Chemical methods to remove microplastics from wastewater: A review.

Microplastics (Mps) have emerged as a pervasive environmental concern, with their presence detected not only in freshwater ecosystems but also in drinking and bottled water sources. While extensive research has centered on understanding the origins, migration patterns, detection techniques, and ecotoxicological impacts of these contaminants, there remains a notable research gap about the strategies for Mps removal. This study reviews existing literature on chemical approaches for mitigating microplastic contamination within wastewater systems, focusing on coagulation precipitation, electrocoagulation, and advanced oxidation methods. Each approach is systematically explored, encompassing their respective mechanisms and operational dynamics. Furthermore, the comparative analysis of these three techniques elucidates their strengths and limitations in the context of MPs removal. By shedding light on the intricate mechanisms underlying these removal methods, this review contributes to the theoretical foundation of microplastic elimination from wastewater and identifies future research trajectories and potential challenges.

Mechanism underlying the sustained stimulatory effects of energization on biomethane recovery from food waste post-energization cessation.

Microbial electrolysis cell-assisted anaerobic digestion represents a promising approach for enhancing methanogenesis. This study investigated the impact of varying energy levels followed by long-term open circuit on biogas recovery from food waste. The results demonstrated that a mild voltage of 0.4 V resulted in 61.7% increase in methane yield, with a methane composition reaching 78.89% vol and a remarkable reduction in digestion time by 8 days. Additionally, the facilitated effects remained after prolonged periods of open-circuit. In-depth study revealed that energization significantly enhanced organic hydrolysis, redox proteins secretion and sludge electro-activity. Microbial communities showed that the ever-present energization enriched the hydrolytic bacterium and electrophiles. Subsequent investigations also revealed the upgradation of enzyme-encoding genes associated with hydrolysis and the synthesis of flavin and its homologs (i.e. ribE, ssuE and nfrA2). These findings collectively demonstrated the enduring benefits of energization were linked to the enhanced hydrolysis and regulated mediator-mediated electron transfer pathway.

Immobile Iron-Rich Particles Promote Arsenic Retention and Regulate Arsenic Biotransformation in Treatment Wetlands.

Remediation of arsenic (As)-contaminated wastewater by treatment wetlands (TWs) remains a technological challenge due to the low As adsorption capacity of wetland substrates and the release of adsorbed As to pore water. This study investigated the feasibility of using immobile iron-rich particles (IIRP) to promote As retention and to regulate As biotransformation in TWs. Iron-rich particles prepared were immobilized in the interspace of a gravel substrate. TWs with IIRP amendment (IIRP-TWs) achieved a stable As removal efficiency of 63 ± 4% over 300 days, while no As removal or release was observed in TWs without IIRP after 180 days of continuous operation. IIRP amendment provided additional adsorption sites and increased the stability of adsorbed As due to the strong binding affinity between As and Fe oxides. Microbially mediated As(III) oxidation was intensified by iron-rich particles in the anaerobic bottom layer of IIRP-TWs. Myxococcus and Fimbriimonadaceae were identified as As(III) oxidizers. Further, metagenomic binning suggested that these two bacterial taxa may have the capability for anaerobic As(III) oxidation. Overall, this study demonstrated that abiotic and biotic effects of IIRP contribute to As retention in TWs and provided insights into the role of IIRP for the remediation of As contamination.

Bibliometric evaluation of 2000-2019 publications on functional near-infrared spectroscopy.

This study aimed to explore and analyze research trends and frontiers on functional near-infrared spectroscopy (fNIRS) in the past 20 years and identify collaboration networks. fNIRS-related publications from 2000 to 2019 were retrieved from the Web of Science database. A total of 1727 publications satisfied the search criteria. Bibliometric visualization analysis of active authors, journals, institutions, countries, references, and keywords were conducted. The number of annual related publications remarkably increased over the years. Fallgatter published the largest number of fNIRS-related papers (83). Neuroimage not only had the largest number of papers published in the first 10 journals (157 articles) but also had the highest impact factor (IF, 2018 â€‹= â€‹5.812). The University of Tubingen had the highest number of fNIRS-related publications in the past 20 years. The United States ranked first in terms of comprehensive influence in this field. In recent years, burst keywords (e.g., infant, social interaction, and older adult) and a series of references with citation burst provided clues on research frontiers.

