occurrence keywords appear within various cluster modules. As illustrated in Figure 8b, the co-occurring keywords associated with cluster #0 predominantly emerged between 1995 and 2000. Notably, the overall duration of this cluster extends only until 2020, suggesting that the research topic of sewer corrosion is more classical in nature and falls within the realm of basic research. The emergence of co-occurring keywords in other clusters appears to be relatively dispersed over time, which may be related to the continuous progress in the level of scientific and technological research on an international scale and the increasing research enthusiasm of researchers in recent decades. During this process, novel research perspectives and technological approaches have been incorporated into the study, thereby facilitating a more profound comprehension of the enigmatic nature of pipeline biofilms and enhancing the efficacy of engineering practice. Furthermore, the comparatively brief duration of clusters #7 and #11, in conjunction with the diminutive size of the nodes within these clusters, indicates that these two themes of suspended sediment and activated sludge model are not demonstrably associated with sewer biofilms. This finding is in alignment with the complete separation of these two clusters from other clusters (Figure 8a).

3.5.3. Keywords Evolution Analysis

The frequency of appearance of keywords within a certain period can reflect the research focal points of that period, which aids in identifying research frontiers [27]. Figure 9 demonstrates that “organic matter” emerged for the first time with a strength of 4.78 and persisted for two years from 1998 to 2000. This phenomenon bears a striking resemblance to the sudden surge in the number of papers in the field of biofilms in downspouts that was observed in 1998. However, no new keywords appeared for a considerable period thereafter. It was not until 2009 that a new bursting keyword (hydrogen sulfide) appeared, which is related to the sudden increase in the number of publications in 2009 (Figure 1c). Combined with the temporal characteristics of the other co-occurring keywords and the number of publications during this period (Figure 9), it can be deduced that the primary focus prior to 2009 was on the fundamental studies, such as the transformation of organic matter and H2S in sewer systems. In the subsequent decade, different bursting keywords, such as “hydrogen sulfide”, “pharmaceuticals”, “methane production”, “free nitrous acid”, and “degradation” gradually emerged (Figure 9). This finding suggests that research into sewer biofilms underwent a period of gradual deepening during this time, while new research perspectives continued to be introduced into the field. In recent years, the advent of the bursting keyword of the microbial community could be indicative of the advancement of microbial ecology technologies in the domain of sewer biofilms. Furthermore, the emergence of “wastewater-based epidemiology” and “biomarkers” may be associated with the necessity for viral surveillance technologies during the SARS-CoV-2 pandemic.

4. Conclusions

This study conducted a systematic review of the literature on sewer biofilms in sewer systems. According to a bibliometric analysis, the number of publications on biofilm-related research has increased significantly, particularly with regard to analyzing microbial community structure and function. This highlights the growing academic interest in biofilm applications, particularly within wastewater treatment systems. The findings revealed a substantial increase in research activity over the past decade, with China, Australia, United States, and Denmark being the primary contributors to this growth. The control of H2S and methane, the mechanisms of sewer corrosion and microbial metabolism are ongoing challenges, with techniques such as chemical dosing becoming a primary control tool. Moreover, the evolution of keywords demonstrates that research has expanded from early organic matter transformation to microbial community analysis and wastewater epidemiological applications, reflecting technological advances and changing needs. China has emerged as a significant research force, propelled by ‘dual-carbon’ policies that have catalyzed the development of green processes and real-time monitoring technologies. The international co-operation network under scrutiny reveals the pre-eminence of European countries in the field, whilst concomitantly highlighting the increased influence of China in recent years. In the future, there is a necessity to deepen our understanding of microbial metabolic mechanisms, smart control technologies, and multi-pollutant synergies in order to address the sustainability challenges of sewer systems. This study provides a reference point for academics in the evolution and frontiers of hot trends in sewer biofilms field, which in turn can help optimize wastewater treatment systems and protect the environment.

