A. James Clark School of Engineering
Permanent URI for this communityhttp://hdl.handle.net/1903/1654
The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item PREVENTION AND TREATMENT OF PERSISTENT ORGANIC POLLUTANTS IN STORMWATER AND SEDIMENT(2023) Yuan, Chen; Kjellerup, Birthe V; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Polycyclic aromatic hydrocarbons (PAHs) and Polychlorinated biphenyls (PCBs) are two groups of persistent organic pollutants (POPs) with toxicity, carcinogenicity, and teratogenicity. Those compounds are harmful to human health and wildlife. Stormwater is one of the important sources of PAHs and PCBs to aquatic environments. Stormwater control measures (SCMs) have already been used to remove PAHs and PCBs from stormwater, however traditional SCMs can remove PAHs and PCBs in the particle phase, but there still are dissolved PAHs and PCBs in the outflow of SCMs. This study focused on reducing the influence of PAHs and PCBs in stormwater on the environment by 1) improve the treatment performance by adding a polishing treatment procedure after traditional SCMs, and remove the PAHs and PCBs accumulated in the polishing treatment media by bioaugmentation of Pseudomonas putida ATCC 17484 and Paraburkholderia xenovorans LB400 and 2) dechlorination of PCBs in the sediment of aquatic environments by biofilm Dehalobium chlorocoercia DF1 inoculum. The results of polishing treatment showed that all black carbon materials, namely biochar, granular activated carbon (GAC), and regenerated GAC (RAC), were effective to remove dissolved PAHs with removal > 95%. However, all materials had lower removal efficiency on PCBs with removal > 84%, By the comparation of cost and lifetime under the condition that 50% polishing media are used in the polishing treatment facility. RAC which has a lifetime>147 years based on the precipitation of Maryland and Washington and cost <3.79 $-m3-yr-1, was the best material for polishing treatment. Results of treatment train with a traditional SCM media column and polishing treatment column indicated that average removal of PAHs can be improved from 94.56% of BSM columns to 99.61% of polishing treatment columns, and removal of PCBs can be improved from 84.61% to 95.16%. Results of bioaugmentation of polishing treatment media showed no biodegradation took place in the mesocosms with polishing media. However, the liquid mesocosms showed P.putida degraded 97.9% of pyrene. The bacteria colony on plates after the biodegradation experiment showed that there were less P.putida and P.xenovorans colony of polishing media mesocosms than liquid mesocosms. Therefore, the limitation of biodegradation of polishing media mesocosms may cause by the limited bioavailability and less active inoculated bacteria. The results of dechlorination by Dehalobium chlorocoercia DF1 biofilm shows that there were native bacteria, such as Gemmatimonadetes, Actinobacteria, Proteobacteria and Firmicutes in the sediment that can dechlorinate PCBs. The three treated mesocosm groups (addition of biochar, bioaugmentation with DF1 biofilm and liquid DF1 culture) all can improve dechlorination, of 28.09%, 21.30%, and 17.10%, respectively. Those three groups had dechlorination extent higher than negative control (4.60%), and abiotic control (-1.02%). The microbial community analysis indicated that biofilm inoculation improved abundance of DF1 and had a more stable influence on the community than liquid inoculation. Overall, biofilm inoculation and addition of biochar dechlorinate PCBs in sediment efficiently, and polishing treatment is an efficient approach to improve traditional SCMs, while treating the polishing media with bioaugmentation need further study.Item INTEGRATED MICROSYSTEM-BASED APPROACH FOR DETECTION AND TREATMENT OF BACTERIAL BIOFILMS ON URINARY CATHETERS(2020) Huiszoon, Ryan Cornelis; Ghodssi, Reza; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Biofilms are a ubiquitous mode of growth for bacteria and present a significant challenge in healthcare due to their resistant nature towards traditional antibiotic therapy. Particularly, biofilms can form on indwelling urinary catheters, leading to catheter-associated urinary tract infections, which are one of the most prevalent healthcare-acquired infections. In recent years, microsystems-based approaches have been developed to measure and study bacterial biofilms. In this dissertation, microsystems are adapted for the catheterized urinary tract environment to address biofilm infections in situ. Specifically, a proof-of-concept device comprised of gold interdigitated electrodes on a flexible polyimide substrate is fabricated and characterized in vitro. This substrate allows the device to conform seamlessly with the cylindrical surface of a catheter. Real-time impedance sensing is demonstrated, showing an average decrease in impedance of 30.3% following 24 hours of biofilm growth. The device also applies the bioelectric effect, which yields an increase in impedance of 12% and the lowest biomass relative to control treatments. Furthermore, 3D-printed molds and commercial modeling software show that the cylindrical conformation does not have an appreciable impact on performance. This device is integrated with a commercially available Foley catheter using two disparate approaches: (1) integration of the flexible proof-of-concept device using a 3D-printed catheter insert and (2) electroless plating directly onto the catheter lumen. In addition to electrode integration, miniaturized electronic systems are developed to control sensing and treatment wirelessly with a minimal form factor. A smartphone mobile application is developed