Exploring the Bioelectrochemical Characteristics of Activated Sludge Using Cyclic Voltammetry
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Exploring the Bioelectrochemical Characteristics of Activated Sludge Using Cyclic Voltammetry Dena Z. Khater 1 & K. M. El-khatib 1 & Rabeay Y. A. Hassan 2
Received: 9 May 2017 / Accepted: 2 June 2017 # Springer Science+Business Media, LLC 2017
Abstract Due to the potential interest, bioelectrochemical responses of activated sludge using the three-electrode system are tested. From the cyclic voltammograms, the oxidation current output is increasing due to incubation time increase, whereas 5, 25 and 39.33 μA are obtained after 3, 72 and 96 h, respectively. Changing the working electrode from glassy carbon to carbon paste led to the increase in the electrochemical signal from 0.3 to be 3.72 μA. On the other hand, the use of the lipophilic redox mediator (2,6-dichlorophenolindophenol (DCIP)) amplified the oxidation current to reach 19.9 μA instead of 2.1 μA. Based on these findings, the mixed microbial community of the activated sludge is exploited as a catalyst for the biooxidation of the degradable organic substrates, while DCIP is used as a mobile electron carrier from the intracellular matrix of the metabolically active cells to the carbon paste electrode which served as the final electron acceptor. Therefore, the extracellular electron transfer from the formed active biofilm at the electrode surface is assisted by the existence of DCIP. Keywords Microbial fuel cells (MFCs) . Activated sludge . Electroactive biofilm formation . Electron mediator (DCIP)
Introduction In principle, a microbial fuel cell (MFC) is considered as an alternative and simple energy resource [1–4]. It can be used for production of electricity and treatment of water from pollutants[5–9]. Construction of microbial fuel cells requires electroactive microorganisms,
* K. M. El-khatib [email protected]
1
Chemical Engineering & Pilot Plant Department, National Research Centre (NRC), El-Tahrir Street, Dokki, Cairo 12311, Egypt
2
Microanalysis Laboratory, Applied Organic Chemistry Department, National Research Centre (NRC), El-Tahrir Street, Dokki, Cairo 12311, Egypt
Appl Biochem Biotechnol
conductive solid electrodes (anode and cathode material) and suitable biodegradable organic substances [10]. The electrochemical performance of each component of the microbial fuel cells (i.e., electrode materials, electroactivity of the organisms or the biodegradation rate of the utilized organic substrate) is characterized using cyclic voltammetry (CV) [11, 12]. Thus, to develop MFC approach, one of these elements could be the target of the study. The selection of the biocatalyst (i.e., the microbe which oxidizes the complex organic molecules to liberate free electrons) is our concern. Thus, a better understanding of the activated sludge is assigned for this study. Basically, activated sludge is a mixture of a variety of microorganisms, which have high biodegradation activity and high tolerance towards various organic substrates[13–17]. In activated sludge wastewater plants, the oxygenation is essential for biodegradation efficiency purposes[18–20].
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