Tubular Microbial Fuel Cell Systems For Decentralized Wastewater Treatment and Soil Remediation

Critical natural resources, upon which all lives largely depend, are susceptible to detrimental consequences due to environmental pollution. Microbial fuel cells (MFCs) could be leveraged in the treatment of environmental pollutants while simultaneously producing bioelectricity. Therefore, the overarching objective of this study was to develop a tubular MFC system for effective and efficient decentralized wastewater treatment and soil remediation. Septic tanks and other decentralized wastewater treatment systems play an important role in protecting public health and water resource for remote or developing communities. Current systems do not have energy production capability, yet such feature can be very valuable for areas lack access to electricity. To solve this problem, we designed an easy-to-operate microbial fuel cell (MFC) stack that consists a common base and multiple pluggable units, which can be connected in either series or parallel for electricity generation during waste treatment in septic tanks. Lab studies showed such easy configuration obtained a power density of 142&plusmn;6.71 mW.m-2 when 3 units are connected in parallel, and preliminary calculations indicated that a system that costs approximately US $25 can power a 6-watt LED light for 4 hours per day with improvement potential. With the success of tubular decentralized MFC configuration, we hypothesized that it can also be used in remote areas for hydrocarbon-contaminated soil remediation. The remediation of crude oil using tubular MFCs was also investigated over the course of 284 days to test the long term operation performance. The results demonstrated simultaneous removal of petroleum hydrocarbons (&gt; 30 %), and electricity production was sustained with the peak power density of up to 10.2 mW/m2 recorded. By comparing MFC-enhanced remediation with natural attenuation, we found that the crude oil removal can be increased by 50-200%, while the removal performance was correlated with the distance from the MFC tube. The reactor generated sustainable voltage that could serve as a proxy for remediation monitoring. Nutrient amendment significantly boosted further removal of crude oil, indicating the soil was nutrient limited, and redox potential monitoring suggested that the tubular MFC operation created a redox gradient that facilitated hydrocarbon removal. The tubular MFC system was further scaled to cubic meter scale with dynamic groundwater flow to simulate contaminant plume condition. When the MFC was placed downstream of the plume, the system showed excellent hydrocarbon removal, with the TPH removal in saturated zone ranged from 40-68%. During stable operation, the maximum power density was calculated as 8.2 mW/m2, which is comparable with bench scale reactors in the saturation condition. Decreasing soil saturation level from 100% to 50% significantly affected TPH removal and current generation, indicating moisture content is critical for MFC operation. In summary, MFC systems can be easily installed and operated for remote or decentralized environmental applications with energy output. This offers good application potentials for distributed and developing communities.</p

Impact of Speculative Bubble on Stock Returns in Companies Listed on Tehran Stock Exchange

Recent studies show that individual investors tend to speculate on stock markets and hold shares with a lottery-like return. For this speculation of people have a significant impact on stock returns, individual investors must trade the same shares with the same time. The purpose of this study was to investigate the effect of the speculative bubble on the stock returns of companies in Iran. Following the design of the speculative bubble specification indexes, the transaction information was collected from the stock market in the five-year period from 2011 to 2015 and a sample of 106 companies was selected by systematic elimination method, which totaled 530 year-company. In this research, linear regression and correlation analysis were used to analyze the hypotheses of the research. To analyze the data and test the hypotheses, Eviews software was used. What can be said in the summing-up and conclusion of the general test of research hypotheses is that there is a speculative bubble in the Tehran Stock Exchange index. In addition, the speculative bubble has an impact on stock returns, and this effect has been confirmed in conditions of market boom and downswing. The results obtained in this study are consistent with the documents referred to in the theoretical framework of the research and financial literature

A binary particle swarm optimization algorithm for ship routing and scheduling of liquefied natural gas transportation

With the increasing global demands for energy, fuel supply management is a challenging task of today’s industries in order to decrease the cost of energy and diminish its adverse environmental impacts. To have a more environmentally friendly fuel supply network, Liquefied Natural Gas (LNG) is suggested as one of the best choices for manufacturers. As the consumption rate of LNG is increasing dramatically in the world, many companies try to carry this product all around the world by themselves or outsource it to third-party companies. However, the challenge is that the transportation of LNG requires specific vessels and there are many clauses in related LNG transportation contracts which may reduce the revenue of these companies, it seems essential to find the best option for them. The aim of this paper is to propose a meta-heuristic Binary Particle Swarm Optimization (BPSO) algorithm to come with an optimized solution for ship routing and scheduling of LNG transportation. The application demonstrates what sellers need to do to reduce their costs and increase their profits by considering or removing some obligations