Układy bioelektrochemiczne – nowa generacja bioreaktorów oraz dane, które generują [Bioelectrochemical systems – a new generation of bioreactors with lots of data to handle] Grzegorz Pasternak (Laboratory of Microbial Electrochemical Systems, Faculty of Chemistry, PWr, Wrocław) Bioelectrochemical systems (BESs) - this term refers to any device that can interact with electrons. In particular, this group consists of microbial fuel cells (MFCs), where microorganisms can produce electricity by consuming organic waste, leading to improved environmental depollution. However, the design, operation and data evaluation of MFCs is full of challenges due to the complexity of the system, where microorganisms interact with inert and functional elements such as electrodes, membranes and electrolytes. These devices are typically continuously monitored for various performance parameters and behaviors, resulting in large data sets that require different approaches to perform meaningful analysis. In this talk I will present some examples and a possible challenge related to the application of these systems as biosensors for on-line water monitoring.