On-Line Monitoring of Biofilm Accumulation on Graphite-Polypropylene Electrode Material Using a Heat Transfer Sensor.

Andreas Netsch,Michael Wagner,Harald Horn

doi:10.3390/bios12010018

Abstract

Biofilms growing on electrodes are the heart piece of bioelectrochemical systems (BES). Moreover, the biofilm morphology is key for the efficient performance of BES and must be monitored and controlled for a stable operation. For the industrial use of BES (i.e., microbial fuel cells for energy production), monitoring of the biofilm accumulation directly on the electrodes during operation is desirable. In this study a commercially available on-line heat transfer biofilm sensor is applied to a graphite-polypropylene (C-PP) pipe and compared to its standard version where the sensor is applied to a stainless-steel pipe. The aim was to investigate the transferability of the sensor to a carbonaceous material (C-PP), that are preferably used as electrode materials for bioelectrochemical systems, thereby enabling biofilm monitoring directly on the electrode surface. The sensor signal was correlated to the gravimetrically determined biofilm thickness in order to identify the sensitivity of the sensor for the detection and quantification of biofilm on both materials. Results confirmed the transferability of the sensor to the C-PP material, despite the sensor sensitivity being decreased by a factor of approx. 5 compared to the default biofilm sensor applied to a stainless-steel pipe.

Highlights

Two of the major drawbacks generally reported by Janknecht und Melo [13] are the low sensitivity of heat transfer sensors due to high uncertainties of the measurement of the wall temperature and the inability to distinguish between the compounds of the deposits, can be seen by the results reported in this study
The aim of this study was to investigate the applicability of the DEPOSENS biofilm sensor on a graphite-polypropylene (C-PP) material in comparison to the standard stainlesssteel (SST) pipe application, as a direct monitoring device of biofilms developing on the electrode of bioelectrochemical systems (BES) made from the same conductive composite material
The DEPOSENS biofilm sensor is able to identify an accumulation of biofilm on the inside of the pipe on both stainless steel and composite graphite-polypropylene (C-PP) corresponding to the thickness of the accumulated biofilm

Summary

Introduction

Biofilms are used in a variety of technical systems in a beneficial or productive manner, cleaning water in the wastewater treatment over a wide range from membrane bioreactors (MBRs) [1] to trickling filters [2]. Among these technologies in wastewater treatment are bio-electrochemical systems such as microbial fuel cells as new source of energy from wastewater [3] or microbial electrosynthesis cells for the production of base chemicals [4].

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Conclusion