Primary sludge as solid carbon source for biological denitrification: System optimization at micro-level.

Commercial carbon source (e.g. methanol) has been frequently used to enhance heterotrophic denitrification for nitrate removal. However, this is not sustainable due to the high cost of chemical purchasing and excessive sludge production. To address these issues, this study reports an integrated denitrification system using primary sludge as solid carbon source. Complete denitrification without any nitrite accumulation achieved at the primary sludge dosage of 6.0 g VSS/g N with the maximum specific nitrate reduction rate of 6.4 mg N/g VSS/h, which was comparable with the reported soluble carbon source. More importantly, as a solid "waste" in municipal wastewater treatment plants (WWTPs), the primary sludge was simultaneously reduced by 65.3%-85.1%, and this avoids the intensive denitrification biomass generation that generally occurs in using the commercial carbon source. Ammonium, phosphate, and recalcitrant organic matter were released meantime. Interestingly, the concentration of ammonium and phosphate declined during the denitrification process. The refractory dissolved organics mainly composed of aromatic protein and microbial by-products. The detailed cycle study suggests that an appropriate denitrification cycle/duration time would largely lower the effluent organics concentration, which can be achieved by monitoring the pH turning point. This study clearly demonstrates that primary sludge is a promising alternative carbon source for biological denitrification with great economic benefits and environmental sustainability.

Near-infrared reflectance spectroscopy for rapid prediction of biochemical methane potential of wastewater wasted sludge.

The information of biochemical methane potential (BMP) of wasted sludge is essential to ensure the stable operation of sludge management processes. However, conventional anaerobic digestion (AD) approach for BMP test is time-consuming and labour-intensive. Currently, the technique of Near Infrared Spectroscopy (NIRS) is gaining prominence in the biogas production within AD process. Previous studies mostly focused on predicting BMP values for fibrous plant biomass and solid waste, with only a limited number of studies attempting to apply NIRS to obtain BMP values across a wide array of wasted sludge types. To obtain BMP values for this diverse range of wasted sludge efficiently and accurately, it is imperative to develop precise models for assessing BMP values using NIRS. In this study, the possibility of using NIRS to predict the BMP values of wasted sludge was evaluated. A total of 70 sludge samples from different sources were investigated to develop a BMP-prediction model by correlating the measured BMP values with the obtained NIR spectra. As a result, a reliable and successful BMP-prediction model was established with the determination coefficient of 0.90, residual prediction deviation of 3.50 and low root mean square error of prediction of 36.8 mL CH4/g VS. This BMP-prediction model is satisfactory for predicting BMP values of various types of sludge. It could provide support for plant operators to make decisions rapidly, thereby improving the process efficiency and optimizing sludge management procedures.

Redistribution of perfluorooctanoic acid in sludge after thermal hydrolysis: Location of protein plays a major role.

Perfluorinated compounds (PFCs) are a group of bio-recalcitrant pollutants that remain in waste activated sludge and may subsequently be transferred with sludge to thermal hydrolysis pretreatment (THP) process. Instead of reduction, it is observed previously that the concentration of free PFCs elevated after THP. By employing perfluorooctanoic acid (PFOA) as a representative, this study developed a hierarchical scheme to pinpoint the key factors that contribute to free PFOA elevation from the complex sludge transformations. According to the results, the relative abundance of PFOA in the liquid phase increased by 11.7 - 22.9% during THP. In the solid phase, the amide groups reduction and the spatial structure change of proteins weakened the sorption capability of solids for PFOA. In the liquid phase, the increase of proteins, which could bind and form static hindrance to regulate the behavior of PFOA, was the main factor to retain PFOA in liquid. In contrast, other sludge transformations including changes in pH, zeta potential, ionic condition and specific surface area, displayed insignificant impact on the redistribution process. The study presents a detailed picture on how sludge transformations would regulate PFCs distribution that ultimately direct the selection of further treatment processes.

