The effect of initial inoculation amount of microalgae on synergistic purification of biogas slurry.

In this study, and were inoculated in biogas slurry medium with initial inoculum (OD) of 0.05, 0.1, 0.2, and 0.3, respectively, and 5% CO was continuously injected. The study aimed to examine the carbon sequestration capacity of and , as well as the effectiveness of removing pollutants such as TN, TP, and COD in biogas slurry medium. Additionally, an economic efficiency analysis of energy consumption was conducted. The group with an initial inoculum (OD) of 0.3 for both types of microalgae exhibited better tolerance to pollutants, entered the logarithmic growth stage earlier, promoted nutrient removal, achieved higher energy efficiency, and reduced carbon emissions compared to the other groups. The highest carbon sequestration rates were 18.03% for and 11.05% for . Furthermore, demonstrated corresponding nutrient removal efficiencies of 83.03% for TN, 99.84% for TP, and 90.06% for COD, while exhibited removal efficiencies of 66.35% for TN, 98.74% for TP, and 77.71% for COD. The highest energy efficiency for pollutants and CO removal rates for were 49.51 ± 2.20 and 9.91 ± 0.44 USD, respectively. In conclusion, the findings demonstrate the feasibility of using microalgae for simultaneous purification of biogas and biogas slurry. In this study, and were inoculated in biogas slurry medium with initial inoculum (OD680) of 0.05, 0.1, 0.2, and 0.3, respectively, and 5% CO was continuously injected. The study aimed to examine the carbon sequestration capacity of and , as well as the effectiveness of removing pollutants such as TN, TP, and COD in biogas slurry medium. Additionally, an economic efficiency analysis of energy consumption was conducted. The group with an initial inoculum (OD680) of 0.3 for both types of microalgae exhibited better tolerance to pollutants, entered the logarithmic growth stage earlier, promoted nutrient removal, achieved higher energy efficiency, and reduced carbon emissions compared to the other groups. The highest carbon sequestration rates were 18.03% for and 11.05% for . Furthermore, demonstrated corresponding nutrient removal efficiencies of 83.03% for TN, 99.84% for TP, and 90.06% for COD, while exhibited removal efficiencies of 66.35% for TN, 98.74% for TP, and 77.71% for COD. The highest energy efficiency for pollutants and CO removal rates for were 49.51 ± 2.20 and 9.91 ± 0.44 USD, respectively. In conclusion, the findings demonstrate the feasibility of using microalgae for simultaneous purification of biogas and biogas slurry.