Denitrification of aging biogas slurry from livestock farm by photosynthetic bacteria

Abstract

Huge amount of aging biogas slurry is in urgent need to be treated properly. However, due to high NH₃-N concentration and low C/N ratio, this aging biogas slurry is refractory for traditional methods. Its denitrification has become a big challenge. In this paper, photosynthetic bacteria (PSB) were employed to handle this problem. The results showed denitrification of aging biogas slurry by PSB treatment was promising. The highest removal efficiency of NH₃-N reached 99.75%, much higher than all other treatments. The removal of NH₃-N followed pseudo zero order reaction under dark-aerobic condition. The better inoculation rate for NH₃-N removal was 30%; and aerobic condition was more beneficial for NH₃-N removal than anaerobic condition because of different metabolic pathways.

Keywords: Aging biogas slurry; Denitrification; Photosynthetic bacteria; Process factor.