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Aghilinasrollahabadi K, Saffari Ghandehari S, Kjellerup BV, Nguyen C, Saavedra Y, Li G. Assessing the performance of polyphosphate accumulating organisms in a full-scale side-stream enhanced biological phosphorous removal. Water Environ Res 2024; 96:e10961. [PMID: 38212140 DOI: 10.1002/wer.10961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 11/21/2023] [Accepted: 11/24/2023] [Indexed: 01/13/2024]
Abstract
Phosphorous (P) removal in wastewater treatment is essential to prevent eutrophication in water bodies. Side-stream enhanced biological phosphorous removal (S2EBPR) is utilized to improve biological P removal by recirculating internal streams within a side-stream reactor to generate biodegradable carbon (C) for polyphosphate accumulating organisms (PAOs). In this study, a full-scale S2EBPR system in a water resource recovery facility (WRRF) was evaluated for 5 months. Batch experiments revealed a strong positive correlation (r = 0.91) between temperature and C consumption rate (3.56-8.18 mg-COD/g-VSS/h) in the system, with temperature ranging from 14°C to 18°C. The anaerobic P-release to COD-uptake ratio decreased from 0.93 to 0.25 mg-P/mg-COD as the temperature increased, suggesting competition between PAOs and other C-consumers, such as heterotrophic microorganisms, to uptake bioavailable C. Microbial community analysis did not show a strong relationship between abundance and activity of PAO in the tested WRRF. An assessment of the economic feasibility was performed to compare the costs and benefits of a full scale WRRF with and without implementation of the S2EBPR technology. The results showed the higher capital costs required for S2EBPR were estimated to be compensated after 5 and 11 years of operation, respectively, compared to chemical precipitation and conventional EBPR. The results from this study can assist in the decision-making process for upgrading a conventional EBPR or chemical P removal process to S2EBPR. PRACTITIONER POINTS: Implementation of S2EBPR presents adaptable configurations, exhibiting advantages over conventional setups in addressing prevalent challenges associated with phosphorous removal. A full-scale S2EBPR WRRF was monitored over 5 months, and activity tests were used to measure the kinetic parameters. The seasonal changes impact the kinetic parameters of PAOs in the S2EBPR process, with elevated temperatures raising the carbon demand. PAOs abundance showed no strong correlation with their activity in the full-scale S2EBPR process in the tested WRRF. Feasibility assessment shows that the benefits from S2EBPR operation can offset upgrading costs from conventional BPR or chemical precipitation.
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Affiliation(s)
| | | | - Birthe Veno Kjellerup
- Department of Civil and Environmental Engineering, University of Maryland, College Park, Maryland, USA
| | | | | | - Guangbin Li
- Department of Civil and Environmental Engineering, University of Maryland, College Park, Maryland, USA
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Liu J, Yang L, Kjellerup BV, Xu Z. Viable but nonculturable (VBNC) state, an underestimated and controversial microbial survival strategy. Trends Microbiol 2023; 31:1013-1023. [PMID: 37225640 DOI: 10.1016/j.tim.2023.04.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 04/22/2023] [Accepted: 04/24/2023] [Indexed: 05/26/2023]
Abstract
As a unique microbial response to adverse circumstances, the viable but nonculturable (VBNC) state is characterized by the loss of culturability of microbial cells on/in nutrient media that normally support their growth, while maintaining metabolic activity. These cells can resuscitate to a culturable state under suitable conditions. Given the intrinsic importance of the VBNC state and recent debates surrounding it, there is a need to redefine and standardize the term, and to address essential questions such as 'How to differentiate VBNC from other similar terms?' and 'How can VBNC cells be standardly and accurately determined?'. This opinion piece aims at contributing to an improved understanding of the VBNC state and promoting its proper handling as an underestimated and controversial microbial survival strategy.
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Affiliation(s)
- Junyan Liu
- College of Light Industry and Food Science, Guangdong Provincial Key Laboratory of Lingnan Specialty Food Science and Technology, Academy of Contemporary Agricultural Engineering Innovations, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China; Key Laboratory of Green Processing and Intelligent Manufacturing of Lingnan Specialty Food, Ministry of Agriculture, Guangzhou 510225, China
| | - Liang Yang
- School of Medicine, Southern University of Science and Technology, Shenzhen 518055, China
| | - Birthe Veno Kjellerup
- Department of Civil and Environmental Engineering, University of Maryland, College Park, MD 20742, USA
| | - Zhenbo Xu
- School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, Engineering Research Center of Starch and Vegetable Protein Processing Ministry of Education, South China University of Technology, Guangzhou 510640, China; Department of Laboratory Medicine, the Second Affiliated Hospital of Shantou University Medical College, Shantou, China.
