Response surface optimization of microalgae microbial fuel cell (MMFC) enhanced by yeast immobilization for bioelectricity production

In this work, suspended and immobilized Saccharomyces cerevisiae yeast in alginate was utilized as a biocatalyst to interact with different concentrations of tofu wastewater for microalgae microbial fuel cell (MMFC) application. Operating conditions are one of the factors that impact the MMFC's performance, thus they must be optimized. The response surface approach was used to optimize operating conditions, which involved CCDrandomized by five levels of two variables. With an average voltage of 0.13 V, power density of 13.94 mW center dot m(-2), and current density of 102.20 mA center dot m(-2), bioelectricity output produced more suspended yeast than immobilized yeast. The average voltage of MMFC with immobilized yeast was 0.123 V, the power density was 11.25 mW center dot m(-2), and the current density was 91.82 mA center dot m(-2). Immobilized yeast, on the other hand, led in faster stabilization of the resulted electrical output. When compared to suspension yeast, immobilized yeast removed more COD. The best conditions were reached with a yeast concentration of 10.89% w/v and a wastewater concentration of 56.94%, resulting in a power density and COD removal of 11.25 mW center dot m(-2) and 31.82%, respectively. The effect of yeast and wastewater concentrations on power density and COD removal revealed that the model was well supported by experimental results.

Automated summary

In this study, suspended and immobilized Saccharomyces cerevisiae yeast in alginate were used as a biocatalyst to optimize the operating conditions of microalgae microbial fuel cell (MMFC) with different concentrations of tofu wastewater. The results showed that immobilized yeast performed better in producing stable electrical output and removing COD compared to suspended yeast. Therefore, the model using immobilized yeast at a concentration of 10.89% w/v and wastewater concentration of 56.94% achieved the best power density and COD removal efficiency.