Evaluation of the effect of a static magnetic field on a microalgae-bacteria consortium and its application on wastewater treatment

Abstract

Microalgae in consortia with bacteria are considered a viable option for developing biorefineries due to their potential to obtain biomass of high industrial value and remove wastewater contaminants. However, this technological process is associated with high production costs and low biomass productivity, which can be remedied using alternative technologies such as applying the static magnetic field (SMF). Therefore, the general objective of the research was to evaluate the effects of the application of an SMF on the growth and metabolism parameters of a Chlorella microalgae-bacteria consortium for use in wastewater treatment. The effect of an SMF of 47 mT on the growth parameters, metabolism, and photosynthetic capacity of microorganisms grown in synthetic media and piggery wastewater was investigated. Furthermore, the influence of SMF on the chemicalphysical characteristics of piggery wastewater treated with the microalgaebacteria consortium was evaluated. The SMF increased the growth parameters of the consortium, being more efficient when applied during the early exponential phase of growth. Moreover, SMF increased the quantum yield for electron transport and the number of active reaction centers in the microalgae cells, suggesting the formation of radical pairs P680.+ and Phe.- as a possible cause of the increase in the photosynthetic efficiency of microalgae. On the other hand, the improvement of the growth parameters of the consortium cultivated in piggery wastewater was associated with the increase in the quantum yield of photosystem II of the microalgae and the possible influence of the SMF on the bacterial community, which as a whole increased the efficiency of the chemical-physical and biological processes of nutrient removal from the liquid medium.