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Hirsch LO, Dubrovin IA, Gandu B, Emanuel E, Kjellerup BV, Ugur GE, Schechter A, Cahan R. Anode amendment with kaolin and activated carbon increases electricity generation in a microbial fuel cell. Bioelectrochemistry 2023; 153:108486. [PMID: 37302334 DOI: 10.1016/j.bioelechem.2023.108486] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 05/30/2023] [Accepted: 05/31/2023] [Indexed: 06/13/2023]
Abstract
The bacterial anode is a key factor for microbial fuel cell (MFC) performance. This study examined the potential of kaolin (fine clay) to enhance bacteria and conductive particle attachment to the anode. The bio-electroactivity of MFCs based on a carbon-cloth anode modified by immobilization with kaolin, activated carbon, and Geobacter sulfurreducens (kaolin-AC), with only kaolin (kaolin), and a bare carbon-cloth (control) anodes were examined. When the MFCs were fed with wastewater, the MFCs based on the kaolin-AC, kaolin, and bare anodes produced a maximum voltage of 0.6 V, 0.4 V, and 0.25 V, respectively. The maximum power density obtained by the MFC based on the kaolin-AC anode was 1112 mW‧m-2 at a current density of 3.33 A‧m-2, 12% and 56% higher than the kaolin and the bare anodes, respectively. The highest Coulombic efficiency was obtained by the kaolin-AC anode (16%). The relative microbial diversity showed that Geobacter displayed the highest relative distribution of 64% in the biofilm of the kaolin-AC anode. This result proved the advantage of preserving the bacterial anode exoelectrogens using kaolin. To our knowledge, this is the first study evaluating kaolin as a natural adhesive for immobilizing exoelectrogenic bacteria to anode material in MFCs.
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Affiliation(s)
- Lea Ouaknin Hirsch
- Department of Chemical Engineering, Ariel University, Ariel 40700, Israel
| | | | - Bharath Gandu
- Department of Chemical Engineering, Ariel University, Ariel 40700, Israel; Department of Environmental Studies, University of Delhi, New Delhi 110007, India
| | - Efrat Emanuel
- Department of Chemical Engineering, Ariel University, Ariel 40700, Israel
| | - Birthe Veno Kjellerup
- Department of Civil and Environmental Engineering, University of Maryland, 1147 Glenn L Martin Hall, College Park, MD 20742, USA
| | - Gizem Elif Ugur
- Imaging and Chemical Analysis Laboratory, Montana State University, Montana 59715, USA
| | - Alex Schechter
- Department of Chemical Sciences, Ariel University, Ariel 40700, Israel
| | - Rivka Cahan
- Department of Chemical Engineering, Ariel University, Ariel 40700, Israel.
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Vélez Justiniano YA, Goeres DM, Sandvik EL, Kjellerup BV, Sysoeva TA, Harris JS, Warnat S, McGlennen M, Foreman CM, Yang J, Li W, Cassilly CD, Lott K, HerrNeckar LE. Mitigation and use of biofilms in space for the benefit of human space exploration. Biofilm 2023; 5:100102. [PMID: 36660363 PMCID: PMC9843197 DOI: 10.1016/j.bioflm.2022.100102] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/21/2022] [Accepted: 12/22/2022] [Indexed: 01/08/2023] Open
Abstract
Biofilms are self-organized communities of microorganisms that are encased in an extracellular polymeric matrix and often found attached to surfaces. Biofilms are widely present on Earth, often found in diverse and sometimes extreme environments. These microbial communities have been described as recalcitrant or protective when facing adversity and environmental exposures. On the International Space Station, biofilms were found in human-inhabited environments on a multitude of hardware surfaces. Moreover, studies have identified phenotypic and genetic changes in the microorganisms under microgravity conditions including changes in microbe surface colonization and pathogenicity traits. Lack of consistent research in microgravity-grown biofilms can lead to deficient understanding of altered microbial behavior in space. This could subsequently create problems in engineered systems or negatively impact human health on crewed spaceflights. It is especially relevant to long-term and remote space missions that will lack resupply and service. Conversely, biofilms are also known to benefit plant growth and are essential for human health (i.e., gut microbiome). Eventually, biofilms may be used to supply metabolic pathways that produce organic and inorganic components useful to sustaining life on celestial bodies beyond Earth. This article will explore what is currently known about biofilms in space and will identify gaps in the aerospace industry's knowledge that should be filled in order to mitigate or to leverage biofilms to the advantage of spaceflight.
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Affiliation(s)
- Yo-Ann Vélez Justiniano
- ECLSS Development Branch, NASA Marshall Space Flight Center, Huntsville, AL, USA,Corresponding author.
