Co-culture of bacteria and microalgae for treatment of high concentration biogas slurry

Abstract

The co-culture of microalgae and specific bacteria is conducive for improving wastewater treatment efficiency. In this study, native bacterial strains isolated from pig biogas slurry were screened for effective biogas slurry treatment when co-cultured with different microalgae. Scenedesmus obliquus and Bacillus megaterium (So-B) co-culture was found more efficient in treating high concentration biogas slurry compared with the pure microalgae culture. When the C/N/P ratio in biogas slurry was 106/16/1 and the initial microalgae-bacteria inoculation ratio was 9:1, the co-culture attained the maximum chemical oxygen demand (COD), total phosphorus (TP) and ammonia nitrogen (NH4+-N) removal rates of 85.98 %, 81.03 % and 65.48 %, respectively. High C/N ratio was favorable for NH4+-N removal by the co-culture. In addition, co-culture with bacteria markedly increased the ratio of saturated/unsaturated fatty acids in microalgae. These results suggest that the co-culture could efficiently reduce various nutrients in biogas slurry and simultaneously accumulate biomass with higher biofuel characteristics.