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Enhancing hyper-thermophilic hydrolysis pre-treatment of chicken manure for biogas production by in-situ gas phase ammonia stripping

Yin, Dong-Min, Qiao, Wei, Negri, Camilla, Adani, Fabrizio, Fan, Run, Dong, Ren-Jie
Bioresource technology 2019 v.287 pp. 121470
ammonia, ammonium nitrogen, anaerobic digestion, bacteria, gas production (biological), gases, hydrolysis, methane production, methanogens, poultry manure
Hydrolysis is normally the rate limiting step for anaerobic digestion (AD). In this study, hyper-thermophilic (70 °C) pre-treatment of chicken manure under HRTs of 10, 5, 3, 2 and 1 d(s) was investigated to enhance the hydrolysis efficiency for biogas production. In-situ phase gas stripping was integrated into the pre-treatment reactor to remove ammonia-N and to enhance the hydrolysis performance. The results showed that in-situ gas stripping removed 18%–31% of ammonia-N and improved hydrolysis by 2.6%–31.1%. The methane yield of pre-hydrolyzed chicken manure reached 518 mL g-VS−1 under optimal HRT 3 days, which was 54.6% higher than that obtained from the control reactor. However, shortening HRTs below 3 days resulted in a significant reduction in hydrolysis efficiency. The percent of hydrolysis and acidogenesis bacteria reduced to 40.6% at HRT 1 d. 16sRNA results indicated existence of methanogens in pre-hydrolysis reactor. Further optimizing of ammonia stripping was thus needed for hydrolysis pre-treatment.