| | - Darla M. Goeres
- The Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA,Chemical and Biological Engineering, Montana State University, Bozeman, MT, USA
| | | | - Birthe Veno Kjellerup
- Department of Civil and Environmental Engineering, University of Maryland, College Park, MD, USA
| | - Tatyana A. Sysoeva
- Department of Biological Sciences, The University of Alabama in Huntsville, Huntsville, AL, USA
| | - Jacob S. Harris
- Biomedical and Environmental Science Division, NASA Johnson Space Center, Houston, TX, USA
| | - Stephan Warnat
- The Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA,Mechanical Engineering, Montana State University, Bozeman, MT, USA
| | - Matthew McGlennen
- The Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA,Mechanical Engineering, Montana State University, Bozeman, MT, USA
| | - Christine M. Foreman
- The Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA,Chemical and Biological Engineering, Montana State University, Bozeman, MT, USA
| | - Jiseon Yang
- Biodesign Center for Fundamental and Applied Microbiomics, Arizona State University, Tempe, AZ, USA
| | - Wenyan Li
- Laboratory Support Services and Operations (LASSO), NASA Kennedy Space Center, Cape Canaveral, FL, USA
| | | | - Katelynn Lott
- Department of Biological Sciences, The University of Alabama in Huntsville, Huntsville, AL, USA
| | - Lauren E. HerrNeckar
- ECLSS Development Branch, NASA Marshall Space Flight Center, Huntsville, AL, USA
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Kjellerup BV, Nijenhuis I, Rossetti S. Editorial: Thematic issue on anaerobic biological dehalogenation. FEMS Microbiol Ecol 2022; 98:6780077. [PMID: 36308759 DOI: 10.1093/femsec/fiac108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 07/13/2022] [Accepted: 09/09/2022] [Indexed: 01/21/2023] Open
Affiliation(s)
- Birthe Veno Kjellerup
- A. James Clark School of Engineering, University of Maryland at College Park, 1147 Glenn L. Martin Hall, College Park, MD 20742, United States
| | - Ivonne Nijenhuis
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Simona Rossetti
- Water Research Institute (IRSA), National Research Council (CNR), via Salaria km 29300, 00015 Monterotondo (RM), Italy
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Natoli RM, Marinos DP, Montalvo RN, Degani Y, Ochenjele G, Griffith C, Ding A, Gitajn IL, Manson TT, Johnson AJ, Kjellerup BV, Harro JM, Joshi M, O'Toole RV. Poor Agreement Between Next-Generation DNA Sequencing and Bacterial Cultures in Orthopaedic Trauma Procedures. J Bone Joint Surg Am 2022; 104:497-503. [PMID: 35041629 DOI: 10.2106/jbjs.21.00785] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND Next-generation DNA sequencing (NGS) detects bacteria-specific DNA corresponding to the 16S ribosomal RNA gene and can identify bacterial presence with greater accuracy than traditional culture methods. The clinical relevance of these findings is unknown. The purpose of the present study was to compare the results from bacterial culture and NGS in order to characterize the potential use of NGS in orthopaedic trauma patients. METHODS A prospective cohort study was performed at a single academic, level-I trauma center. Three patient groups were enrolled: (1) patients undergoing surgical treatment of acute closed fractures (presumed to have no bacteria), (2) patients undergoing implant removal at the site of a healed fracture without infection, and (3) patients undergoing a first procedure for the treatment of a fracture nonunion who might or might not have subclinical infection. Surgical site tissue was sent for culture and NGS. The proportions of culture and NGS positivity were compared among the groups. The agreement between culture and NGS results was assessed with use of the Cohen kappa statistic. RESULTS Bacterial cultures were positive in 9 of 111 surgical sites (110 patients), whereas NGS was positive in 27 of 111 surgical sites (110 patients). Significantly more cases were positive on NGS as compared with culture (24% vs. 8.1%; p = 0.001), primarily in the acute closed fracture group. No difference was found in terms of the percent positivity of NGS when comparing the acute closed fracture, implant removal, and nonunion groups. With respect to bacterial identification, culture and NGS agreed in 73% of cases (κ = 0.051; 95% confidence interval, -0.12 to 0.22) indicating only slight agreement compared with expected chance agreement of 50%. CONCLUSIONS NGS identified bacterial presence more frequently than culture, but with only slight agreement between culture and NGS. It is possible that the increased frequency of bacterial detection with molecular methods is reflective of biofilm presence on metal or colonization with nonpathogenic bacteria, as culture methods have selection pressure posed by restrictive, artificial growth conditions and there are low metabolic activity and replication rates of bacteria in biofilms. Our data suggest that NGS should not currently substitute for or complement conventional culture in orthopaedic trauma cases with low suspicion of infection. LEVEL OF EVIDENCE Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.
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Affiliation(s)
- Roman M Natoli
- Department of Orthopaedics, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Dimitrius P Marinos
- Department of Orthopaedics, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Ryan N Montalvo
- Department of Orthopaedics, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Yasmin Degani
- Department of Orthopaedics, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - George Ochenjele
- Department of Orthopaedics, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Cullen Griffith
- Department of Orthopaedics, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Anthony Ding
- Department of Orthopaedics, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - I Leah Gitajn
- Department of Orthopaedics, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Theodore T Manson
- Department of Orthopaedics, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Aaron J Johnson
- Department of Orthopaedics, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Birthe Veno Kjellerup
- Department of Civil and Environmental Engineering, University of Maryland, College Park, Maryland
| | - Janette M Harro
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, Maryland
| | - Manjari Joshi
- Division of Infectious Diseases, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Robert V O'Toole
- Department of Orthopaedics, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, Maryland
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Ronin D, Boyer J, Alban N, Natoli RM, Johnson A, Kjellerup BV. Current and novel diagnostics for orthopedic implant biofilm infections: a review. APMIS 2021; 130:59-81. [PMID: 34862649 DOI: 10.1111/apm.13197] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 11/25/2021] [Indexed: 12/12/2022]
Abstract
Biofilm infections involving orthopedic implants are a global problem. They contribute to severe complications and mortality, as well as increased use of antibiotic treatments and development of antibiotic-resistant microorganisms. More than 1 million hip and knee arthroplasties are performed each year in the United States. These hard-to-treat infections lead to patient distress, increased morbidity, and high financial costs to both patients and healthcare systems. There is a need to improve the diagnosis of such biofilm infections to allow for earlier detection and treatment. Current diagnostics rely on clinical signs for infections such as loss of function, fever, rubor, patient history of the predisposing condition, persisting infection, failure of antibiotic treatment, and documentation of antibiotic failure. Below, we present a framework which outlines the data gaps in the conventional laboratory techniques used in clinical diagnostics; we also discuss promising novel diagnostic methods which are currently used solely in research. It is critical to assess these novel infection diagnostic techniques and address the data gaps and clinical hesitance preventing application in a clinical setting. Additionally, the combination of conventional and novel diagnostic technologies would streamline the diagnostic process of biofilm infections associated with orthopedic implants.