Effects of sludge thermal hydrolysis pretreatment on anaerobic digestion and downstream processes: mechanism, challenges and solutions.

Thermal hydrolysis pretreatment (THP), as a step prior to sludge anaerobic digestion (AD), is widely applied due to its effectiveness in enhancing organic solids hydrolysis and subsequent biogas productivity. However, THP also induces a series of problems including formation of refractory compounds in THP cylinder, high residual ammonia and organic in the AD centrate, inhibition on downstream nitrogen removal process and reduction in UV-disinfection effectiveness during post-treatment. More attention should be paid on how to mitigate these negative effects. Despite intensive studies were carried out to reduce refractory compounds formation and enhance biological performance, there is limited effort to discuss the solutions to tackle the THP associated problems in a holistic manner. This paper summarizes the solutions developed to date and analyzes their technology readiness to assess application potential in full-scale settings. The content highlights the limitations of THP and proposes potential solutions to address the technological challenges.

Mitigation of inhibitory effect of THP-AD centrate on partial nitritation and anammox: Insights into ozone pretreatment.

Anaerobic digestion centrate produced from thermal hydrolysis pretreated sludge (THP-AD centrate) has serious inhibitory effect on ammonium oxidizing bacteria (AOB) and anammox bacteria. This imposes huge challenge to employ partial nitritation/anammox (PN/A) process to treat THP-AD centrate. This study, for the first time, presented an effective strategy, ozone pretreatment, to alleviate such inhibitory effect. The activities of AOB and anammox bacteria increased with increasing ozone dosage, which were likely related to the transformation of organic compounds including humic acid-like and fulvic acid-like substances as well as high molecular weight (HMW) protein. Long-term operation of PN/A system further demonstrated the improved performance in term of nitrogen removal, organics degradation as well as sludge settleability and effluent solids. Nitrogen removal rate (NRR) of 0.64 Kg N/m3/d was achieved (1.38 g O3/ g COD), which was 42.2% higher compared to treating untreated THP-AD centrate. Effluent nitrate, the by-product of PN/A process, was reduced by 39.7% despite of its release in ozonation. This was due to the enhanced denitrification activity, humic acid-like and fulvic acid-like substances as well as HMW protein were significantly reduced. Overall, this study provides a promising method to improve PN/A performance and final effluent quality when treating organic-rich THP-AD centrate.

Cross-sectional study of gender differences in physical activity-related injuries amongst Chinese college students majoring in rehabilitation.

The main objective of the paper was to explore the potential risk factors for physical activity-related injuries (PARI) amongst college students majoring in rehabilitation and to analyse gender differences. A random whole group sampling method was used to recruit freshmen to seniors aged 15-25 years from over 90 universities in China that offer rehabilitation. The total number of people included was 6,032, of which 1,989 were male and 4,043 were female. The underlying risk factors for PARI of different genders were assessed using a structured self-management questionnaire including sociodemographic characteristics, physical activity levels, risk-taking and protective behaviors, and PARI. Totally 6,032 questionnaires were obtained for final analysis, with 792 total number of injured persons (415 males, 377 females), the sum of the cumulative frequency of injuries to injured persons is 1,607 (881 males, 726 females) and a PARI risk of 0.27 (males: 0.44, females: 0.18; p < 0.001; sum of the cumulative frequency of injuries/total number of people surveyed/year). For male and female students, participation in sports teams, having a high level of PA as well as with antisocial behavior were risk factors for developing PARI. Regarding female students, regional differences was associated with elevated odds to suffer from PARI. The prevalence rates of PARI vary between male and female students. The research subjects were university students in rehabilitation. Compared to general college students, rehabilitation students have a certain knowledge base related to injuries, which defines the specificity and research value of this subjects. This study provides guidance for reducing PARI in students in rehabilitation and may provide a basis for developing future injury prevention mechanisms for university students in general.

