The performance of sediment microbial fuel cells (SMFCs) in the field must be evaluated prior to their being relied on as a power source for sensor networks. Currently, the ability to perform such evaluation is limited. The goal of this work was to develop an autonomous, battery-powered, low-cost device (a remote sediment microbial fuel cell tester, or RSMFCT) that can evaluate the field performance of SMFCs charging capacitors in remote areas. The developed RSMFCT allows an SMFC to charge a capacitor between preset charge and discharge potentials and monitors anode and cathode potentials, capacitor potential, and temperature. The RSMFCT was tested at a remote location in the Hot Lake Research Natural Area, near Oroville, WA, USA and used to evaluate the optimum conditions for operating an SMFC. Using the recorded data, the average power and frequency of cycle were determined. We found that SMFCs deployed in Hot Lake operated optimally when charging a 5-F capacitor from 300 mV to 400 mV. Under these conditions, the SMFCs produced an average daily power of 10.28 mu W and required an average capacitor charging time of 3.08 hours. We conclude that the RSMFCT is practical for: 1) determining the optimum operation parameters, those that maximize the power output of SMFCs in field operation, and 2) reliably incorporating individual SMFCs as power sources for remote sensor networks by allowing the prediction of their power output and frequency of charge cycles. (C) The Author(s) 2016. Published by ECS. All rights reserved.

In order for agricultural systems to successfully mitigate and adapt to climate change there is a need to coordinate and prioritize next steps for research and extension. This includes focusing on "win-win" management practices that simultaneously provide short-term benefits to farmers and improve the sustainability and resiliency of agricultural systems with respect to climate change. In the Northwest U.S., a collaborative process has been used to engage individuals spanning the research-practice continuum. This collaborative approach was utilized at a 2016 workshop titled " Agriculture in a Changing Climate," that included a broad range of participants including university faculty and students, crop and livestock producers, and individuals representing state, tribal and federal government agencies, industry, nonprofit organizations, and conservation districts. The Northwest U.S. encompasses a range of agro-ecological systems and diverse geographic and climatic contexts. Regional research and science communication efforts for climate change and agriculture have a strong history of engaging diverse stakeholders. These features of the Northwest U.S. provide a foundation for the collaborative research and extension prioritization presented here. We focus on identifying research and extension actions that can be taken over the next 5 years in four areas identified as important areas by conference organizers and participants: (1) cropping systems, (2) livestock systems, (3) decision support systems to support consideration of climate change in agricultural management decisions; and (4) partnerships among researchers and stakeholders. We couple insights from the workshop and a review of current literature to articulate current scientific understanding, and priorities recommended by workshop participants that target existing knowledge gaps, challenges, and opportunities. Priorities defined at the Agriculture in a Changing Climate workshop highlight the need for ongoing investment in interdisciplinary research integrating social, economic, and biophysical sciences, strategic collaborations, and knowledge sharing to develop actionable science that can support informed decision-making in the agriculture sector as the climate changes.

Sediment microbial fuel cells (SMFCs) are being developed as potential energy sources where remote sensing and monitoring would be useful. Several energy harvesting techniques for SMFCs have emerged, but effects of these different strategies on startup, performance, and microbial community are not well understood. We investigated these effects by comparing a continuous energy harvesting (CEH) strategy with an intermittent energy harvesting (IEH) strategy. During startup, IEH systems immediately produced higher power and were cathode limited. CEH systems exhibited a gradual power increase and were anode-limited during startup. Both system types produced similar amounts of steady-state power, 1.5 mW ft−2 (16 mW m−2) when optimized. However, an IEH system using unoptimized settings could not be subsequently switched to optimal settings and produce expected power levels. The choice of energy harvester did not appear to significantly affect steady-state community structure. Anodes were dominated by γand δ-proteobacteria while αand γ-proteobacteria dominated cathodes. The results suggest performance and community structure are unaffected by energy harvesting strategy, but that startup conditions influence the initial amount of harvested energy and steady-state performance, suggesting future investigations into optimizing startup of these systems are critical for rapidly generating maximum power. © The Author(s) 2017. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0171703jes] All rights reserved.