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Affiliation(s)
- Dana Ronin
- Department of Civil and Environmental Engineering, University of Maryland, College Park, Maryland, USA.,Fischell Department of Bioengineering, University of Maryland, College Park, Maryland, USA
| | - Jessica Boyer
- Department of Civil and Environmental Engineering, University of Maryland, College Park, Maryland, USA.,Fischell Department of Bioengineering, University of Maryland, College Park, Maryland, USA
| | - Nathan Alban
- Department of Civil and Environmental Engineering, University of Maryland, College Park, Maryland, USA.,Fischell Department of Bioengineering, University of Maryland, College Park, Maryland, USA
| | - Roman M Natoli
- Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Aaron Johnson
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Birthe Veno Kjellerup
- Department of Civil and Environmental Engineering, University of Maryland, College Park, Maryland, USA.,Fischell Department of Bioengineering, University of Maryland, College Park, Maryland, USA
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Xu Z, Liu Z, Soteyome T, Hua J, Zhang L, Yuan L, Ye Y, Cai Z, Yang L, Chen L, Harro JM, Kjellerup BV, Liu J, Li Y. Impact of pmrA on Cronobacter sakazakii planktonic and biofilm cells: A comprehensive transcriptomic study. Food Microbiol 2021; 98:103785. [PMID: 33875213 DOI: 10.1016/j.fm.2021.103785] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 12/30/2020] [Accepted: 03/05/2021] [Indexed: 10/21/2022]
Abstract
Cronobacter sakazakii is an emerging opportunistic foodborne pathogen causing rare but severe infections in neonates. Furthermore, the formation of biofilm allows C. sakazakii to persist in different environments. We have demonstrated that the mutator phenotype ascribed to deficiency of the pmrA gene results in more biomass in the first 24 h but less during the post maturation stage (7-14 d) compared with BAA 894. The present study aimed to investigate the regulatory mechanism modulating biofilm formation due to pmrA mutation. The transcriptomic analyses of BAA 894 and s-3 were performed by RNA-sequencing on planktonic and biofilm cells collected at different time points. According to the results, when comparing biofilm to planktonic cells, expression of genes encoding outer membrane proteins, lysozyme, etc. were up-regulated, with LysR family transcriptional regulators, periplasmic proteins, etc. down-regulated. During biofilm formation, cellulose synthase operon genes, flagella-related genes, etc. played essential roles in different stages. Remarkably, pmrA varies the expression of a number of genes related to motility, biofilm formation, and antimicrobial resistance, including srfB, virK, mviM encoding virulence factor, flgF, fliN, etc. encoding flagellar assembly, and marA, ramA, etc. encoding AraC family transcriptional regulators in C. sakazakii. This study provides valuable insights into transcriptional regulation of C. sakazakii pmrA mutant during biofilm formation.
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Affiliation(s)
- Zhenbo Xu
- School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou, 510640, China; Department of Clinical Pharmacy and Translational Science, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN, 38103, USA; Home Economics Technology, Rajamangala University of Technology Phra Nakhon, Bangkok, Thailand; National Institute of Fundamental Studies, Hantana Road, Kandy, Sri Lanka; Overseas Expertise Introduction Center for Discipline Innovation of Food Nutrition and Human Health (111 Center), Guangzhou, 510640, China
| | - Ziqi Liu
- School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou, 510640, China
| | - Thanapop Soteyome
- National Institute of Fundamental Studies, Hantana Road, Kandy, Sri Lanka
| | - Jingjing Hua
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China
| | - Liang Zhang
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
| | - Lei Yuan
- College of Food Science and Engineering, Yangzhou University, Yangzhou, China
| | - Yanrui Ye
- School of Biological Science and Engineering, South China University of Technology, Guangzhou, 510640, China
| | - Zhao Cai
- School of Medicine, Southern University of Science and Technology, Shenzhen, 518055, Guangdong, China
| | - Liang Yang
- School of Medicine, Southern University of Science and Technology, Shenzhen, 518055, Guangdong, China
| | - Ling Chen
- School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou, 510640, China
| | - Janette M Harro
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD, 21201, USA
| | - Birthe Veno Kjellerup
- Department of Civil and Environmental Engineering, University of Maryland, College Park, MD, 20742, USA
| | - Junyan Liu
- Department of Civil and Environmental Engineering, University of Maryland, College Park, MD, 20742, USA
| | - Yanyan Li
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, 18 Shilongshan Road, Xihu District, Hangzhou, 310024, Zhejiang Province, China.
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Yan Z, Huang M, Melander C, Kjellerup BV. Dispersal and inhibition of biofilms associated with infections. J Appl Microbiol 2019; 128:1279-1288. [PMID: 31618796 DOI: 10.1111/jam.14491] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 09/30/2019] [Accepted: 10/11/2019] [Indexed: 12/26/2022]
Abstract
As bacteria aggregate and form biofilms on surfaces in the human body such as tissues, indwelling medical devices, dressings and implants, they can cause a significant health risk. Bacterial biofilms possess altered phenotypes: physical features that facilitate antibiotic resistance and evasion of the host immune response. Since metabolic and physical factors contribute to biofilm maturation and persistence, an objective in antibiofilm therapy is to target these factors to deliver innovative approaches for solving these important health problems. Currently, there is little research on the direct immunological effects resulting from the introduction of foreign components to the body pertaining to biofilm inhibition methods. Detailed research involving animal models is necessary to better understand the biological side effects of synthetic peptides, genetically modified bacteriophages and isolated proteins and any resistance that may develop from these approaches.
