Growth of Desmodesmus subspicatus green microalgae and nutrient removal from sugarcane vinasse clarified by electrocoagulation using aluminum or iron electrodes

Abstract

Sugarcane ethanol production generates considerable quantities of vinasse, its main wastewater. Microalgae cultivation is a promising option for effluent remediation, since the generated biomass can be feedstock for biofuel and bio-based chemical production. Due to vinasse high turbidity, pretreatment is necessary to clarify this effluent, adapting it as a mixotrophic culture medium. In this context, the present research evaluated the integrated process of electrocoagulation (EC) of sugarcane vinasse with aluminum or iron electrodes and subsequent cultivation of green microalgae Desmodesmus subspicatus. Results indicate pH neutralization and high turbidity removal efficiency by EC with both electrode materials. Aluminum EC and subsequent microalgae cultivation removed 66 and 75% of initial total organic carbon and total nitrogen, respectively, with biomass productivity of 1.45 g L-1day-1 and maximum specific growth rate of 0.095 h-1. Microalgae productivity was inferior in vinasse pretreated by iron EC, suggesting possible interference of ferric compounds in the microalgal development.

Keywords

• distillery effluent
• mixotrophic growth
• wastewater treatment