Author Contributions

Conceptualization, L.Z.; methodology, L.Z.; software, L.Z.; formal analysis, L.Z., S.H.; investigation, L.Z.; resources, L.Z.; data curation, L.Z., S.H.; writing—original draft preparation, L.Z.; writing—review and editing, J.L., G.S., S.H., C.L. and J.S.; visualization, L.Z.; All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

No new data were created or analyzed in this study.

Conflicts of Interest

The authors declare no conflicts of interest.

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Water 17 03319 g001
Figure 1. Number of annual publications related to (a) “wastewater sewer or urban sewer” and (b) “biofilm”, and (c) number of annual publications and citations related to “wastewater sewer or urban sewer” AND “biofilm”. The data was retrieved from the WoSCC database on 4 April 2025.
Figure 1. Number of annual publications related to (a) “wastewater sewer or urban sewer” and (b) “biofilm”, and (c) number of annual publications and citations related to “wastewater sewer or urban sewer” AND “biofilm”. The data was retrieved from the WoSCC database on 4 April 2025.
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Figure 2. (a) Network analysis diagram of the collaborating countries in the sewer biofilms field from 1995 to 2025 and (b) top eight countries with the strongest citation bursts.
Figure 2. (a) Network analysis diagram of the collaborating countries in the sewer biofilms field from 1995 to 2025 and (b) top eight countries with the strongest citation bursts.
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Figure 3. (a) Network analysis diagram of the collaborating institutions in the sewer biofilms field from 1995 to 2025 and (b) top 11 institutions with the strongest citation bursts.
Figure 3. (a) Network analysis diagram of the collaborating institutions in the sewer biofilms field from 1995 to 2025 and (b) top 11 institutions with the strongest citation bursts.
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Figure 4. (a) Network analysis diagram of the collaborating authors in the sewer biofilms field from 1995 to 2025 and (b) top 11 authors with the strongest citation bursts.
Figure 4. (a) Network analysis diagram of the collaborating authors in the sewer biofilms field from 1995 to 2025 and (b) top 11 authors with the strongest citation bursts.
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Figure 5. (a) Network analysis diagram of the co-cited authors in the sewer biofilms field from 1995 to 2025 and (b) top 17 cited authors with the strongest citation bursts.
Figure 5. (a) Network analysis diagram of the co-cited authors in the sewer biofilms field from 1995 to 2025 and (b) top 17 cited authors with the strongest citation bursts.
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Figure 6. Top 15 references with the strongest citation bursts.
Figure 6. Top 15 references with the strongest citation bursts.
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Figure 7. Co-occurring keyword analysis of publications related to the sewer biofilms field from 1995 to 2025.
Figure 7. Co-occurring keyword analysis of publications related to the sewer biofilms field from 1995 to 2025.
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Figure 8. (a) Clustering analysis and (b) timeline map of co-occurring keyword of publications related to sewer biofilms field.
Figure 8. (a) Clustering analysis and (b) timeline map of co-occurring keyword of publications related to sewer biofilms field.
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Figure 9. Top 15 keywords with the strongest citation bursts.
Figure 9. Top 15 keywords with the strongest citation bursts.
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Table 1. Top 15 journals with the most publications related to sewer biofilms.
Table 1. Top 15 journals with the most publications related to sewer biofilms.