Effect of different weekly frequencies of Chen-style Tai Chi in elders with chronic non-specific low back pain: study protocol for a randomised controlled trial.

BACKGROUND: Tai Chi (TC), as one of mild to moderate exercise therapies specifically recommended by clinical practice guideline from the American College of Physician, is a viable option for chronic non-specific low back pain (CNLBP) treatment. Nevertheless, limited studies focused on the effect of different weekly frequencies of TC in elders with CNLBP. This superiority study aims to compare the differences of TC with different weekly frequencies in elders with CNLBP on the premise of proving its effectiveness, and identifying whether mindfulness mediates the effect of TC on treatment outcomes. METHODS: In total, 284 senior citizens with CNLBP will be recruited in this single-centre, randomised, single-blinded (outcome assessors, data managers and the statistician), parallel controlled trial. Participants will be randomly divided into either one of three TC groups (1, 3, or 5 sessions/week, on the basis of weekly health educational lectures) or weekly health educational lectures, sustaining for 12 weeks, followed by 12 weeks of follow-up after the end of intervention. The primary outcome (the changes of LBP intensity at rest) will be measured at baseline before randomisation and immediately after the completion of weeks 4, 8 and 12 of the intervention, and the end of follow-up (week 24) using the visual analogue scale (VAS, 0-10 cm) to put a mark on the VAS scale to show how severities of their average low back pain have been over the past 24 h. Secondary outcomes, including Beck Depression Inventory-II, Pain Catastrophising Scale and Five Facet Mindfulness Questionnaire, Oswestry Disability Index and Short Form-36, will be measured at baseline and immediately after the completion of week 12 of the intervention and end of follow-up. The intention-to-treat and per-protocol principles will be used to analyse outcomes with a setting at α = 0.05 as statistical significance. DISCUSSION: This comprehensive and detailed protocol will be the first trial to compare the effectiveness of different weekly frequencies of TC in elders with CNLBP. The outcomes may provide valuable data about the choice of the ideal number of sessions to further normalise the application of exercise for clinicians. TRIAL REGISTRATION: Chinese clinical trial registry ChiCTR2200058190 . Registered on 1 April 2022.

Prevalence and Associated Factors of Complains on Depression, Anxiety, and Stress in University Students: An Extensive Population-Based Survey in China.

Mental health issues are becoming increasingly prevalent amongst university students. However, research on the psychological profile of the general university population is relatively limited. Thus, this study analyses the current state of university students' psychological conditions; the demographic differences in depression, anxiety, and stress and the influencing factors. The objectives are to provide additional appropriate guidance in mental health for university students with different demographic characteristics. A cross-sectional study of 6,032 university students nationwide was conducted from October 2020 to January 2021. A randomized whole-group sampling method was used to select the study participants, and the 21-item Depression, Anxiety, and Stress Scale (DASS) was used. P < 0.05 in the final model were considered statistically significant. The number of university students with no complain of depression, anxiety, or stress was 3,751 (62.2%). The odds of developing complain of depression were higher amongst anxious respondents (AOR = 23.417, 95% CI: 19.706, 27.826) and senior year (AOR = 2.210, 95% CI: 1.657, 2.947) than their counterparts. Students with "myopia" were 1.263 times more likely to be anxious (AOR = 1.263, 95% CI: 1.042-1.530). In terms of "impaired" or not, impaired is defined as any injury, such as sprain, strain, and fracture, "impaired" university students were 1.321 times more likely to be anxious (AOR = 1.321, 95% CI: 1.064-1.641). Furthermore, history of impairment and myopia increased the odds of stress by 1.305 (AOR = 1.305, 95% CI: 1.022-1.667) and 1.305 (AOR = 1.305, 95% CI: 1.012-1.683), respectively. Myopia, physical-activity-related injury (PARI) and irrational eating habits are risk factors for complain of anxiety and stress. Males, upper grades, low parental education, and irrational eating habits are risk factors for complain of depression. Low physical activity levels are also an influential factor for complain of depression. DASS consists of interchangeable risk factors and multiple complains of DASS may coexist.

