Living Filtration Membranes (LFMs) are a water filtration technology that was recently developed in the lab (Technology Readiness Level 4). LFMs have shown filtration performance comparable with that ...of ultrafiltration, far better fouling resistance than conventional polymer membranes, and good healing capabilities. These properties give LFMs promise to address two significant issues in conventional membrane filtration - fouling and membrane damage. To integrate environmental considerations into future technology development (i.e., Ecodesign), this study assesses the life cycle environmental performance of LFMs treating drinking water under likely design and operation conditions. It also quantitatively ranks the engineering design and operation factors governing the further optimization of LFMs' environmental performance using a global sensitivity analysis. The results suggest that LFMs' superior fouling resistance will reduce the life cycle environmental impacts of ultrafiltration by 25% compared to a conventional polymer membrane in most impact categories (e.g., Acidification, Global Warming Potential and Carcinogenics). The only exception is the eutrophication impacts, where the need for growth medium and membrane regeneration offsets the benefits of LFMs' fouling resistance. Permeability is the most important factor that should be prioritized in future R&D to further improve LFMs' life cycle environmental performance. A 1% improvement in the permeability will lead to a ~0.7% improvement in LFMs' environmental performance in all the impact categories, whereas the same change in the other parameters investigated (e.g. LFM lifespan and regeneration frequency) typically only leads to a <0.2% improvement.
In this study, two novel electrode materials were tested to enhance bacterial adhesion and increase power production in microbial fuel cells (MFCs). Polypyrrole (PPy), a nontoxic conductive polymer, ...was coated on the plain carbon cloth electrodes to bridge with the biopolymers on bacterial cell membranes and to improve the power production. The PPy-coated electrodes increased the initial power from 20 mW/m(2) to 160 mW/m(2) in the first 4-day period. But there was no clear difference between two PPy coating thicknesses (5-cycle coating and 50-cycle coating) in terms of the bacterial adhesion and power production. Granular activated carbon (GAC), a commonly used bacterial support material with high surface area, exhibited a good bacterial adhesion and high power output. GAC-SCMFCs (single chamber MFCs) generated 5 W/m(3) and maintained the peak power for 6 days. Compared with plain carbon cloth electrodes, GAC-SCMFCs had lower internal resistances and higher power generations. However, GAC-SCMFCs had lower columbic efficiency and energy conversion efficiency than the conventional two chamber MFCs.
Scheduling pipe replacement is critical for water distribution systems (WDSs) when managing finances and water loss. WDS replacements are often delayed due to high immediate costs without considering ...long‐term environmental consequences. This study is the first to examine a real‐world WDS using a novel workflow transferrable to other WDSs that integrates GIS, hydraulic modeling, breakage prediction, and life cycle analysis to evaluate environmental impacts and water loss of five replacement schedules (25‐, 50‐, 75‐, 100‐, 150‐year intervals). Environmental impacts were reduced by half when replacement interval changed from 25 year to 150 years, yet volume of water leaked from the system quadrupled. Benefits plateaued beyond 50–75‐year replacement while water loss steadily increased. Lowering water loss through break management enabled one‐sixth pipe replacement without exceeding original leakage at 25‐year replacement. Results were robust to uncertainty parameters and assert the importance of equilibrating environmental impacts and water loss when designing pipe replacement frequency.
The Funding Statement should read: "The authors wish to thank the National Natural Science Foundation of China (41373073) and Zhejiang Science and Technology Program (2011F20025) for providing the ...financial support for this project. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Microbial Fuel Cell is a next-generation biofuel that could contribute to the energy sustainability. The objective of this study is to develop a multi-anode/cathode MFC to increase the power ...production and demonstrate the viability of MFCs in real-world applications. Lab-scale studies demonstrated that increasing the number of electrodes increased the power production and 4-anode/cathode MFCs produced higher power densities than 2-anode/cathode MFCs. Based on the success of lab-scale studies, pilot-scale 12-anode/cathode MFC systems were developed and operated treating wastewater in Johnstown Wastewater Treatment Plant. Multi-anode/cathode MFCs exhibited a good power production and COD removal on wastewater. The upflow and downflow modes were compared and no significant difference was found in terms of the power output and COD removal. Upflow mode was employed in later MFCs to prevent clogging of the reactor. The power density of multi-anode/cathode MFCs achieved 0.4 W/m 2 and the COD removal was 80% when operated on real wastewater. The power production of MFCs demonstrated an increase (0.3 to 0.4 W/m2 ) as the organic loading rate increased (0.19 to 0.66 kgCOD/m 3/d). In one MFC, 8 of the 12 anode/cathode pairs were disconnected and the 4-anode/cathode MFC was operated for four weeks to confirm the effect of increasing the number of electrodes. The 12-anode/cathode MFCs produced the equivalent power density per channel as the 4-anode-anode/cathode MFC, indicating that increasing the number of electrodes could effectively increase the total power production of MFCs. 30% TKN removal but minimal total phosphorus removal was achieved by multi-anode/cathode MFCs. High total solids removal was achieved due to the use of granular activated carbon bed. Cathode fouling was noticed as a problem that severely lowered the power output and increased the internal resistance of MFCs. Fouling deposits were analyzed and the results suggested that the interior cathode fouling was caused by CaCO3 and the exterior fouling was caused by diffusion of water through cathodes. Finally, an economic analysis revealed that the capital cost of MFCs needs to be reduced and the power harvested from MFCs needs to be increased to make MFCs an economic technology for wastewater treatment applications.
