Effect of unconventional pretreatments on the morphology and biochemical methane potential of Sargassum spp.

Abstract

Sargassum spp. blooms disrupt Caribbean coastal ecology, economy, and community health. Methane production is a promising solution for valorizing this macroalgae and cutting macroalgae management costs. However, pretreatment is essential to address low efficiency due to the presence of lignocellulose and calcite in the biomass morphology. In this work we evaluate the effects of non-chemically driven pretreatments (i.e. microwave, sonication, and water wash at 40 °C) on the morphology and biochemical methane potential (BMP) of the Sargassum spp. biomass. The morphological properties of the biomass were determined using X-ray diffractometry (XRD), FT-IR, SEM. The BMP was evaluated using an automated potential test system (AMPTS® II). The yield of the untreated biomass was equal to 72.25 NmL/g VS. The microwave pre-treatment induced a 26.06 % reduction in yield, primarily due to the formation of recalcitrant components. Sonication pretreatment led to a 5.28 % increase in yield, attributed to the cellular-level alterations prompted by cavitation phenomena. In contrast, the water wash pretreatment demonstrated a significant yield enhancement of 20.76 % compared to untreated biomass. However, all the investigated scenarios are not able to generate a positive income by solely selling the obtained electricity.