in conjunction with this effort, to provide a user-friendly interface for the system. Several functions are verified with the integrated system, including biofilm sensing, wireless signal transmission, bladder drainage, and balloon inflation. To decrease the risk associated with this system for future research in vivo and in a clinical setting, sensing and treatment are evaluated under realistic conditions. The biochemical aspect of the catheterized environment is recreated using artificial urine, and the physical aspect is recreated using a silicone model of a human bladder and a programmable pump. A 13.0% decrease in impedance is associated with bacterial growth; this decreased magnitude relative to the proof-of-concept device is due to the reduced degree of growth in artificial urine. The bioelectric effect is demonstrated as well, showing a reduction in planktonic bacteria of 1.50×107 CFU/ml and adhered biomass equivalent to OD590nm = 0.072 relative to untreated samples. This work provides a framework for developing microsystem-based tools for biofilm infection management and research from proof-of-concept to integrated system, particularly for CAUTI. The results demonstrate that the cylindrical conformation does not interfere with device sensing or treatment performance and that the system maintains functionality under realistic conditions, laying the groundwork for future in vivo and clinical testing. The system will provide in situ and real-time data regarding catheter biofilm colonization in a way that is not possible with existing techniques. Finally, the system can serve to reduce reliance on antibiotics and reduce the spread of antibiotic resistance in CAUTI and other vulnerable areas.Item Evaluation of treatment and resource recovery potential of bioelectrochemical systems to DC Water process streams by bench and pilot system(2018) Leininger, Aaron Matthew; Kjellerup, Birthe V; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Microbial fuel cell and microbial electrolysis cell systems were developed and tested with different wastewater process streams from DC Water Blue Plains Advanced Wastewater Treatment Plant. These biofilm-based systems provide an alternative to the conventional activated sludge system by oxidizing wastewater organics without the need for mechanical aeration. In bench-scale systems, the application of high-strength solids-dewatering wastewater as a feedstock was shown to increase both treatment energy savings and energy recovery. Current densities in meso-scale microbial electrolysis cells were 3.3 and 3.6 times higher when fed dewatering-filtrate or a blend of filtrate and primary effluent as compared to reactors operating with primary effluent. An integrated 800L pilot biocathode microbial fuel cell system was designed and constructed, and initial results are reported. Over the first 43 days of operation, the system averaged 15% removal of chemical oxygen demand and a load removal of 110 g_tCOD/(m^3*day).Item Design and Implementation of Microfluidic Systems for Bacterial Biofilm Monitoring and Manipulation(2014) Meyer, Mariana; Ghodssi, Reza; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bacterial biofilms - pathogenic matrices formed through bacterial communication and subsequent extracellular matrix secretion - characterize the majority of clinical bacterial infections. Biofilms exhibit increased resistance to conventional antibiotics, necessitating development of alternative treatments. Standard microbiological methods for studying biofilms often rely on in vitro systems with involved instrumentation for biofilm quantification, or destroy the biofilm in the process of characterization. Additionally, biofilm formation is sensitive to many growth parameters, and can exhibit a large degree of variability between repeated experiments. This dissertation presents the development of systems designed to address these challenges through integration of continuous biofilm monitoring in a microfluidic platform, and through creation of a microfluidic platform for multiple assays performed on one biofilm formed in a single channel. The microsystems developed in this work provide building blocks for developing controlled, high throughput testbeds for development and evaluation of drugs targeting bacterial biofilms. The first platform developed relied on optical density monitoring as a means for evaluating biofilm formation. This method was noninvasive, as it used an external light source and array of photodiodes to evaluate biofilms by the amount of light transmitted through the microfluidic channel where they were grown. The optical density biofilm measurement method and microfluidic platform were used to evaluate the dependence of biofilm formation on quorum sensing, an autoinducer-mediated intercellular communication process. This system was also used in the first demonstration of biofilm inhibition and reduction by two different autoinducer-2 analogs. The second microfluidic system developed addressed the challenge of variability in biofilm formation. Biofilms formed in a single microfluidic channel were partitioned by hydraulically actuated valves into three separate segments, which were then treated as representatives of the original biofilm in further experiments. A novel photoresist passivation process was developed in order to create the multi-depth channels needed to accommodate both valve actuation and biofilm formation. Biofilms grown in the device were uniform throughout, providing reliable experimental controls within the system. Biofilm partitioning was demonstrated by exposing three segments of one biofilm to varying detergent concentrations.