No.SourcePublicationsCitationsAverage CitationIF (2023)
1Water Research38215956.8211.5
2Water Science and Technology3893224.532.3
3Science of the Total Environment27111441.268.2
4Journal of Hazardous Materials712017.1412.2
5Environmental Science Technology622938.1710.9
6Chemical Engineering Journal59418.8013.4
7Water Environment Research48020.002.5
8Applied And Environmental Microbiology317859.333.9
9Environment International39832.6710.3
10Water Air and Soil Pollution333113.8
11Biochemical Engineering Journal3299.673.7
12Environmental Pollution32487.6
13Journal of Environmental Engineering31861.6
14Environmental Technology31242.2
15npj Clean Water320.6710.5
Table 2. Top authors (publications >5) with the most publications related to sewer biofilms.
Table 2. Top authors (publications >5) with the most publications related to sewer biofilms.
No.AuthorsNumber of PublicationsCentrality
1Yuan, Zhiguo180.02
2Hvitved-Jacobsen, T110.01
3Jiang, Guangming110.01
4Gutierrez, Oriol50.00
5Li, Jiaying50.01
6Nielsen, PH50.00
Table 3. Top 15 authors in co-citation frequency, centrality, and burst strength.
Table 3. Top 15 authors in co-citation frequency, centrality, and burst strength.
No.FrequencyCentralityBursting Strength
1HVITVED-JACOBSEN T. (52)HVITVED-JACOBSEN T. (0.30)Zuo Z.Q. (6.39)
2JIANG G.M. (47)NIELSEN P.H. (0.25)JIN P.K. (5.55)
3GUTIERREZ O. (31)AUGUET O. (0.12)HENZE M. (5.36)
4ZHANG L. (29)AESOY A. (0.12)HVITVED-JACOBSEN T. (5.09)
5GUISASOLA A. (28)ZHANG L. (0.1)GAO J.F. (5.05)
6GANIGUE R. (24)CAO Y.S. (0.1)LI W.K. (4.82)
7MOHANAKRISHNAN J. (21)GANIGUE R. (0.09)LI J.Y. (4.41)
8NIELSEN P.H. (21)HENZE M. (0.09)OKABE S. (4.33)
9LIU Y.W. (19)JIANG G.M. (0.08)BJERRE H.L. (4.26)
10HENZE M. (19)LI J.Y. (0.08)LIU Y.W. (4.25)
11AUGUET O. (19)JIN P.K. (0.07)AUGUET O. (4.22)
12JIN P.K. (18)BOON A.G. (0.07)YONGSIRI C. (4.11)
13ZUO Z.Q. (16)ALMEIDA M.C. (0.07)THAI P.K. (3.86)
14VOLLERTSEN J. (16)AHMED W. (0.06)SHI X. (3.85)
15LI J.Y. (16)MOHANAKRISHNAN J. (0.05)CHOI P.M. (3.82)
Table 4. Top five most highly co-cited publications in the sewer biofilms field.
Table 4. Top five most highly co-cited publications in the sewer biofilms field.
No.TitleJournalFrequencyYearReference
1Stability of Illicit Drugs as Biomarkers in Sewers: From Lab to RealityEnvironmental Science & Technology102018[37]
2Sewer Processes—Microbial and Chemical Process Engineering of Sewer NetworksBoca Raton (Book)102013[40]
3Different ferric dosing strategies could result in different control mechanisms of sulfide and methane production in sediments of gravity sewersWater Research102019[38]
4Co-Variation between Distribution of Microbial Communities and Biological Metabolization of Organics in Urban Sewer SystemsEnvironmental Science & Technology92018[39]
5Current status and future prospects of sewer biofilms: Their structure, influencing factors, and substance transformationsScience of Total Environment92019[41]
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Zhang, L.; Liu, J.; Song, G.; Huang, S.; Li, C.; Sunarso, J. Recent Advances in Sewer Biofilms: A Perspective on Bibliometric Analysis. Water 2025, 17, 3319. https://doi.org/10.3390/w17223319

AMA Style

Zhang L, Liu J, Song G, Huang S, Li C, Sunarso J. Recent Advances in Sewer Biofilms: A Perspective on Bibliometric Analysis. Water. 2025; 17(22):3319. https://doi.org/10.3390/w17223319

Chicago/Turabian Style

Zhang, Linjun, Jinbiao Liu, Guoqiang Song, Shuchang Huang, Claudia Li, and Jaka Sunarso. 2025. "Recent Advances in Sewer Biofilms: A Perspective on Bibliometric Analysis" Water 17, no. 22: 3319. https://doi.org/10.3390/w17223319

APA Style

Zhang, L., Liu, J., Song, G., Huang, S., Li, C., & Sunarso, J. (2025). Recent Advances in Sewer Biofilms: A Perspective on Bibliometric Analysis. Water, 17(22), 3319. https://doi.org/10.3390/w17223319

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