Mechanical properties of biofilms in water distribution and bioremediation systems
| dc.contributor.author | Hasan, Md Ibnul | |
| dc.date.accessioned | 2025-06-20T00:37:47Z | |
| dc.date.available | 2025-06-20T00:37:47Z | |
| dc.date.issued | 2025-05 | |
| dc.identifier.uri | http://hdl.handle.net/11122/15969 | |
| dc.description | Dissertation (Ph.D.) University of Alaska Fairbanks, 2025 | en_US |
| dc.description.abstract | This dissertation explores biofilm dynamics in water distribution and acid mine drainage (AMD) treatment, focusing on their roles in resource recovery and public health. Biofilms consist of microbial communities in a self-produced extracellular polymeric substance (EPS) matrix, which influences their mechanical and structural properties based on EPS composition, environmental conditions, and biofilm age. In drinking water distribution systems (DWDS), biofilms pose health hazards as they harbor pathogens and encourage metal corrosion. The composition of extracellular polymeric substances (EPS), particularly its high protein content, is noted in downstream areas, facilitating biofilm development in conditions of reduced chlorine and higher temperature turbidity. Traditional antimicrobial strategies often fail due to the protective EPS matrix, highlighting the need for targeted biofilm control strategies. On the other hand, biofilms show promise in AMD treatment, where biofilm-based bioreactors utilizing sulfate-reducing bacteria (SRB) effectively neutralize acidity and recover valuable metals, including rare earth elements. SRB bioreactors demonstrated sulfate reduction rates of up to 92.8% and near-complete removal of essential metals, showcasing the ability of biofilms to facilitate precipitation and biosorption under extreme conditions. The mechanical properties (as Young’s modulus) of biofilms were observed to vary with environmental conditions and biofilm age, influencing their resilience to mechanical stress. In DWDS, these properties impact biofilm control and removal efforts, while in AMD treatment, increased biofilm stiffness supports structural stability for effective metal removal. Advanced techniques like confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM) assessed biofilm characteristics, emphasizing the need for site-specific management strategies. Findings indicate that successful biofilm management necessitates an understanding of mechanics, EPS composition, and environmental factors. Future research should enhance biofilm control technologies and explore enzyme-based disruptors, balancing sustainability and public health concerns while optimizing resource recovery. | en_US |
| dc.description.sponsorship | National Science Foundation (grant #1752601), USGS NIWR | en_US |
| dc.description.tableofcontents | Chapter 1: General introduction -- 1.1 Background -- 1.2 Research objectives -- 1.3 Organizational overview -- 1.4 References. Chapter 2: Understanding biofilm mechanical properties: insights into environmental applications and challenges -- 2.1 Abstract -- 2.2 Background -- 2.2.1 Definition of biofilms -- 2.2.2 Importance of biofilm in different environmental/aquatic systems -- 2.2.3 Significance of studying biofilm mechanical properties -- 2.3 Perspectives of biofilms -- 2.3.1 Biological perspective -- 2.3.2 Chemical perspective -- 2.3.3 Materials perspective -- 2.3.4 Other perspectives -- 2.4 Methods of measuring biofilm mechanical properties -- 2.5 Factors influencing biofilm mechanical properties -- 2.5.1 Microbial community -- 2.5.2 EPS composition -- 2.5.3 Environmental conditions -- 2.5.4 Biofilm age -- 2.5.5 Bulk water chemistry -- 2.5.6 Antimicrobials and detachment-promoting agents -- 2.5.7 Surface properties -- 2.5.8 Quorum sensing -- 2.6 Mechanical properties of biofilms in different environmental systems -- 2.7 Role of mechanical properties in biofilm functions -- 2.8 Conclusions -- 2.9 References -- 2.10 Tables and figures. Chapter 3: Matrix matters: how extracellular substances shape biofilm structure and mechanical properties -- 3.1 Abstract -- 3.2 Background -- 3.3 Research plan and methodology -- 3.3.1 Biofilm growth conditions -- 3.3.2 EPS modifier experiements -- 3.3.3 Mechanical property determination -- 3.3.4 EPS composition analyses -- 3.3.5 Physical characteristics determination -- 3.3.6 Statistical analysis -- 3.4 Results -- 3.5 Discussion -- 3.6 Conclusions -- 3.7 Acknowledgments -- 3.8 References -- 3.9 Tables and figures -- Appendix A: Supplemental materials. Chapter 4: Investigating the properties of in-situ drinking water biofilms in a full-scale water distribution system -- 4.1 Abstract -- 4.2 Background -- 4.3 Methodology -- 4.4 Results and discussion -- 4.5 Conclusion -- 4.6 References -- 4.7 Tables and figures -- Appendix B: Supplemental materials. Chapter 5: Investigating the biofilm properties in sulfidogenic bioreactors removing rare earth elements from acid mine drainage -- 5.1 Abstract -- 5.2 Introduction -- 5.3 Methodology -- 5.3.1 Chemical reagents and nutrient supplements -- 5.3.2 Inoculum -- 5.3.3 Synthetic AMD -- 5.3.4 Sulfidogenic bioreactor -- 5.3.5 Analysis -- 5.3.6 Statistical analysis -- 5.4 Results and discussions -- 5.4.1 Sulfate removal -- 5.4.2 pH -- 5.4.3 Removal/removal of Metals/REE -- 5.4.4 Biofilm characteristics -- 5.4.5 Microbial community composition of bioreactor biofilms -- 5.5 Conclusions -- 5.6 References -- 5.7 Tables and figures -- Appendix C: Supplementary information. Chapter 6: General conclusions -- 6.1 Conclusions -- 6.2 Limitations -- 6.3 Recommendations for future work. | en_US |
| dc.language.iso | en_US | en_US |
| dc.subject | Biofilms | en_US |
| dc.subject | Mechanical properties of biofilms | en_US |
| dc.subject | Development of biofilms | en_US |
| dc.subject | Control of biofilms | en_US |
| dc.subject | Industrial applications of biofilms | en_US |
| dc.subject | Acid mine drainage | en_US |
| dc.subject.other | Doctor of Philosophy in Engineering | en_US |
| dc.title | Mechanical properties of biofilms in water distribution and bioremediation systems | en_US |
| dc.type | Dissertation | en_US |
| dc.type.degree | phd | en_US |
| dc.identifier.department | Department of Civil, Geological, and Environmental Engineering | en_US |
| dc.contributor.chair | Aggarwal, Srijan | |
| dc.contributor.chair | Dev, Subhabrata | |
| dc.contributor.committee | Schiewer, Silke | |
| dc.contributor.committee | Schuette, Ursel |
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