Encompassing a range of agro-ecological systems and diverse geographic and climatic contexts, the Northwest region provides a unique opportunity to test a collaborative approach to assessing and prioritizing climate change mitigation and adaptation opportunities. At a 2016 workshop titled “Agriculture in a Changing Climate”, university faculty and students, crop and livestock producers, and individuals representing state, tribal and federal government agencies, industry, nonprofit organizations, and conservation districts worked together to define research and extension priorities for the future. Insights and priorities related to climate change mitigation and adaptation in the Northwest were defined at the workshop. In this white paper, we synthesize those priorities, coupling recommendations from participants with a review of current literature. The focus is on identifying research and extension actions that can be taken over the next five years. We review current scientific understanding of climate impacts and mitigation, vulnerabilities, and opportunities to adapt, and enumerate research and extension priorities in four areas: (1) cropping systems, (2) livestock systems, (3) decision support systems to help producers and others incorporate climate change considerations into longer-term decisions; and (4) partnerships and communication between researchers and stakeholders. Priorities articulated in this white paper highlight the need for ongoing investment and strategic collaboration and knowledge sharing to develop actionable science. Actionable science will be more effective if integrated with regional extension efforts, facilitating utilization of scientific knowledge by the agricultural industry as the climate changes.

•Doping an electron donor onto the anode allowed quicker power generation and a higher maximum power.•However, when we compared long-term performances, we found that the improvements were temporary.•The differences in community structure made no difference in power generation.

Recently, some bacterial biofilms have been shown to colonize and transfer their extracellular electrons to solid electrodes in microbial fuel cells and in bioelectrochemical systems [1, 2]. This class of microorganisms is described as electrochemically active biofilms (EABs) that are able to transfer electrons outside the cell to insoluble electron acceptors (iron or metal oxides) or to solid electrodes via extracellular electron transfer [3, 4]. The need to understand the distribution of proteins involved in electron transfer in EABs is of critical importance. These proteins can be identified using mass spectroscopy (MS). It is known that there is a wide spectrum of applications in which mass spectroscopy (MS) can provide information from a sample of EABs, and these applications can easily translate to all areas of research in EABs. However, the spatial diversity of microbial functions within EABs cannot be resolved because all of the current MS analysis techniques are conducted in the bulk liquid, which provides no spatial resolution with respect to the structure of EABs. Separation techniques can be combined with MS to present a more focused data set with regard to composition; however, MS analysis still lacks the capacity to investigate variation with depth of EABs. Depth profiles will have the potential to elucidate the mechanisms of the surrounding matrix and the roles of the microorganism with respect to the layers of EABs and the growth interface. To date, this MS technique has not been used for depth profiling in EABs. This is mostly because there was no tool available to extract samples from different depths in EABs. Microcapillaries with a several-micrometer tip diameter can be used in EABs without damaging its structure for the depth profiling of selected chemicals. The goal of this work was to develop a microcapillary system which can extract samples at desired depth inside the EABs. Ambient pressure surface ionization mass spectrometry is used to obtain a chemical analyte for sampling from interfaces without special sample preparation [5]. Desorption electrospray ionization (DESI) is an ambient ionization technique in which charged droplets from an electrosonic spray ionization source are aimed towards a surface with a proximal atmospheric pressure mass spectrometer inlet. In this technique, analyte molecules are collected from flat surfaces followed by ionization using a self-aspirating nanoelectrospray. This technique directly transports and ionizes an analyte that is desorbed from a surface into a liquid and it is called as nanospray DESI (nano-DESI). The nanospray capillary transports the charged liquid to the mass spectrometer inlet directly, eliminating splashing while minimizing analyte transport distance. The target application of the developed microcapillary system is to interface it with a nano-DESI sensor which can be used to characterize in situ, depth-resolved analyses of metabolites and possibly proteins. The developed nano-DESI sensor is composed of two microcapillaries placed in an outer case made of glass. Figure 1 shows an image of a developed nano-DESI sensor. In this system, the solvent delivery and its collection were made from the same microcapillaries. We managed to operate the sensor between 10 nL/min and 100 mL/min flow rates. After optimization of the flow rates, we tested it in EABs. EABs were grown according to our previously published paper and book [6, 7]. While we had succeeded in developing a nano-DESI sensor, we found unexpected challenges using it with EABs. Finally, the microcapillary system developed for this work enabled us to use it for quantifying electron transfer processes in EABs [7]. References: 1. Hamelers, H.M., et al., New applications and performance of bioelectrochemical systems. Applied Microbiology and Biotechnology, 2010. 85(6): p. 1673-1685. 2. Logan, B.E., Exoelectrogenic bacteria that power microbial fuel cells. Nat Rev Micro, 2009. 7(5): p. 375-381. 3. Lovley, D.R., Microbial fuel cells: novel microbial physiologies and engineering approaches. Current Opinion in Biotechnology, 2006. 17(3): p. 327-332. 4. Logan, B.E., et al., Microbial Fuel Cells: Methodology and Technology†. Environmental Science & Technology, 2006. 40(17): p. 5181-5192. 5. Roach, P.J., J. Laskin, and A. Laskin, Nanospray desorption electrospray ionization: an ambient method for liquid-extraction surface sampling in mass spectrometry. Analyst, 2010. 135(9): p. 2233-2236. 6. Lewandowski, Z. and H. Beyenal, Fundamentals of Biofilm Research, Second Edition. 2014: Taylor & Francis. 7. Babauta, J.T. and H. Beyenal, Local Current Variation by Depth in Geobacter Sulfurreducens Biofilms. Journal of The Electrochemical Society, 2014. 161(13): p. H3070-H3075. Figure 1

