Development of microalgae-bacteria symbiosis system for enhanced treatment of biogas slurry

In this study, microalgae-bacteria consortia were developed using bacteria and microalgae isolated from biogas slurry for enhanced nutrients recovery and promoted microalgae growth in wastewater. The enhancement rate was introduced to quantify the interaction between bacteria and microalgae. Co-culture of the indigenous microalgae and bacteria could significantly improve the tolerance of microorganisms to pollutants, increase value-added products’ production, promote nutrients removal, and reduce carbon emissions compared to mono-culture. The co-culture of Chlorella sp. GZQ001 and Lysinibacillus sp. SJX05 performed best, with its biomass, lipid, protein and fatty acid methyl ester productivities achieved 113.3, 19.2, 40.9 and 3.7 mg·L⁻¹·d⁻¹, respectively. The corresponding nutrients removal efficiencies for ammonia nitrogen, total nitrogen, total organic carbon, and total phosphorus were 83.2%, 82.1%, 34.0% and 76.6%, respectively. These results indicated that co-culture of certain indigenous bacteria and microalgae is beneficial to biogas slurry treatment and microalgae growth.