Electrogenic and biomass production capabilities of a Microalgae–Microbial fuel cell (MMFC) system using tapioca wastewater and Spirulina platensis for COD reduction

ABSTRACT

Tapioca is a starch extracted from cassava and is one of the most important products of the secondary food industry in developing countries such as Indonesia. However, the processing of cassava to extract tapioca generates nutrient-rich wastewater. In this paper, the bioelectricity and biomass production from microalgae Spirulina platensis within a hybrid Microalgae-Microbial fuel cell to reduce the chemical oxygen demand in wastewater from home-made tapioca industry is investigated. Native microbes in tapioca wastewater are used as inoculum in the anode chamber to generate electrons, while Spirulina culture in cathode chamber produces oxygen for the Oxygen Reduction Reaction. Cheap graphite rods, singlet or doubled, are used as electrodes and the influence of dark/light period is also studied. The experimental results show that the device generates electricity up to 14.47 ± 0.7 mW·m⁻² when doubled graphite rods are adopted, the membrane surface area is 2.85 cm², and dark/light cycle is 0:24. The chemical oxygen demand removal is 67% in this configuration, while the average productivity of Spirulina is approximately 55.38 ± 6.39 mg·L⁻¹·day⁻¹, with average growth rate constant of 0.172 ± 0.015 day⁻¹. The proposed systems for tapioca wastewater treatment provides an encouraging way to reduce treatment costs, to generate renewable bioelectricity and to produce useful microalgae biomass.

KEYWORDS:

• Biomass production
• COD removal
• electricity generation
• microbial fuel cell
• tapioca wastewater

Acknowledgments

Authors would like to thank the Center of Biomass and Renewable Energy (C-BIORE) – Diponegoro University for guidance and research facilities.

Conflicts of Interest

The Authors declare that they do not have any conflicts of interest.

Additional information

Funding

Carlito da Costa was supported by Fundacao Asswa’in Timor Lorosa’e (FUNATIL) through the Universidade Oriental Timor Lorosa’e (UNITAL) – East Timor.

Notes on contributors

H. Hadiyanto

Prof. H. Hadiyanto is a Professor at Diponegoro University who has expertise in biomass, bioenergy, environmental science and technology. He finished his doctorate at Wageningen University, the Netherlands. Moreover, now he manages the Center of Biomass and Renewable Energy (C-BIORE), one of a big research center in Diponegoro University.

Marcelinus Christwardana

Marcelinus Christwardana PhD, is a junior lecturer and Assistant Professor at Institut Teknologi Indonesia who has expertise in biomass and bioenergy especially microbial and enzymatic biofuel cell. He finished his doctorate at Seoul National University of Science and Technology, South Korea.

Carlito da Costa

Carlito da Costawas a Master Student of Chemical Engineering at Diponegoro University. Currently, he is Assistant Professor of Environmental Engineering at Oriental University Timor Lorosa'e (UNITAL), Dili - East Timor.