Characterization of arsenic-metabolizing bacteria in an alkaline soil.

Arsenite (As(III)) is more toxic, mobilizable and bioavailable than arsenate (As(V)). Hence, the transformations between As(III) and As(V) are crucial for the toxicity and mobility of arsenic (As). However, As transformation and microbial communities involved in alkaline soils are largely unknown. Here we investigate two major pathways of As transformation, i.e., As(III) oxidation and As(V) reduction, and identify the bacteria involved in the alkaline soil by combining stable isotope probing with shotgun metagenomic sequencing. As(III) oxidation and significant increase of the aioA genes copies were observed in the treatments amended with As(III) and NO3-, suggesting that As(III) oxidation can couple with nitrate reduction and was mainly catalyzed by the microorganisms containing aioA genes. As(V) reduction was detected in the treatments amended with As(V) and acetate where the abundance of arrA gene significantly increased, indicating that microorganisms with arrA genes were the key As(V) reducers. Acidovorax, Hydrogenophaga, and Ramlibacter were the putative nitrate-dependent As(III) oxidizers, and Deinococcus and Serratia were the putative respiratory As(V) reducers. These findings will improve our understanding of As metabolism and are meaningful for mapping out bioremediation strategies of As contamination in alkaline environment.

Effects of repetitive transcranial magnetic stimulation on neuropathic pain: A systematic review and meta-analysis.

Neuropathic pain (NP) is a chronic pain condition caused by lesion or disease of the somatosensory nervous system. Repetitive transcranial magnetic stimulation (rTMS) is a neuroregulatory tool that uses pulsed magnetic fields to modulate the cerebral cortex. This review aimed to ascertain the therapeutic effect of rTMS on NP and potential factors regulating the therapeutic effect of rTMS. Database search included Web of Science, Embase, Pubmed, and Cochrane Library from inception to July 2021. Eligible studies included randomized controlled studies of the analgesic effects of rTMS in patients with NP. Thirty-eight studies were included. Random effect analysis showed effect sizes of -0.66 (95 % CI, -0.87 to -0.46), indicating that real rTMS was better than sham condition in reducing pain (P < 0.001). This comprehensive review indicated that stimulation frequency, intervention site, and location of lesion were important factors affecting the therapeutic effect. The findings of this study may guide clinical decisions and future research.

Vanadate reducing bacteria and archaea may use different mechanisms to reduce vanadate in vanadium contaminated riverine ecosystems as revealed by the combination of DNA-SIP and metagenomic-binning.

Vanadium (V) is a transitional metal that poses health risks to exposed humans. Microorganisms play an important role in remediating V contamination by reducing more toxic and mobile vanadate (V(V)) to less toxic and mobile V(IV). In this study, DNA-stable isotope probing (SIP) coupled with metagenomic-binning was used to identify microorganisms responsible for V(V) reduction and determine potential metabolic mechanisms in cultures inoculated with a V-contaminated river sediment. Anaeromyxobacter and Geobacter spp. were identified as putative V(V)-reducing bacteria, while Methanosarcina spp. were identified as putative V(V)-reducing archaea. The bacteria may use the two nitrate reductases NarG and NapA for respiratory V(V) reduction, as has been demonstrated previously for other species. It is proposed that Methanosarcina spp. may reduce V(V) via anaerobic methane oxidation pathways (AOM-V) rather than via respiratory V(V) reduction performed by their bacterial counterparts, as indicated by the presence of genes associated with anaerobic methane oxidation coupled with metal reduction in the metagenome assembled genome (MAG) of Methanosarcina. Briefly, methane may be oxidized through the "reverse methanogenesis" pathway to produce electrons, which may be further captured by V(V) to promote V(V) reduction. More specially, V(V) reduction by members of Methanosarcina may be driven by electron transport (CoMS-SCoB heterodisulfide reductase (HdrDE), F420H2 dehydrogenases (Fpo), and multi-heme c-type cytochrome (MHC)). The identification of putative V(V)-reducing bacteria and archaea and the prediction of their different pathways for V(V) reduction expand current knowledge regarding the potential fate of V(V) in contaminated sites.

