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

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 center dot m(-2) when doubled graphite rods are adopted, the membrane surface area is 2.85 cm(2), 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 center dot L-1 center dot 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.

Automated summary

This paper investigates the use of a hybrid Microalgae-Microbial fuel cell to treat wastewater from home-made tapioca industry. The system utilizes native microbes in the wastewater to generate electricity while also producing biomass using microalgae. The results show promising potential for reducing treatment costs, generating renewable bioelectricity, and producing useful microalgae biomass.