Influence of operational conditions on the performance of biogas bioconversion into ectoines in pilot bubble column bioreactors

Abstract

The application of biogas as a low-priced substrate for the production of ectoines constitutes an opportunity to decrease their production costs and to enhance the viability of anaerobic digestion. The influence of operational conditions on CH4-biogas biodegradation and on ectoines production yields was assessed in continuous pilot bubble column bioreactors. The rise in biomass concentration from 1 to 3 g L−1 resulted in a decrease in the specific ectoine content from 42 ± 8 to 30 ± 4 mgectoine gVSS−1. The concentration of Cu2+ and Mg2+ did not impact process performance, while the use of ammonium as N source resulted in low CH4 biodegradation and ectoine yields (13 ± 7 mgectoine gVSS−1). The increase in CH4 content from 4.5 to 9 %v·v−1 enhanced CH4 removal efficiency. Process operation at NaCl concentrations of 3 %w·w−1 instead of 6 %w·w−1 decreased the ectoine yield to 17 mgectoine gVSS−1. Finally, Methylomicrobiumburyatense was identified as the dominant species.