Investigation of optimal conditions for microbial cultivation and its immobilization on microbial fuel cell electrodes

Name: Pruetsaji Winaikij

keyword: Growth rate

LCSH: Microbial fuel cells

; Electrochemical activities

LCSH: Electrochemical analysis

; Immobilization

Abstract: Microbial fuel cell (MFCs) is a biological device that harvests chemical energy from microbial catalytic abilities of organic compounds in wastewater which is then converted to electrical energy. It is known that electrochemically active microorganisms that are effective in electron transfer are also a key factor to the MFC performance. In the study of microbe-electrode immobilization, the microorganisms collected from an up-flow anaerobic sludge blanket at Cho-heng rice vermicelli industry were employed as inoculum. The optimal conditions for microbial cultivation were initially investigated to identify the period of various growth phases (i.e. lag, log, stationary and death phases) under different cultivation temperatures such as 25, 30 and 35°C. The effect of agitation including horizontal and turbulence shaking was also explored. It was found that the microorganisms cultivated at 35°C using a horizontal shaking provided the fastest growth rate as the dry weight of microorganisms went up to 1.82 g/L and reached the log phase within 6 hours. The interactions between microorganisms at various growth phases were studied by cyclic voltammetry (CV). The mechanism of electron transfer in term of direct (DET) or indirect (IDET) electron transfer was also investigated using three electrolyte solutions: microbe-suspended MLB media, microbe-suspended PBS media and the used MLB media without microbe. The results suggested that the main process of electron transfer was the IDET via the endogenous or exogenous mediator. In addition, electrodes of MFCs were studied through the microbe-electrode immobilization processes which were assessed through electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Electrodes used in this present work were stainless steel (SS), granular activated carbon (GAC) and graphite plate. The results of EIS show that the resistance is greatly influenced by the immobilization time of microbes to form the biofilm on the electrode surface, the longer the time the smaller the resistance. The morphology of microorganisms immobilized on electrode surface showed a vast network of electrochemically active bacteria biofilm. For the first time, this work experimentally demonstrated the benefits of biofilm formation on the electrode surface using electrochemical techniques. The electrical connections through a formation of biofilm exhibited an improved electrochemical activity of the microorganisms

Thammasat University. Thammasat University Library

Address: BANGKOK

Email: preserv@tu.ac.th

Name: Paiboon Sreearunothai

Role: advisor

Created: 2016

Modified: 2021-06-01

Issued: 2021-06-01

วิทยานิพนธ์/Thesis

application/pdf

DOI: 10.14457/TU.the.2016.525

eng

DegreeName: Master of Engineering

Level: Master's Degree

Descipline: Engineering Technology

Grantor: Thammasat University

©copyrights Thammasat University

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