Rational utilization of reluctance torque can effectively improve torque performance and speed range in constant power region of interior permanent magnet(IPM) electric machines, thereby affecting ...dynamic performance of HEVs. This paper presents a reluctance torque analysis method on the basis of calculating the torque-power angle characteristic curve in advantage of FEM. Moreover, the direct(d) and quadrature(q) axis synchronous reactance is calculated. Furthermore, a measure of improving flux weakening performance by increasing salient-pole rate is proposed. The prototype experiment results verify this analysis method. The method presented in this paper provides reference for electromagnetic design of traction motors in HEVs.
Agricultural fertilization may change processes of elemental biogeochemical cycles and alter the ecological function. Ecoenzymatic stoichiometric feature plays a critical role in global soil carbon ...(C) metabolism, driving element cycles, and mediating atmospheric composition in response to agricultural nutrient management. Despite the importance on crop growth, the role of phosphorous (P) in compliance with eco-stoichiometry on soil C and nitrogen (N) sequestration in the paddy field remains poorly understood in the context of climate change. Here, we collected soil samples from a field experiment after 6 years of chemical P application at a gradient of 0 (P-0), 30 (P-30), 60 (P-60), and 90 (P-90) kg ha-1 in order to evaluate the role of P on stoichiometric properties in terms of soil chemical, microbial biomass, and eco-enzyme activities as well as greenhouse gas (GHG: CO2, N2O and CH4) emissions. Continuous P input increased soil total organic C and N by 1.3-9.2% and 3%-13%, respectively. P input induced C and N limitations as indicated by the decreased ratio of C:P and N:P in the soil and microbial biomass. A synergistic mechanism among the ecoenzymatic stoichiometry, which regulated the ecological function of microbial C and N acquisition and were stoichiometrically related to P input, stimulated soil C and N sequestration in the paddy field. The lower emissions of N2O and CH4 under the higher P application (P-60 and P-90) in July and the insignificant difference in N2O emission in August compared to P-30; however, continuous P input enhanced CO2 fluxes for both samplings. There is a technical conflict for simultaneously regulating three types of GHGs in terms of the eco-stoichiometry mechanism under P fertilization. Thus, it is recommended that the P input in paddy fields not exceed 60 kg ha-1 may maximize soil C sequestration, minimize P export, and guarantee grain yields.
Soil biogeochemical processes and the ecological stability of wetland ecosystems under global warming scenarios have gained increasing attention worldwide. Changes in the capacity of microorganisms ...to maintain stoichiometric homeostasis, or relatively stable internal concentrations of elements, may serve as an indicator of alterations to soil biogeochemical processes and their associated ecological feedbacks. In this study, an outdoor computerized microcosm was set up to simulate a warmed (+5 degree C) climate scenario, using novel, minute-scale temperature manipulation technology. The principle of stoichiometric homeostasis was adopted to illustrate phosphorus (P) biogeochemical cycling coupled with carbon (C) dynamics within the soil-microorganism complex. We hypothesized that enhancing the flux of P from soil to water under warming scenarios is tightly coupled with a decrease in homeostatic regulation ability in wetland ecosystems. Results indicate that experimental warming impaired the ability of stoichiometric homeostasis (H) to regulate biogeochemical processes, enhancing the ecological role of wetland soil as an ecological source for both P and C. The potential P flux from soil to water ranged from 0.11 to 34.51 mg m-2 d-1 in the control and 0.07 to 61.26 mg m-2 d-1 in the warmed treatment. The synergistic function of C-P acquisition is an important mechanism underlying C:P stoichiometric balance for soil microorganisms under warming. For both treatment groups, strongly significant (p<0.001) relationships fitting a negative allometric power model with a fractional exponent were found between n-HC:P (the specialized homeostatic regulation ability as a ratio of soil highly labile organic carbon to dissolved reactive phosphorus in porewater) and potential P flux. Although many factors may affect soil P dynamics, the n-HC:P term fundamentally reflects the stoichiometric balance or interactions between the energy landscape (i.e., C) and flow of resources (e.g., N and P), and can be a useful ecological tool for assessing potential P flux in ecosystems.
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