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A parametric stirring optimization framework was established using computational fluid dynamics (CFD) simulations to systematically investigate the effects and mechanisms of mechanical-pneumatic synergistic stirring on the mixing and mass transfer characteristics of high-solid anaerobic digesters. This framework integrated a power-law model to describe the rheological behavior of the material, a multiphase flow model, and quantitative optimization criteria. Utilizing a typical high-solid concentration (TS=15%) as a specific case, single-phase and multiphase numerical models were developed to quantitatively evaluate the flow field distribution under four types of impellers (double-pitched blade turbine, disk turbine, anchor, and single helical ribbon) and three rotational speeds (20.00, 60.00, and 100.00r/min). The results indicated that the dead zone volume was reduced by 81.49% with the single helical ribbon impeller at 60.00r/min, while the average liquid-phase shear stress (4.42Pa) remained below the microbial floc destruction threshold of 5.00Pa. Furthermore, when inclined gas jet stirring was coupled, a nozzle inclination angle of 30° was found to increase the gas holdup to 24.20%, representing a 4.27-fold improvement over vertical jetting. The nozzle orifice diameter was optimized to 10.00mm to achieve synergistic control over the high-speed liquid-phase region ratio and bubble number density. Ultimately, a bottom-symmetric dual-nozzle-single helical ribbon impeller synergistic stirring system was constructed, which increased the mixing uniformity index by 14.75% and reduced energy consumption by 28.95%. Based on the successful application and flow field analysis of the TS=15% system, quantitative criteria for matching microbial activity maintenance with fluid dynamics optimization were established. This parameterized CFD framework can be extended to evaluate mixing effects in systems with varying solid content by incorporating material-specific rheological parameters, providing a universal optimization method and a theoretical foundation for the design of high-solid anaerobic digestion reactors.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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