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Affiliation(s)
- Z Yan
- Department of Civil and Environmental Engineering, University of Maryland at College Park, College Park, MD, USA
| | - M Huang
- Department of Civil and Environmental Engineering, University of Maryland at College Park, College Park, MD, USA
| | - C Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, USA
| | - B V Kjellerup
- Department of Civil and Environmental Engineering, University of Maryland at College Park, College Park, MD, USA
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10
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Saba B, Khan M, Christy AD, Kjellerup BV. Microbial phyto-power systems – A sustainable integration of phytoremediation and microbial fuel cells. Bioelectrochemistry 2019; 127:1-11. [DOI: 10.1016/j.bioelechem.2018.12.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 12/14/2018] [Accepted: 12/14/2018] [Indexed: 10/27/2022]
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11
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Capozzi SL, Jing R, Rodenburg LA, Kjellerup BV. Positive Matrix Factorization analysis shows dechlorination of polychlorinated biphenyls during domestic wastewater collection and treatment. Chemosphere 2019; 216:289-296. [PMID: 30384297 DOI: 10.1016/j.chemosphere.2018.10.151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 10/11/2018] [Accepted: 10/21/2018] [Indexed: 06/08/2023]
Abstract
Polychlorinated biphenyls (PCBs) are persistent, toxic and bioaccumulative pollutants. One of the few pathways via which they break down is microbial dechlorination, which has been shown to occur in sewers. Questions remain about where within sewers this process takes place and which conditions encourage dechlorination. These issues were examined using a large data set on PCBs in influent and effluents from a main and bypass outfall from a wastewater treatment facility in the Mid-Atlantic region of the USA. A data set containing 64 chromatographic peaks representing 103 PCB congeners measured in 74 whole water samples was analyzed by Positive Matrix Factorization (PMF). PMF resolved four factors, three of which represented Aroclors 1242, 1254, and 1260. The remaining factor represented an advanced dechlorination regime of PCBs characterized by high proportions of PCBs 4 and 19 and comprised about 35% of the PCBs in the treated effluent, among the highest levels of dechlorination observed in previous studies. Concentrations of dechlorination products were not correlated with total suspended solids, indicating they were mostly dissolved and explaining the poor removal via sedimentation during the treatment process. The factors representing Aroclors were positively correlated with total influent flow, but the dechlorination signal was not, suggesting that the dechlorination signal arises from different locations and/or processes than the Aroclors. Even though treatment and dechlorination reduced the dioxin-like toxicity of the PCB mixture, this effect might be offset by the incomplete removal of dechlorination products.
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Affiliation(s)
- Staci L Capozzi
- Department of Civil and Environmental Engineering, University of Maryland, College Park, MD, United States; Geosyntec Consultants, Columbia, MD 21046, United States
| | - Ran Jing
- Department of Civil and Environmental Engineering, University of Maryland, College Park, MD, United States
| | - Lisa A Rodenburg
- Department of Environmental Sciences, Rutgers University, New Brunswick, NJ, United States
| | - Birthe Veno Kjellerup
- Department of Civil and Environmental Engineering, University of Maryland, College Park, MD, United States.
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Capozzi SL, Bodenreider C, Prieto A, Payne RB, Sowers KR, Kjellerup BV. Colonization and growth of dehalorespiring biofilms on carbonaceous sorptive amendments. Biofouling 2019; 35:50-58. [PMID: 30786761 DOI: 10.1080/08927014.2018.1563892] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 12/19/2018] [Indexed: 06/09/2023]
Abstract
Removal of polychlorinated biphenyls (PCBs) from contaminated sediments is a priority due to accumulation in the food chain. Recent success with reduction of PCB bioavailability due to adsorption onto activated carbon led to the recognition of in situ treatment as a remediation approach. In this study, reduced bioavailability and subsequent break-down of PCBs in dehalorespiring biofilms was investigated using Dehalobium chlorocoercia DF1. DF1 formed a patchy biofilm ranging in thickness from 3.9 to 6.7 µm (average 4.6 ± 0.87 µm), while the biofilm coverage varied from 5.5% (sand) to 20.2% (activated carbon), indicating a preference for sorptive materials. Quantification of DF1 biofilm bacteria showed 1.2-15.3 × 109 bacteria per gram of material. After 22 days, coal activated carbon, bone biochar, polyoxymethylene, and sand microcosms had dechlorinated 73%, 93%, 100%, and 83%, respectively. These results show that a biofilm-based inoculum for bioaugmentation of PCBs in sediment can be an efficient approach.
