“MFC4Sludge” is a research project that aims to develop an innovative solution consisting of a microbial fuel cell (MFC) coupled to a hydrolytic-acidogenic anaerobic digestion (HA-AD) to treat sewage sludge from wastewater treatment plants (WWTPs). The technologies developed herein will not only improve existing sludge treatments in environmental terms (even avoiding sludge disposal) but also in cost-effectiveness terms (generating electricity in the MFC in order to power the sludge treatment). The objective is to develop a reliable, cost-effective and efficient alternative to existing wastewater sludge treatments with minimum environmental impacts and without increasing energy consumption of current wastewater treatment plants. To that end, “MFC4Sludge” will take advantage of the potentials of MFC regarding direct conversion of sludge into electricity while operating at ambient temperature with low biomass production and neither requiring gas handling nor aeration. Taking into account the latest state-of-the-art, research activities will be focused in: wastewater sludge pre-treatment using partial anaerobic digestion; MFC system development aimed at improving system efficiency and cost-effectiveness; MFC control strategies design in order to reach an optimal performance; and integration of the different elements which compose the final solution.
The economic opportunity of “MFC4Sludge” main goal, which is a process potentially able to degrade more than 90% of the COD with positive energy balance, is a well-supported fact. Indeed, according to latest economic reports, the global market for wastewater treatment delivery equipment, instrumentation, process equipment, and treatment chemicals will increase at a 10,4% compound annual growth rate (CAGR) in the following years. According to this, a vast niche of market is open for wastewater and sludge from wastewater technologies.
- Mathematical modeling: Nonlinear, grey-box mathematical models of HA-AD and MFC processes, combining first-principle physics with empirical data, are developed. On one hand, a detailed model of the HA-AD process is performed in order to reveal non-linear behaviours of the system and to quantify the performance of alternative operational setups. On the other hand, MFC performance is mathematically described by the main electrochemical laws and principles governing its performance losses. In order to assess the quality of the simulations, uncertainty analysis using Monte Carlo methods is also done. Additionally, a sensitivity analysis is conducted in order to deepen the understanding of the processes, and to find the parameters best suited for calibration.
- Distributed Control System (DCS) architecture design and implementation: Development and implementation of the HA-AD-MFC plant DCS architecture, which is composed of two main control layers: upper or supervisory control and lower or real-time controllers. Supervisory control layer runs a Model Predictive Control (MPC) implementation, while lower controllers rely on HA-AD and MFC embedded hardware.
- Hardware and software selection: Selection of the best suited hardware and software, including the study and selection of best sensors for monitoring (pH, temperature, alkalinity, VFA and COD among others) and actuators for dynamic real time feedback control. To that end, a cost-effectiveness analysis is conducted in order to maintain costs as low as possible while achieving DCS expected performance.
- MPC design: Dynamic models are used to predict future HA-AD-MFC process behavior by minimizing the difference between the predicted process response and the desired response while explicitly considering for process constraints. To that end, multi-objective functions are considered, mainly accounting for sludge degradation and VFA concentrations as for HA-AD process, biodegradable substrate concentration, power density and cell potential as for the MFC, and overall mass and energy adjustment as for the integrated process.
- Integration of energy systems: Design of the combined HA-AD-MFC lab scale device and the interfaces to follow the principle of lowest energy demand of the whole system, so as the energy demand of the lab scale device is covered exclusively by a fractional part of the electricity produced in the MFC. Additionally options for covering the energy demand by other renewable resources (e. g. passive solar heating of the AD bioreactor) is also considered with respect to a full scale plant.
- Prototype design, contruction and operation: Process Flow Diagrams (PFDs) and Piping and Instrumentation Diagrams (P&Is) are produced in order to make the construction stage easier. 2D and 3D design are produced as well by using computer aided design software (AUTOCAD and CATIA).
The research leading to these results has received funding from the European Union’s Seventh Framework Programme managed by REA – Research Executive Agency (FP7/2007-2013) under Grant Agreement N.605893.
- Date 29 September, 2013
- Tags Biotechnology, Control Engineering, Energy, Environment, Modeling and Simulation, Multidisciplinary Design Optimization, Public - EU FP7 / H2020
- Programme FP7 Capacities
- Call ID FP7-SME-2013
- Partners ECOTREND (Coord.); EMEFCY; ACONTROL; FRAUNHOFER IGB; LEITAT; AGUAS DE GUIPUZKOA; IDENER
- Project cost 1.495.036 EUR
- Start date August, 2013
- End date July, 2015