CFD Simulation on Hydrodynamic Behaviors of Anaerobic Granule Swarms

Abstract

An internal circulation (IC) anaerobic reactor is widely used in the treatment of municipal and industrial wastewater with high volumetric loading rates. The performance of an IC reactor is closely related with hydrodynamic behaviors of anaerobic granules. Typically, anaerobic granules work in swarms and the settling behavior of a granule is disturbed by other granules. However, the research on anaerobic granule swarms is insufficient. In this work, Computational Fluid Dynamics (CFD) method was employed to study the hydrodynamic behaviors of anaerobic granule swarms with various voidages. The simulated results showed that the average velocity inside granules increased significantly as the voidage of granule swarm decreased and as the Reynolds number increased. The maximum shear stress on the granule’s surface increased with decreasing voidage and increasing Reynolds number. Based on the hydrodynamic behaviors of anaerobic granule swarms, an improved model of drag force coefficient for granule swarms was developed. The predicted expanded height, using the improved model, gives better consistency with experimental results. The improved model can embed in CFD code to improve the precision of the description of the IC reactor model and provide valuable information for designing and operating an IC reactor.

Processes for Bioenergy and Resources Recovery from Biowaste

“…The Special Issue showcases ten full-length original research articles [13][14][15][16][17][18][19][20][21][22], one short communication [23], and one review article [24] covering different aspects of various processes for bioenergy and resource recovery from biowaste. Specifically, the accepted manuscripts covered a range of essential topics in the areas of anaerobic digestion, microbial fermentation, and thermochemical conversion targeting various value-added resources, including biogas, syngas, bio-oil, and organic acids ( Figure 1).…”

“…Chowdhury et al [13] proposed a two-stage anaerobic digestion process combining high-solid anaerobic digestion followed by ultrasonication of digestate and wet-type anaerobic digestion for effective biomethane recovery from the organic fraction of municipal solid waste. Dong et al [19] presented a Computational Fluid Dynamics (CFD) simulation on hydrodynamic characteristics of anaerobic granule swarms with various voidages in an internal circulation (IC) anaerobic reactor. Moreover, Wang et al [18] presented another CFD study on the understanding of flow behaviors of gas-liquid inside the vertical riser inside the IC anaerobic reactor.…”

Numerical study of the mixing of micron particles in a vane mixer

“…Xiuqin Dong et al investigated the hydrodynamic behavior of anaerobic particle populations with different void ratios using CFD methods. It was found that the particle population void ratio and Reynolds number affect the mean velocity inside the particles [11] . The effect of rotating blades on micron particles for continuous flow mixing is investigated, the flow field follows the Stokes equations and particle motion is analyzed using particle tracking.…”