Sediment microbial fuel cells (SMFCs) are considered a promising renewable power source for remote monitoring applications. However, existing SMFCs can only produce several milliwatts of power, and the output power is not scaled linearly with the size of SMFCs. An effective alternative method to increase the output power is to independently operate multiple SMFCs, each of which has an optimal size for maximum power density. Independently operated SMFCs have electrically isolated electrodes (anodes/cathodes), which complicates the design of a suitable power management system (PMS). This paper describes the challenges in designing a PMS that can harvest energy from multiple independently operated (mio) SMFCs and accordingly proposes a design solution. From experimental results, the proposed PMS demonstrates reliable output power scaling up of mio-SMFC. The proposed PMS is self-sustainable because it is powered entirely from harvested energy without requiring additional external power sources.

Sediment microbial fuel cells (SMFCs) are used as renewable power sources to operate remote sensors. However, increasing the electrode surface area results in decreased power density, which demonstrates that SMFCs do not scale up with size. As an alternative to the physical scale-up of SMFCs, we proposed that it is possible to scale up power by using smaller-sized individually operated SMFCs connected to a power management system that electrically isolates the anodes and cathodes. To demonstrate our electronic scale-up approach, we operated one 0.36-m(2) SMFC (called a single-equivalent SMFC) and four independent SMFCs of 0.09 m(2) each (called scaled-up SMFCs) and managed the power using an innovative custom-developed power management system. We found that the single-equivalent SMFC and the scaled-up SMFCs produced similar power for the first 155 days. However, in the long term (>155 days) our scaled-up SMFCs generated significantly more power than the single-equivalent SMFC (233 mW vs. 0.64 mW). Microbial community analysis of the single-equivalent SMFC and the scaled-up SMFCs showed very similar results, demonstrating that the difference in operation mode had no significant effect on the microbial community. When we compared scaled-up SMFCs with parallel SMFCs, we found that the scaled-up SMFCs generated more power. Our novel approach demonstrates that SMFCs can be scaled up electronically. (C) 2014 Elsevier B.V. All rights reserved.

The goal of this study was to harness the redox gradients in facultative lagoons using a lagoon microbial fuel cell (LMFC) to enhance autonomously the delivery of oxygen to the lagoon through aeration and mixing by operating an air pump. To enhance the usability of the low power generated by the LMFC, a power management system (PMS) was used to harvest power continually while only operating the air pump intermittently. Here we demonstrate the LMFC as an alternative energy source for self-powered wastewater treatment systems by treating both artificial wastewater and dairy wastewater in large laboratory-scale simulated lagoons. For comparison, we also used a lagoon treatment system without self-aeration. We show that the integrated LMFC and PMS system was able to improve chemical oxygen demand (COD) removal time by 21% for artificial wastewater and by 54% for dairy wastewater. The LMFC-PMS wastewater treatment system operated for over a year and proved to be robust and provide a measure of sustainability. The LMFC-PMS combination offers an innovative and low-tech approach to increasing the capacity of lagoons for rural communities. We believe that the technology developed in this research is the first step towards providing sustainable self-powered wastewater treatment systems.