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Affiliation(s)
- Staci L Capozzi
- a Department of Civil and Environmental Engineering , University of Maryland , College Park , MD , USA
- b Geosyntec Consultants , Columbia , MD , USA
| | - Coline Bodenreider
- a Department of Civil and Environmental Engineering , University of Maryland , College Park , MD , USA
| | - Ana Prieto
- c Department of Civil Engineering , Universidad de Chile , Santiago , Chile
| | - Rayford B Payne
- d Department of Marine Biotechnology, Institute of Marine and Environmental Technology , University of Maryland Baltimore County , Baltimore , MD , USA
| | - Kevin R Sowers
- d Department of Marine Biotechnology, Institute of Marine and Environmental Technology , University of Maryland Baltimore County , Baltimore , MD , USA
| | - Birthe Veno Kjellerup
- a Department of Civil and Environmental Engineering , University of Maryland , College Park , MD , USA
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Akbari F, Kjellerup BV. Elimination of Bloodstream Infections Associated with Candida albicans Biofilm in Intravascular Catheters. Pathogens 2015; 4:457-69. [PMID: 26131615 PMCID: PMC4584267 DOI: 10.3390/pathogens4030457] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 06/07/2015] [Accepted: 06/19/2015] [Indexed: 11/16/2022] Open
Abstract
Intravascular catheters are among the most commonly inserted medical devices and they are known to cause a large number of catheter related bloodstream infections (BSIs). Biofilms are associated with many chronic infections due to the aggregation of microorganisms. One of these organisms is the fungus Candida albicans. It has shown to be one of the leading causes of catheter-related BSIs. The presence of biofilm on intravascular catheters provide increased tolerance against antimicrobial treatments, thus alternative treatment strategies are sought. Traditionally, many strategies, such as application of combined antimicrobials, addition of antifungals, and removal of catheters, have been practiced, but they were not successful in eradicating BSIs. Since these fungal infections can result in significant morbidity, mortality, and increased healthcare cost, other promising preventive strategies, including antimicrobial lock therapy, chelating agents, alcohol, and biofilm disruptors, have been applied. In this review, current success and failure of these new approaches, and a comparison with the previous strategies are discussed in order to understand which preventative treatment is the most effective in controlling the catheter-related BSIs.
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Affiliation(s)
- Freshta Akbari
- Department of Biological Sciences, Goucher College, Baltimore, MD 21204, USA.
| | - Birthe Veno Kjellerup
- Department of Civil and Environmental Engineering, University of Maryland at College Park, College Park, MD 20742, USA.
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Kjellerup BV, Naff C, Edwards SJ, Ghosh U, Baker JE, Sowers KR. Effects of activated carbon on reductive dechlorination of PCBs by organohalide respiring bacteria indigenous to sediments. Water Res 2014; 52:1-10. [PMID: 24440760 DOI: 10.1016/j.watres.2013.12.030] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 12/11/2013] [Accepted: 12/23/2013] [Indexed: 06/03/2023]
Abstract
Polychlorinated biphenyls (PCBs) have accumulated in aquatic sediments due to their inherent chemical stability and their presence poses a risk due to their potential toxicity in humans and animals. Granular activated carbon (GAC) has been applied to PCB contaminated sediment sites to reduce the aqueous concentration by sequestration thus reducing the PCB exposure and toxicity to both benthic and aquatic organisms. However, it is not known how the reduction of PCB bioavailability by adsorption to GAC affects bacterial transformation of PCBs by indigenous organohalide respiring bacteria. In this study, the impact of GAC on anaerobic dechlorination by putative organohalide respiring bacteria indigenous to sediment from Baltimore Harbor was examined. It was shown that the average Cl/biphenyl after dehalogenation of Aroclor 1260 was similar between treatments with and without GAC amendment. However, GAC caused a substantial shift in the congener distribution whereby a smaller fraction of highly chlorinated congeners was more extensively dechlorinated to mono- through tri-chlorinated congeners compared to the formation of tri- through penta-chlorinated congeners in unamended sediment. The results combined with comparative sequence analysis of 16S rRNA gene sequences suggest that GAC caused a community shift to putative organohalide respiring phylotypes that coincided with more extensive dechlorination of ortho and unflanked chlorines. This shift in activity by GAC shown here for the first time has the potential to promote greater degradation in situ by promoting accumulation of less chlorinated congeners that are generally more susceptible to complete mineralization by aerobic PCB degrading bacteria.
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Affiliation(s)
- B V Kjellerup
- Goucher College, Department of Biological Sciences, 1021 Dulaney Valley Road, Baltimore, MD 21204, USA.
| | - C Naff
- Institute of Marine and Environmental Technology, Columbus Center, University of Maryland, 701 E. Pratt Street, Baltimore, MD 21202, USA
| | - S J Edwards
- Goucher College, Department of Biological Sciences, 1021 Dulaney Valley Road, Baltimore, MD 21204, USA
| | - U Ghosh
- University of Maryland Baltimore County, Department of Civil and Environmental Engineering, 1000 Hilltop Circle, Baltimore, MD 21250, USA
| | - J E Baker
- Center for Urban Waters, University of Washington-Tacoma, 326 East D Street, Tacoma, WA 98421, USA
| | - K R Sowers
- Institute of Marine and Environmental Technology, Columbus Center, University of Maryland, 701 E. Pratt Street, Baltimore, MD 21202, USA
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Kjellerup BV, Kjeldsen KU, Lopes F, Abildgaard L, Ingvorsen K, Frølund B, Sowers KR, Nielsen PH. Biocorrosion and biofilm formation in a nutrient limited heating system subjected to alternating microaerophilic conditions. Biofouling 2009; 25:727-737. [PMID: 20183131 DOI: 10.1080/08927010903114611] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Severe biofilm formation and biocorrosion have been observed in heating systems even when the water quality complied with existing standards. The coupling between water chemistry, biofilm formation, species composition, and biocorrosion in a heating system was investigated by adding low concentrations of nutrients and oxygen under continuous and alternating dosing regimes. Molecular analysis of 16S rRNA gene fragments demonstrated that the amendments did not cause changes in the overall bacterial community composition. The combined alternating dosing of nutrients and oxygen caused increased rates of pitting (bio-) corrosion. Detection of bacteria involved in sulfide production and oxidation by retrieval of the functional dsrAB and apsA genes revealed the presence of Gram-positive sulfate- and sulfite-reducers and an unknown sulfur-oxidizer. Therefore, to control biocorrosion, sources of oxygen and nutrients must be limited, since the effect of the alternating operational conditions apparently is more important than the presence of potentially corrosive biofilm bacteria.
