SEFCUMPAQ · A NOVEL BIOPROCESS COUPLING WASTEWATER TREATMENT WITH ELECTRICITY PRODUCTION TO REMEDIATE METAL POLLUTED AQUATIC ENVIRONMENTS

A novel bioprocess coupling wastewater treatment with electricity production to remediate metal polluted aquatic environments

Contamination of the aquatic environment has become a major concern worldwide. For a strong European Research Area (ERA) it is necessary to develop technologies dealing with pollution control as well as bioenergy production. This will allow ERA to stay competitive with the rest of the world, which is investing massively in this area. Therefore, there is a demand in Europe to improve the knowledge in energy technology dealing with pollution control. To accomplish this goal, this research proposal was designed as such that it contains both fundamental and applied aspects. The critical research and development problems relate to the mechanisms involved and the enhancement of biofilm formation on the electrode for the bioconversion to the electricity production and process operation (to enhance the electricity production). This will provide a tool for the better understanding of the mechanism involved and thus lead to a sediment fuel cell (SFC) with constant power output that can be installed in natural wastewater treatment systems. The key aspects of this proposal addressed by means of novel and inter-disciplinary research training are mentioned below. More specific, applied electron transfer has become a very timely, relevant and strategic field of bioscience and technology all over the world. The enhancement of competence and skill diversification of the beneficiary, the present proposal's aim, had been progressively achieved through three main steps: 1. establishment of complementary interdisciplinary expertise at an advanced level in the field of bioenergy and development of different bioelectrochemical cell configurations 2. better understanding of mechanisms involved in electron transfer in electroactive biofilms of pure as well as mixed microbial communities for practical applications 3. electrode surface engineering for enhanced power production aiming at practical applications. In the first step (months one to six), Dr Kumar had been introduced to the detailed aspects of the underlying engineering and the scientific challenges related to bioenergy technology, such as electron transfer and electroactive biofilms. In addition, an extensive literature review covering the key aspects of already existing science and technologies employed for bioenergy production has been carried out and a manuscript will be communicated to a leading Journal entitled 'Engineering microbial processes from natural Environments: A path for waste processing and bioenergy production'. In the second step (months 6 to 12), Dr Kumar learned various electrochemical techniques, which are nowadays considered to be the state-of-the-art methodologies to retrieve the intrinsic redox-active proteins, electron transfer, which is of crucial interest for understanding the involved mechanisms. In details, he investigated how the anode potential affected the microbial diversity of the electroactive biofilm community. Electroactive biofilms were induced to grow on graphite rod electrodes in the presence of acetate as electron donor. In this study he used two different configurations (single and dual chambered cell) of microbial electrolysis cells containing graphite electrodes (two in each cell) and each cell at a different anode potential, with Eanode = -0.2, -0.3, 0.0 and +0.2 V versus silver chloride (AgCl). Anaerobic sludge as inoculum, acetate as the substrate and batch and continuous-flow operation were used. Increased anodic currents for bioelectrocatalytic oxidation of acetate were obtained when the electrodes are incubated for longer periods with continuous electron donor feeding. Among single chambered bioelectrochemical cells, the electrochemical cell posed at the highest potentials produced the highest current densities, reaching up to 6000 mA/m2 at the saturation of an amperometric curve, the electrode at the lowest potential produced a maximum of 1500 mA/m2. However, among the dual chambered bioelectrochemical cells, the electrochemical cells poised at -0.3 and -0.2 V potentials showed higher current densities (4000 and 6000 mA/m2, respectively) than anodes poised at higher potentials (2000 mA/m2 for +0.2 V) at the cyclic voltammetric curve. During the last part of the project (months 12 to 24) Dr Kumar visited Dr Leech's research group at the National University of Ireland, Galway, Ireland and devoted his efforts to the design of bioelectrochemical cell configurations for better understanding of electron flow in biofilms for bioenergy applications. The study on geobactor sulfuredence provided novel results on the anode influence on power density in dual and single bioelectrochemical cells and outcomes of this study is planned to be communicated in a visible scientific journal. In details, geobactor sulfurreducens biofilm growth induced a bioelectrocatalytic response to acetate oxidation at different potentials (Eanode = +0.4, +0.2, 0.0 and -0.2 V versus AgCl), with current densities of acetate scaling with the applied potential in single electrochemical cells. In contrast, biofilms of dual chambered bioelectrochemical cells show higher current densities at lower potential. In addition, an invited minireview discussing hints for improving the existing research concerning electron transfer and electroactive biofilms is being drafted for the Biochemical Society Transactions journal. In addition, Dr Kumar investigated potential of surface-functionalised/engineered electrodes in electrochemical cells using unmodified; carboxylic acid (COOH) modified; amine (NH2) modified; and ethyl group (C2H5) modified electrodes. In short, NH2 modified study showed higher current densities and kinetics than others and has a great prospect for biofuel application. As a result of this novel research project, Dr Kumar gained a solid understanding of state-of-the-art electrochemical techniques (cyclic voltammetry, amperometry and linear sweep) in particular the technological challenges related to electron transfer issues. In addition, he acquired the necessary familiarity with this and related aspects, such as research, management and time management skills, as well as negotiation strategies. Concerning data analysis methodologies, Dr Kumar acquired the necessary knowledge of advanced methodologies utilised for electroactive biofilms and microbial community analysis of the electroactive biofilms, which is nowadays considered to be the state-of-the-art methodology. In terms of scientific and technologically relevant achievement, the main result was influence of anode potential on electron transfer, through the comparison with pure and mixed consortia and enhancing the current generation by surface tailored electrode surfaces. The enhancement of competence and skill diversification, encompassing fundamental science and applied technology aspects, acquired by the beneficiary during this research training and career development program decisively supported Dr Kumar with the award of a follow up research project, a Marie Curie international outgoing fellowship (MC-IOF). This is as a part of a structured and long-term professional development plan. The added knowledge gives Dr Kumar the ability to quickly assess the technological impact and value of a research topic and will put him into an excellent position to build an entirely new research program in the field of bioenergy science and technology. This would provide with a high potential of generating technology transfer (e.g. technological spin-offs) in relationship with European industry, which can substantially contribute to European excellence and competitiveness in the field of bioenergy and pollution control. Additionally, the key knowledge was transferred to the host institution by several activities and he also participated in achieving a successful Seventh Framework Programme (FP7) People 2010 International Research Staff Exchange Scheme (IRSES) project 'BioWET', thus enables to consolidate world-leading expertise in this research field within one European Union (EU) based institution. This may allow for commercial joint ventures or spin offs based upon new products. Such a development would provide a direct economic benefit and return to the EU and highlights the crucial role that EU administered research investments play.

Data: CORDIS, © European Union