title: Influence of fluid dynamics on anaerobic digestion of food waste for biogas production.
abstract: To enhance the stability and efficiency of an anaerobic process, the influences of fluid dynamics on the performance of anaerobic digestion and sludge granulation were investigated using computational fluid dynamics (CFD). Four different propeller speeds (20, 60, 100, 140 r/min) were adopted for anaerobic digestion of food waste in a 30 L continuously stirred tank reactor (CSTR). Experimental results indicated that the methane yield increased with increasing the propeller speed within the experimental range. Results from CFD simulation and sludge granulation showed that the optimum propeller speed for anaerobic digestion was 100 r/min. Lower propeller speed (20 r/min) inhibited mass transfer and resulted in the failure of anaerobic digestion, while higher propeller speed (140 r/min) would lead to higher energy loss and system instability. Under this condition, anaerobic digestion could work effectively with higher efficiency of mass transfer which facilitated sludge granulation and biogas production. The corresponding mean liquid velocity and shear strain rate were 0.082 m/s and 10.48 s-1, respectively. Moreover, compact granular sludge could be formed, with lower energy consumption. CFD was successfully used to study the influence of fluid dynamics on the anaerobic digestion process. The key parameters of the optimum mixing condition for anaerobic digestion of food waste in a 30 L CSTR including liquid velocity and shear strain rate were obtained using CFD, which were of paramount significance for the scale-up of the bioreactor. This study provided a new way for the optimization and scale-up of the anaerobic digestion process in CSTR based on the fluid dynamics analysis.
authors.affiliation: a College of Pharmacy , Hebei North University , Zhangjiakou , People's Republic of China.
authors.forename: Fengping
authors.initials: F
authors.lastname: Wang
authors.affiliation: b School of Food and Biological Engineering , Jiangsu University , Zhenjiang , People's Republic of China.
authors.forename: Cunsheng
authors.initials: C
authors.lastname: Zhang
authors.affiliation: b School of Food and Biological Engineering , Jiangsu University , Zhenjiang , People's Republic of China.|c Key Laboratory of Development and Application of Rural Renewable Energy , Ministry of Agriculture , Chengdu , People's Republic of China.
authors.forename: Shuhao
authors.initials: S
authors.lastname: Huo
mesh_terms: D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D056804:Biofuels / Q000032:analysis*; D005735:Garbage; D057446:Hydrodynamics; D012722:Sewage / Q000032:analysis*
chemical_list: D056804:Biofuels; D012722:Sewage
keywords: Anaerobic digestion; CFD; biogas; fluid dynamics; food waste