Scholarship & Research
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Item The microbial fuel cell as an educational tool(2010) Dewan, Alim; Van Wie, B.; Beyenal, Haluk; Lewandowski, ZbigniewAccording to Accreditation Board for Engineering and Technology (ABET) outcome 3d, graduates from engineering programs must have the ability to function on multidisciplinary teams. Unfortunately, evaluation shows that engineering students are not well positioned to understand new concepts from a variety of disciplines and integrate them into what they learn in their own disciplines. This is especially true for concepts in emerging areas, such as life sciences. Obviously the emergence of technological breakthroughs in new arenas is stimulating faculty members to include related multidisciplinary concepts in their course designs so that students can be prepared to meet the industrial challenges presented in applying new technologies within industrial settings.Item Biofilm image reconstruction for assessing structural parameters(2011-06) Renslow, Ryan; Lewandowski, Zbigniew; Beyenal, HalukThe structure of biofilms can be numerically quantified from microscopy images using structural parameters. These parameters are used in biofilm image analysis to compare biofilms, to monitor temporal variation in biofilm structure, to quantify the effects of antibiotics on biofilm structure and to determine the effects of environmental conditions on biofilm structure. It is often hypothesized that biofilms with similar structural parameter values will have similar structures; however, this hypothesis has never been tested.The main goal was to test the hypothesis that the commonly used structural parameters can characterize the differences or similarities between biofilm structures. To achieve this goal (1) biofilm image reconstruction was developed as a new tool for assessing structural parameters, (2) independent reconstructions using the same starting structural parameters were tested to see how they differed from each other, (3) the effect of the original image parameter values on reconstruction success was evaluated, and (4) the effect of the number and type of the parameters on reconstruction success was evaluated. It was found that two biofilms characterized by identical commonly used structural parameter values may look different, that the number and size of clusters in the original biofilm image affect image reconstruction success and that, in general, a small set of arbitrarily selected parameters may not reveal relevant differences between biofilm structures.Item Membrane fouling due to dynamic particle size changes in the aerated hybrid PAC–MF system(2011-04) Khan, Mohiuddin M. T.; Takizawa, S.; Lewandowski, Zbigniew; Jones, Warren L.; Camper, Anne K.; Katayama, H.; Ohgaki, S.To quantify the effect of dynamic particle size changes and degradation and accumulation of suspended solids (SS) in influents to reactors on membrane fouling frequency in hybrid powder-activated carbon (PAC)–microfiltration (MF) reactors, we operated a PAC–MF system (hollow-fiber module) for more than five months to purify river water before and after pretreatment by a biofilter. The transmembrane pressure, backwashing pressure, resistance to filtration, and SS accumulation and degradation during these dynamic changes were evaluated. The initial dose of PAC was 40 g/L of the reactor and no additional PAC was added during this continuous operational period. The presence of PAC reduced the membrane resistance to filtration even at the end of filtration period when the number of particles in the smallest range (>1.0–3.6 μm) was the highest measured by the flow cytometer and microscopy image analysis. This resistance was reduced further when the river water was biofiltered prior to membrane filtration. This real-time study demonstrates that over time PAC and other particles coming into the reactors through the influents degrade and/or become smaller because of the turbulence caused by continuous aeration below the MF membrane fibers. The number of particles in the reactors with diameters less than 10 μm increased with time, increasing the fouling frequency; however, the presence of PAC further reduced the particle enhanced fouling. The presence of PAC also increased SS degradation by up to 10%. The increased number of bacteria inside the PAC–MF systems did not contribute to the number of membrane fouling. Even though the particle sizes inside the reactors became smaller with time, the gradual increase in net accumulation of SS was also an important factor controlling the performance of the PAC–MF system.Item Electrochemically active biofilms: Facts and fiction. A review(2012-09) Babauta, J.; Renslow, Ryan; Lewandowski, Zbigniew; Beyenal, HalukThis review examines the electrochemical techniques used to study extracellular electron transfer in the electrochemically active biofilms that are used in microbial fuel cells and other bioelectrochemical systems. Electrochemically active biofilms are defined as biofilms that exchange electrons with conductive surfaces: electrodes. Following the electrochemical conventions, and recognizing that electrodes can be considered reactants in these bioelectrochemical processes, biofilms that deliver electrons to the biofilm electrode are called anodic, ie electrode-reducing, biofilms, while biofilms that accept electrons from the biofilm electrode are called cathodic, ie electrode-oxidizing, biofilms. How to grow these electrochemically active biofilms in bioelectrochemical systems is discussed and also the critical choices made in the experimental setup that affect the experimental results. The reactor configurations used in bioelectrochemical systems research are also described and the authors demonstrate how to use selected voltammetric techniques to study extracellular electron transfer in bioelectrochemical systems. Finally, some critical concerns with the proposed electron transfer mechanisms in bioelectrochemical systems are addressed together with the prospects of bioelectrochemical systems as energy converting and energy-harvesting devices.Item Sediment microbial fuel cell powering a submersible ultrasonic receiver: New approach to remote monitoring(2013-07) Donovan, C.; Dewan, Alim; Heo, D.; Lewandowski, Zbigniew; Beyenal, HalukThe goal of this study was to develop a power management system (PMS) that could power a submersible ultrasonic receiver (SUR) continuously to keep accurate time and listen to ultrasonic signals when there was enough energy for a complete scan. We developed a PMS and modified the hardware and firmware of the SUR to allow it to be controlled by our PMS. Thus, the SUR became optimized for the SMFC and was controlled by the PMS. The SUR switched to idle mode without stopping the RTC when there was not enough energy for a complete scan. The PMS used a 350-F capacitor to store microbial energy. The SMFC was deployed in the Palouse River, Pullman, WA. The integrated PMS was tested and operated the SUR continuously for six weeks. Our integrated PMS and sensor could make SMFCs a more viable renewable power source for continuous environmental monitoring. We found that the SUR could only be powered continuously if its operation was controlled by the PMS. We believe that future applications of more complex sensors could benefit from our novel approach of controlling the sensor using the PMS for uninterrupted operation even when the data are collected intermittently.