Bacherlorprojekt/Masterprojekt: The effects of cell concentrations and electrochemical impedance measurements on biofilm growth

Cell growth

Currently in wastewater treatment plants, high energy consumption is required for the removal of the organic compounds while, most of the times, the energy stored in the chemical bonds of such organic compounds is left unused. Only part of this energy is sometimes recovered in the form of methane-rich biogas through an anaerobic digestion process. In this context, novel bioelectrochemical technologies are emerging, such as microbial electrolysis cells. This device can harness the energy contained in the organic matter of wastewater streams, using exoelectrogenic bacteria, to produce valuable compounds such as hydrogen, thereby removing organic matter. Geobacter sulfurreducens as one of the model exoelectrogenic organism is a subject of great interest in recent years due to its potential to be implemented in different bioelectrochemical devices. Even so, there are still questions that should be addressed about the behavior of this bacteria, such as those that will be investigated in this project.

The proposed project seeks to identify the influence of the inoculation cell concentration on the growth of Geobacter sulfurreducens biofilms. Similarly, it is the objective of this project to clarify the role that electrochemical impedance, a powerful technique to study the evolution of biofilms, plays during this crucial stage in the formation of the biofilm. For that, small bioelectrochemical reactors will be prepared and inoculated at different optical densities with Geobacter sulfurreducens. Additionally, a battery glass reactor with six electrodes will be assemble, applying simple chronoamperometry measurements in three of them, while in the other three such procedure will be interrupted to perform electrochemical impedance spectroscopy. The control of the experiments will require the measurement of pH, optical density at 600 nm, Chemical Oxygen Demand (COD), organic acids concentration and conductivity, while the exact organic acids composition will be determined via High Performance Liquid Chromatography (HPLC). Furthermore, the quality of the biofilms will be evaluated by fluorescence microscopy and qPCR. Therefore, we are looking for a highly motivated students who are willing to work in the field of bioelectrochemistry and contribute in the development of bioelectrochemical systems. Candidates with background in biology and/or chemical or process engineering are preferred.


Beginning from:

October 2022



Period of time:

6 months


Prof. Dr.-Ing. habil. Sven Kerzenmacher – kerzenmacherprotect me ?!uni-bremenprotect me ?!.de

Dr. Óscar Santiago Carretero –

M.Sc. Pavaris Viwatthanasittiphong – pavarisprotect me ?!uni-bremenprotect me ?!.de