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Affiliation(s)
- B V Kjellerup
- Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Denmark.
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Kjellerup BV, Olesen BH, Nielsen JL, Sowers KR, Nielsen PH. In situ detection of bacteria involved in cathodic depolarization and stainless steel surface corrosion using microautoradiography. J Appl Microbiol 2008; 105:2231-8. [PMID: 19016973 DOI: 10.1111/j.1365-2672.2008.03944.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AIMS To examine the activity of bacteria involved in cathodic depolarization and surface corrosion on stainless steel in an in situ model system. METHODS AND RESULTS The microautoradiographic technique (MAR) was used to evaluate the activity of bacterial populations on stainless steel surfaces with a single cell resolution. Anaerobic uptake and fixation of (14)C-labelled bicarbonate occurred within corrosion sites in the absence of atmospheric hydrogen or other external electron donors, whereas it was taken up and fixed by bacteria at all other stainless steel surfaces in the presence of atmospheric hydrogen. This indicates that the bacteria utilized electrons originating from the corrosion sites due to the ongoing corrosion (cathodic depolarization). CONCLUSION Under in situ conditions, bacteria were fixating (14)C-labelled bicarbonate at corrosion sites in the absence of atmospheric hydrogen. This indicates that electrons transferred to the bacteria provided energy for bicarbonate fixation due to cathodic depolarization. SIGNIFICANCE AND IMPACT OF THE STUDY Application of the MAR method showed ongoing biocorrosion in the applied in situ model system and allowed in situ examination of bacterial activity on a single cell level directly on a metal surface providing information about potential corrosion mechanisms. Furthermore, application of fluorescence in situ hybridization in combination with MAR allows for identification of the active bacteria.
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Affiliation(s)
- B V Kjellerup
- University of Maryland Biotechnology Institute, Center of Marine Biotechnology, Baltimore, MD, USA
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Kjellerup BV, Gudmonsson G, Sowers K, Nielsen PH. Evaluation of analytical methods for determining the distribution of biofilm and active bacteria in a commercial heating system. Biofouling 2006; 22:145-51. [PMID: 17290859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Danish district heating systems have good water quality, but continue to suffer from biofouling and biocorrosion. Localisation analyses of bacteria using microautoradiography were performed for one system in order to obtain detailed information for solving these problems. A mass balance showed that 77% of the bacteria were located at surfaces, with 23% in the bulk water, and 9% of the total carbon originated from biomass, while 91% was dissolved in the bulk water. The presence of active bacteria was determined with microautoradiography which showed that biofilms contained 99% and 1% were in the bulk water. A high bacterial functional diversity was observed, with active mesophilic and thermophilic bacteria under aerobic and anaerobic conditions and with potentially corrosive biofilm bacteria present. The study reveals that by applying the activity based approach, the ratio of living and dead bacteria in the biofilm and bulk water in this type of system could be accurately determined. Also, the results emphasise that to minimise biofilm growth and biocorrosion, monitoring should be established focusing on the surfaces, since bulk water parameters do not reflect bacterial activity.
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Affiliation(s)
- B V Kjellerup
- Danish Technological Institute, Center for Chemistry and Water, Aalborg University, Aalborg, Denmark.
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Kjellerup BV, Veeh RH, Sumithraratne P, Thomsen TR, Buckingham-Meyer K, Frølund B, Sturman P. Monitoring of microbial souring in chemically treated, produced-water biofilm systems using molecular techniques. J Ind Microbiol Biotechnol 2005; 32:163-70. [PMID: 15843975 DOI: 10.1007/s10295-005-0222-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2004] [Accepted: 03/18/2005] [Indexed: 10/25/2022]
Abstract
The identification of bacteria in oil production facilities has previously been based on culture techniques. However, cultivation of bacteria from these often-extreme environments can lead to errors in identifying the microbial community members. In this study, molecular techniques including fluorescence in situ hybridization, PCR, denaturing gradient gel electrophoresis, and sequencing were used to track changes in bacterial biofilm populations treated with nitrate, nitrite, or nitrate+molybdate as agents for the control of sulfide production. Results indicated that nitrite and nitrate+molybdate reduced sulfide production, while nitrate alone had no effect on sulfide generation. No long-term effect on sulfide production was observed. Initial sulfate-reducing bacterial numbers were not influenced by the chemical treatments, although a significant increase in sulfate-reducing bacteria was observed after termination of the treatments. Molecular analysis showed a diverse bacterial population, but no major shifts in the population due to treatment effects were observed.
