Toward complete and sustainable biogas valorization: Ectoine synthesis using a methanotroph-microalgae consortium

Abstract

To improve the economic viability and sustainability of anaerobic digestion plants, alternative biogas valorization routes are increasingly being sought. One promising strategy involves biosynthesizing high-value products, such as ectoine, from biogas, given their high market value and diverse industrial applications. This study presents the first techno-economic assessment and environmental impact evaluation of a newly established ectoine production pathway, which uses a consortium of methanotrophs and microalgae (methalgae) to simultaneously valorize both the CH4 and COQ fractions of biogas. The techno-economic assessment showed that this process can achieve ectoine production costs of <euro>186 kg-1 , with best-and worst-case scenario costs ranging from <euro>115 to <euro>342 kg-1 . This represents an average cost reduction of 39 % compared to traditional ectoine production routes, namely bacterial milking and methanotroph-only processes. Cost sensitivity analyses identified production scale and ectoine yield as the most influential economic drivers. The environmental impact assessment showed that the methalgae-based process can achieve important greenhouse gas emissions and water use reductions, reaching an average of 36 % and 22 %, respectively, compared to conventional ectoine production approaches. These findings demonstrate the potential of methalgae-based processes as economically attractive and environmentally sustainable alternatives for producing high-value products from biogas.