Ectoine Production from Biogas in Waste Treatment Facilities: A Techno-Economic and Sensitivity Analysis.

The capacity of haloalkaliphilic methanotrophic bacteria to synthesize ectoine from CH 4 -biogas represents an opportunity for waste treatment plants to improve their economic revenues and align their processes to the incoming circular economy directives. A techno-economic and sensitivity analysis for the bioconversion of biogas into 10 t ectoine·y -1 was conducted in two stages: (I) bioconversion of CH 4 into ectoine in a bubble column bioreactor and (II) ectoine purification via ion exchange chromatography. The techno-economic analysis showed high investment (4.2 M€) and operational costs (1.4 M€·y -1 ). However, the high margin between the ectoine market value (600-1000 €·kg -1 ) and the estimated ectoine production costs (214 €·kg -1 ) resulted in a high profitability for the process, with a net present value evaluated at 20 years (NPV 20 ) of 33.6 M€. The cost sensitivity analysis conducted revealed a great influence of equipment and consumable costs on the ectoine production costs. In contrast to alternative biogas valorization into heat and electricity or into low added-value bioproducts, biogas bioconversion into ectoine exhibited high robustness toward changes in energy, water, transportation, and labor costs. The worst- and best-case scenarios evaluated showed ectoine break-even prices ranging from 158 to 275 €·kg -1 , ∼3-6 times lower than the current industrial ectoine market value.