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Affiliation(s)
- B V Kjellerup
- The Danish Technological Institute, Teknologiparken, Kongsvangs Alle 29, Aarhus, 8000, Denmark
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Abstract
Culture-independent investigations of the bacterial diversity and activity in district heating systems with and without corrosion did not make it possible to relate one group of microorganisms with the observed corrosion. Fluorescence in situ hybridization by oligonucleotide probes revealed the dominance of beta-proteobacteria, sulphate reducing prokaryotes and alpha-proteobacteria. Analysis of a clone library from one Danish heating (DH) system showed that the most sequences formed two clusters within the alpha-proteobacteria affiliated to the families Rhizobiaceae and Acetobacteraceae and two clusters within the beta-proteobacteria belonging to the family Comamonadaceae. Functional groups were determined by microautoradiography showing aerobic and anaerobic bacteria (sulphate reducing and methanogenic bacteria). The corrosion study showed that pitting corrosion rates were five to ten times higher than the general corrosion rates, suggesting the presence of biocorrosion. The results indicate that several bacterial groups could be involved in corrosion of DH system piping including sulphate reducing prokaryotes, Acidovorax (within the beta-proteobacteria), methanogenic bacteria and others.
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Affiliation(s)
- B V Kjellerup
- Danish Technological Institute, Centre for Chemistry and Water Technology, Arhus C., Denmark
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Olesen BH, Lorenzen J, Kjellerup BV, Odum S, Nielsen PH, Frølund B. MIC mitigation in a 100 MW district heating peak load unit. Water Sci Technol 2004; 49:99-105. [PMID: 14982169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
During inspection of AISI316 stainless steel plate heat exchangers in a district heating peak load unit, localised corrosion attacks along with indications of microbiological activity were found on the boiler side beneath patches of sturdy black deposits. Bacteria and sulphide were detected within black deposits. Thorough investigation of the boiler system revealed several incidents of localised corrosion on low alloy steel along with deposits of organic matter and bacteria primarily in places with stagnant water or places operating at a low flow rate. A relatively large amount of bacteria was detected within the system, primarily in deposits and around corrosion sites. The observations suggested the combination of deposits and bacterial activity, being the major reason for the observed corrosion. Prior to the investigation, the boiler system had operated with cat-/anion-exchanged, de-aerated water for 3 years, during which the water fulfilled strict chemical limits set to minimise corrosion. Based on these findings, the system has been modified in order to minimise the risk of microbiologically influenced corrosion and a monitoring program for fouling and corrosion has been established.
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Affiliation(s)
- B H Olesen
- Department of Environmental and Water Technology, Danish Technological Institute, Teknologiparken, DK-8000 Arhus, Denmark.
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Kjellerup BV, Olesen BH, Nielsen JL, Frølund B, Odum S, Nielsen PH. Monitoring and characterisation of bacteria in corroding district heating systems using fluorescence in situ hybridisation and microautoradiography. Water Sci Technol 2003; 47:117-122. [PMID: 12701915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Presence of biofilm and biocorrosion has been observed in Danish district heating (DH) systems despite very good water quality that was expected to prevent significant microbial growth. The microbiological water quality was investigated in order to identify the dominating bacterial groups on surfaces with corrosion problems. Water samples from 29 DH systems were investigated for the total number of bacteria and presence of sulphate reducing bacteria (SRBs). SRBs were found to be present in more than 80% of the DH systems. The microbial population in samples from 2 DH system (biofilm from a test coupon and an in situ sample from a heat exchanger) was investigated with fluorescence in situ hybridisation, and the results showed significant differences in population composition. Betaproteobacteria was the dominant population in both samples. SRBs were present in both samples but were most numerous in the biofilm from the test coupon. Examination of functional groups based on uptake of radiolabelled acetate (microautoradiography) showed presence of both aerobic and anaerobic bacteria despite the fact that oxygen is not anticipated in DH systems.
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Affiliation(s)
- B V Kjellerup
- Department of Environment, Danish Technological Institute, Teknologiparken, DK-8000 Arhus C, Denmark
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Kjellerup BV, Keiding K, Nielsen PH. Monitoring and troubleshooting of non-filamentous settling and dewatering problems in an industrial activated sludge treatment plant. Water Sci Technol 2001; 44:155-162. [PMID: 11547978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A large industrial activated sludge wastewater treatment plant had temporary problems with settling and dewatering of the sludge. Microscopical investigations revealed that the poor settling properties were not due to presence of filamentous bacteria, but poor floc properties. In order to characterise the changes in floc properties that led to settling and dewatering problems and to find reasons for this taking place, a comprehensive monitoring program was conducted during more than one year. The monitoring program included various measurements of floc settleability, floc strength and sludge dewaterability. The monitoring program revealed that a deterioration of the floc strength and the settling properties in the process tanks was closely connected to downstream dewatering problems and poor effluent quality. Particularly severe problems were observed a few weeks after the production at the factory had started after summer closedown. Possible reasons for the changes in floc properties in the process tanks were found by a) analysing change in wastewater composition by evaluating the different production lines in the industrial plant, b) evaluating the operation of the plant, and c) performing short-term laboratory experiments testing factors that could potentially affect floc properties (absence of oxygen, presence of sulphide, detergents, etc). Among several measured parameters, the use of floc strength measurements in particular proved useful to monitor the activated sludge floc properties at this industrial plant. The described strategy can be useful in general to find and solve many solid/liquid separation problems in activated sludge wastewater treatment plants.
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Affiliation(s)
- B V Kjellerup
- Danish Technological Institute, Department of Environment, Arhus
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