In-situ alkaline enhanced two-stage anaerobic digestion system for waste cooking oil and sewage sludge co-digestion.

Anaerobic digestion is a promising way for resource recovery from waste cooking oil (WCO) due to its high bio-methanation potential. In-situ mild alkaline (pH 8) enhanced two-stage continuous stirred tank reactors (ALK-2-CSTRs) were implemented to explore its efficiency in co-digesting WCO and sewage sludge with stepwise increase of WCO in the co-substrates. Results demonstrate that the ALK-2-CSTRs effectively promoted methane yield from the co-substrates via promoting hydrolysis, long chain fatty acids (LCFAs) degradation and protecting methanogens from exposure to high concentration of LCFAs directly. The maximum methane yield of the ALK-2-CSTRs is 39.2% higher than that of a single stage CSTR system at the optimal feed mixture of 45:55 (WCO:SS [VS]). The thermophilic operation applied to the stage-1 of the ALK-2-CSTRs failed to improve the methane yield when the methanogenic performance was stable; while upon WCO overloaded, the elevated temperature mitigated the deterioration of methanogenesis by stimulating the bioconversion of the toxic LCFAs, especially the unsaturated oleic acid. Microbial community analysis reveals the ALK-2-CSTRs stimulated the growth of lipolytic bacteria and hydrogenotrophic methanogens, which suggests the hydrogenotrophic methanogenic pathway was promoted. Cost evaluation demonstrates the economical superiority of the ALK-2-CSTR over the prevailing strategies developed for enhancing methane yield from the co-substrates.

Interaction of perfluorooctanoic acid with extracellular polymeric substances - Role of protein.

Perfluorooctanoic acid (PFOA) is nonbiodegradable, and adsorption is the main pathway for its removal in wastewater treatment plants (WWTPs). This study compared the capability of three types of sludge on adsorbing PFOA and investigated the role of extracellular polymeric substances (EPS) in the adsorption process. Results show that enhanced biological phosphorus removal (EBPR) sludge had the highest adsorption capacity for PFOA. Studies on the interaction between EPS and PFOA reveal that proteins play a crucial role in binding PFOA to EPS/sludge. Specifically, the aromatic and amide groups on the structure of protein can attract the C-F chains and carboxylic head of PFOA via hydrophobic interaction and electrostatic attraction, respectively. EPS of EBPR sludge has the highest amount of protein and binding sites, thus exhibits the highest adsorption capability for PFOA. This study reveals the interaction mechanism between PFOA and sludge EPS and provides new insight into the function of EPS in perfluoroalkyl substances removal in WWTPs.

Challenges of THP-AD centrate treatment using partial nitritation-anammox (PN/A) - inhibition, biomass washout, low alkalinity, recalcitrant and more.