Phototrophic microbial mats frequently exhibit sharp, light-dependent redox gradients that regulate microbial respiration on specific electron acceptors as a function of depth. In this work, a benthic phototrophic microbial mat from Hot Lake, a hypersaline, epsomitic lake located near Oroville in north-central Washington, was used to develop a microscale electrochemical method to study local electron transfer processes within the mat. To characterize the physicochemical variables influencing electron transfer, we initially quantified redox potential, pH and dissolved oxygen gradients by depth in the mat under photic and aphotic conditions. We further demonstrated that power output of a mat fuel cell was light-dependent. To study local electron transfer processes, we deployed a microscale electrode (microelectrode) with tip size ~20 µm. To enrich a subset of microorganisms capable of interacting with the microelectrode, we anodically polarized the microelectrode in the mat. Subsequently, to characterize the microelectrode-associated community and compare it to the neighboring mat community, we performed amplicon sequencing of the V1-V3 region of the 16S gene. Differences in Bray-Curtis beta diversity, illustrated by large changes in relative abundance at the phylum level, suggested successful enrichment of specific mat community members on the microelectrode surface. The microelectrode-associated community exhibited substantially reduced alpha diversity and elevated relative abundances of Prosthecochloris, Loktanella, Catellibacterium, other unclassified members of Rhodobacteraceae, Thiomicrospira, and Limnobacter, compared with the community at an equivalent depth in the mat. Our results suggest that local electron transfer to an anodically polarized microelectrode selected for a specific microbial population, with substantially more abundance and diversity of sulfur-oxidizing phylotypes compared with the neighboring mat community.

Co-digestion of dairy manure with off-farm waste has become a common practice on US farms, however, little data at a commercial-scale is present within the literature. In response, a mesophilic, mixed plug-flow reactor co-digesting 16.36% v/v food processing substrates with dairy manure, was monitored for its performance and substrate effects. Co-digestion, as compared to substrate or manure-only digestion, allowed for more preferred levels of key micronutrients, neutral pH, and additional alkalinity while also producing C/N and C/N/P ratios of 28:1 and 112:4:0.5, respectively. Reduction percentages were 45.36, 55.28, 67.72, and 99.87% for TS, VS, COD, and VFA, respectively, while fecal coliform bacteria as an indicator organism showed a 2 log(10) reduction. A manure-only modeled baseline was developed for comparison with the experimental co-digestion data with co-digestion resulting in a 110% increase in biogas production and a tripling of gross receipts with 72% of all receipts being directly due to substrate supplementation. Specific methane productivities for the manure-only and co-digestion scenarios were 0.23 and 0.37m(3) CH(4)/kg VS(load), respectively. Addition of substrates tripled project gross revenues and accounted for 72% of all receipts, however, inclusion of substrates led to significant increases in total nitrogen and phosphorous loading to the farm.

United States is experiencing increasing interests in fermentation and anaerobic digestion processes for the production of biofuels. A simple methodology of spatial biomass assessment is presented in this paper to evaluate biofuel production and support the first decisions about the conversion technology applications. The methodology was applied to evaluate the potential biogas and ethanol production from biomass in California and Washington states. Solid waste databases were filtered to a short list of digestible and fermentable wastes in both states. Maximum methane and ethanol production rates were estimated from biochemical and ultimate analysis of each waste and projected on a GIS database. Accordingly, the optimal locations for methane and ethanol production plants were approximately determined. The available net power for transportation and electricity generation was evaluated considering three process efficiency factors in the waste to power life cycle. The net power from methane and ethanol would ultimately cover ~ 6 8% of the transportation needs for motor gasoline or cover ~ 3 4% of the electrical power consumption in each state.

Effect of Location on the Performance of Benthic Microbial Fuel CellsThe lifetime of remote sensors is often limited by battery power. Replacing batteries is costly and time-consuming, and it may be impractical when the sensors are deployed at remote locations. Benthic microbial fuel cells (BMFCs) constitute a promising alternative power source that may replace or supplement batteries. In this study we investigated power generation by BMFCs deployed in coastal...Author(s)Alim DewanTimothy EwingMark E. NielsenClare E. ReimersBart ChadwickKen RichterZbigniew LewandowskiHaluk BeyenalSourceProceedings of the Water Environment FederationSubjectSession 1: Microbial Fuel CellsDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2010ISSN1938-6478SICI1938-6478(20100101)2010:7L.48;1-DOI10.2175/193864710798208520Volume / Issue2010 / 7Content sourceResiduals and Biosolids ConferenceFirst / last page(s)48 - 51Copyright2010Word count182Subject keywordsMicrobial fuel cellremote sensorsrenewable power generation

Co-digestion is a widely used protocol for biologically stabilizing wastewaters and waste solids that otherwise might be sent to alternative disposal sites such as landfills. The number of applications is growing, within both farm (Frear et al., 2009) and municipal digester (Wallis et al., 2008; Zupancic et al., 2008) applications. In many cases, one of the motivations for practicing co-digestion is to better exploit under-utilized digesters and to bring in added income to the facility through received tipping fees. Problems can occur, though, with co-digestion, particularly in regard to: