Microbial fuel cell for wastewater treatment : heavy metal removal, sewage sludge treatment, and its potential application in wastewater reuse in irrigation

While water scarcity and energy demand are continuously increasing in the world, alternative sources are needed to meet the requirement of a growing population. Microbial Fuel Cell (MFC) is a sustainable technology that converts organic matter in wastewater into electricity, thus it can be a potential alternative source for water and energy. Although significant advances in MFC research have been accomplished in the last few years, improvement in power generation and decrease in material cost are still necessary to bring MFC into practical application. The main goal of this work is to contribute in making MFC more applicable in industrial and municipal facilities, and to evaluate its scaling up for real world application. First, heavy metal removal by MFC was studied. Simultaneous high power generation (3.6 W/m²) and high Cd (90%) and Zn (97%) removal efficiencies were achieved in a single chamber air-cathode microbial fuel cell (MFC). The maximum tolerable concentrations (MTCs) that did not affect power output were 200 μM for Cd and 400 μM for Zn. Gradual increase of metals concentrations lead to much slower reduction in voltage output. Biosorption and sulfides precipitation are the major mechanisms for the heavy metal removal in the MFCs. This study expanded MFC application for the treatment of industrial waste streams containing both organic matter and heavy metals. Then, enhancement of sewage treatment by MFC was investigated. Although energy costs required for wastewater treatment are offset by methane production from sewage sludge treatment, not all the energy is extracted from sludge and effluents need additional treatment, such as aeration, to meet environmental regulations. MFC has been used to convert organic matter in sludge into electricity. However, improvement of power production is still needed. We studied the effect of fermentation pre-treatment and a novel design cloth-electrode assembly microbial fuel cell (CEA-MFC) on electricity production from sewage sludge. Fermentation pretreatment of sludge effectively increased the soluble organic matter and improved the reactor performance. The optimum fermentation time was 96 hours and resulted in maximum power density of 1200 mW/m², which is 275% higher than those previously reached in MFC systems. Thus, MFCs could be added successfully to existing wastewater treatment infrastructure for more efficient energy conversion. Last, we examined the feasibility of using MFC technology for field application before irrigation. Although wastewater use in irrigation resolves the problem of water shortage, it also presents a threat to the environment. Thus, wastewater treatment before irrigation is needed. MFC has potential to treat wastewater and generate electricity simultaneously while leaving low residual concentrations of nutrients in the effluent. In order to investigate the economic returns from using MFC to treat wastewater before agricultural application, a case study involving food wastewater in a semi-arid region was considered. The various profits from treated water, produced electricity and nutrients in effluent were evaluated. The effluent water quality was compared to environmental regulations. The analysis showed that MFC is a promising technology that can resolve issues of water and energy shortage and thus can ensure food security

Ground water and surface water under stress

Presented at Ground water and surface water under stress: competition, interaction, solutions: a USCID water management conference on October 25-28, 2006 in Boise, Idaho.Includes bibliographical references.Conventional irrigation practices are predicated on maximizing crop yield - a biological objective. As worldwide competition for water intensifies a fundamentally new paradigm for irrigation management is emerging predicated on maximizing net returns to water - an economic objective. Maximizing returns to water generally involves some degree of deficit irrigation, particularly when water supplies or system constraints limit the availability of water, but few farmers are well equipped to deal with the analytical challenges associated with managing water deficits. This paper presents a web based advisory service for irrigation management now in use in a pilot program in Oregon. While the system can be used for conventional irrigation scheduling it is designed explicitly to assist irrigation managers with planning and implementing optimum irrigation strategies when water supplies are limited or expensive. Though originally developed for use in Oregon, discussions with other states have been initiated to make the system available nationally. This paper provides an overview of the analytical framework and demonstrates primary features of the user interface

Energy generation in a Microbial Fuel Cell using anaerobic sludge from a wastewater treatment plant

ABSTRACT In microbial fuel cells (MFCs), the oxidation of organic compounds catalyzed by microorganisms (anode) generates electricity via electron transfer to an external circuit that acts as an electron acceptor (cathode). Microbial fuel cells differ in terms of the microorganisms employed and the nature of the oxidized organic compound. In this study, a consortium of anaerobic microorganisms helped to treat the secondary sludge obtained from a sewage treatment plant. The microorganisms were grown in a 250 mL bioreactor containing a carbon cloth. The reactor was fed with media containing acetate (as the carbon source) for 48 days. Concomitantly, the electrochemical data were measured with the aid of a digital multimeter and data acquisition system. At the beginning of the MFC operation, power density was low, probably due to slow microorganism growth and adhesion. The power density increased from the 15th day of operation, reaching a value of 13.5 μW cm–2 after ca. 24 days of operation, and remained stable until the end of the process. Compared with data in the literature, this power density value is promising; improvements in the MFC design and operation could increase this value even further. The system investigated herein employed excess sludge as a biocatalyst in an MFC. This opens up the possibility of using organic acids and/or carbohydrate-rich effluents to feed MFCs, and thereby provide simultaneous effluent treatment and energy generation

Ajaltoun, Lebanon, residential model for steep slopes

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1984.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCHIncludes bibliographical references.The objective of this thesis is to develop a residential model for steep slopes, in the mountain village of Ajaltoun. It is anticipated that this preliminary design would represent an alternative method for residential development on steep slopes in the context of Lebanon. The study starts with an introduction describing the existing housing conditions that resulted from the continuing civil war and the need to develop steep land, thus justifying the purpose of such a model. The introduction is followed by the project description where the goals and strategies of this preliminary design are stated and the physical layout graphically presented. The project deals only with the design aspects of the circulation and access, the lots subdivision layout, and the dwelling layout.by Toufic Abourached.M.S

Enablers and barriers of constructed wetlands as a nature-based wastewater treatment solution: case studies from 5 countries

This record contains a poster. Presented at the 43rd WEDC International Conference</p

Efficacy of single-chamber microbial fuel cells for removal of cadmium and zinc with simultaneous electricity production

Simultaneous high power generation (3.6 W/m2) and high Cd (90%) and Zn (97%) removal efficiencies were demonstrated in a single chamber air-cathode microbial fuel cell (MFC). The maximum tolerable concentrations (MTCs) were estimated as 200 μM for Cd and 400 μM for Zn. Increasing the concentrations of Cd to 300 μM and Zn to 500 μM resulted in voltage drops by 71 and 74%, respectively. Feeding the MFCs with incrementally increased Cd and Zn concentrations resulted in much slower reduction in voltage output. Biosorption and sulfides precipitation are the major mechanisms for the heavy metal removal in the MFCs.US National Science Foundation (CBET 0955124)