The centrate produced from a thermal hydrolysis pretreatment coupled anaerobic digestion (THP-AD) system is generally characterized by high concentrations of ammonium and recalcitrant organics. In this study, a cost-effective partial nitritation-anammox (PN/A) process was developed to evaluate the potential challenges in THP-AD centrate treatment. The results show ammonium oxidizing bacteria (AOB) and anammox bacteria were seriously inhibited by THP-AD centrate, while long-term acclimation together with aeration optimization can mitigate such inhibition. A nitrogen removal rate (NRR) of 0.55 kg N/m3/d was obtained and maintained with 60% THP-AD centrate as feed. However, 100% THP-AD centrate caused sludge wash-out from PN reactor due to excessive polymer and high solids in influent. The alkalinity deficit also reduced the AOB activity. Moreover, anammox activity and overall NRR also declined (to 0.37 kg N/m3/d). The organics transformation mainly occurred in PN reactor with very low removal efficiency due to their recalcitrant characteristics. The humic acid-like, fulvic acid-like substances and building blocks were revealed as the major organic compounds in THP-AD centrate (51.5-53.8% TOC), which likely contributed to the recalcitrant. Nitrosomonas and Candidatus Brocadia were the major AOB and anammox bacteria in the PN and anammox reactors respectively. With the increased THP-AD centrate proportion in the feed, the abundance of both population declined. Interestingly, Denitratisoma, being the major denitrifying bacteria in anammox reactor, had relatively stable abundance (7.0-7.9%) when THP-AD centrate was improved from 3 and 100%, suggesting the inhibition on anammox bacteria was not due to the overgrowth of denitrifying microorganism despite the high organics loading rate. Overall, this study provides a guide to develop the energy-saving PN/A process for THP-AD centrate treatment by pointing out potential challenges and mitigating strategies.

Biomass enhances the reduction of oxidized pellets with carbon monoxide.

In this study, the reduction mechanism of using CO to reduce biomass-oxidized pellets (BOP) and general-oxidized pellets (GOP) was deeply analyzed. The effect of biomass addition on the reduction of oxidized pellets and the change of reduction kinetics were studied. The addition of 2 wt% biomass into pellets increases pores of the oxidized pellets, promotes the rate of CO entering the pellets and the overflow of CO2, which results in faster reduction of the oxidized pellets. The reduction reactions of BOP and GOP were controlled by internal diffusion, mixing control and interface control sequentially. Also, addition of the biomass to the pellets decreases the activation energy required for their reduction, from 87.30 to 80.65 kJ·mol-1. The addition of biomass shortens the reduction time by 3% which can reduce the energy consumption. Therefore, the biomass together with CO enhances the reduction of oxidized pellets and has real environmental benefits.

Research Relating to Low Back Pain and Physical Activity Reported Over the Period of 2000-2020.

BACKGROUND: Low back pain (LBP) is a highly prevalent musculoskeletal disorder that contributes to the greatest degree of disability worldwide. It has become a very serious public health problem that has attracted considerable research interest. The number of publications associated with LBP and physical activity (PA) is gradually increasing. Nevertheless, few studies have utilised visualisation in analysing the general aspects of this field. Therefore, we aimed to provide a systematic overview of global scientific research related to low back pain and physical activity from 2000 to 2020. It has significant benefits in terms of providing researchers with the status and trends of research on low back pain and physical activity. METHODS: Publications on Science Citation Index-Expanded of Web of Science from 2000 to 2020 were searched, and publications relevant to LBP and PA were analysed using Citespace and SPSS. Analyses mainly included cooperation amongst authors, countries and institutions; co-occurrence analysis of keywords; and co-citation analysis of references, revealing productive researchers and contributing institutions tracking the status and trend of research fields. RESULTS: Results of linear regression analysis showed that the number of publications on LBP and PA studies increased significantly (p<0.001). The subject categories predominantly focused on orthopaedics (2579, 26.54%), rehabilitation (2544, 26.18%) and sport sciences (2015, 25.44%). The United States had the highest number of published papers (2700, 27.789%) and citations (86, 958). In terms of the number of publications, amongst the top 20 journals, Spine contributed the most, whilst the British Journal of Sports Medicine had the highest impact factor (IF2019, 12.022). The University of Sydney had the highest number of publications (330 publications). Maher published the most papers (123 papers) and had the highest H-index (41). Several citation articles and keywords (such as aerobic, obesity and fear-avoidance beliefs) can be used to provide frontier clues for research on LBP and PA. CONCLUSION: The results of our study may provide information, such as research trends and frontiers of research and collaborating partners, institutions and countries, on LBP and PA.