Numerical study of hydrodynamic characteristics in a moving bed biofilm reactor

Jing Wang; XianBin Ying; YongHao Huang; YuQi Chen; DongSheng Shen; Xiang Zhang; Hua Jun Feng

doi:10.1016/j.envres.2020.110614

Numerical study of hydrodynamic characteristics in a moving bed biofilm reactor

Environ Res. 2021 Mar:194:110614. doi: 10.1016/j.envres.2020.110614. Epub 2020 Dec 17.

Authors

Jing Wang¹, XianBin Ying¹, YongHao Huang¹, YuQi Chen¹, DongSheng Shen¹, Xiang Zhang², Hua Jun Feng³

Affiliations

¹ School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310012, Zhejiang, China; Instrumental Analysis Center of Zhejiang Gongshang University, Hangzhou, 310012, Zhejiang, China.
² School of Energy and Power Engineering, Xihua University, Chengdu, 610039, Sichuan, China. Electronic address: zhangxiang@mail.xhu.edu.cn.
³ School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310012, Zhejiang, China; Instrumental Analysis Center of Zhejiang Gongshang University, Hangzhou, 310012, Zhejiang, China. Electronic address: fenghuajun@mail.zjgsu.edu.cn.

PMID: 33345900
DOI: 10.1016/j.envres.2020.110614

Abstract

The moving bed biofilm reactor (MBBR) has certain advantages, such as high wastewater treatment efficiency, low maintenance and operating costs, and simple operation. It has emerged as a valuable option for small decentralized facilities. The filling ratio, aeration mode and aeration intensity are the main factors that affect the performance of MBBRs in wastewater treatment. However, the information that concerns the used criteria that pertain to the process design for the MBBR is not adequate. In this study, a three dimensional computational fluid dynamics (CFD) model was constructed and the maximum error was only 1.98%, which was much smaller than the traditional 2D-CFD model. The filling ratio, aeration mode and aeration intensity of MBBR were optimized by CFD model from the point of view of fluid mechanics. The results show that the fluidization performance of the filling is the best under the one-side aeration mode with 30% filling ratio. The cost-performance ratio of the reactor with 30% filling ratio was 1.53, 25% and 35% filling ratio were only 1.17 and 1.14 respectively. Increasing the aeration intensity could improve the fluidization performance. However, the effect of high aeration intensity on the fluidization performance of the carrier was limited and the energy consumption increased greatly. The results revealed that when the aeration intensity increased from 0.07 min^-1 to 0.13 min^-1, the proportion of the carrier area increased by 16.56%. The proportion of the carrier area with an aeration rate of 0.20 min^-1 was only 4.23%, which is higher than 0.13 min^-1. The main factors that control the fluidization of the carrier were the range of the flow zone and the flow velocity of the liquid. Increasing the range of the flow zone could facilitate the flow of the carriers. The critical value of the flow velocity of the liquid in the flow zone was 0.04 m/s. These results could guide the optimization design of the filling ratio and the aeration conditions and provide a theoretical basis for the application of MBBR.

Keywords: CFD model; Filling ratio; Fluidized performance; Hydrodynamic characteristic; MBBR.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biofilms*
Bioreactors
Hydrodynamics
Waste Disposal, Fluid
Wastewater
Water Purification*

Substances

Waste Water