Effects of mixing time on methane production from anaerobic co-digestion of food waste and chicken manure: Experimental studies and CFD analysis

Liwei Mao; Jingxin Zhang; Yanjun Dai; Yen-Wah Tong

doi:10.1016/j.biortech.2019.122177

Effects of mixing time on methane production from anaerobic co-digestion of food waste and chicken manure: Experimental studies and CFD analysis

Bioresour Technol. 2019 Dec:294:122177. doi: 10.1016/j.biortech.2019.122177. Epub 2019 Sep 21.

Authors

Liwei Mao¹, Jingxin Zhang², Yanjun Dai³, Yen-Wah Tong⁴

Affiliations

¹ NUS Environmental Research Institute, National University of Singapore, 1 Create Way, Create Tower #15-02, Singapore 138602, Singapore; Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore.
² China-UK Low Carbon College, Shanghai Jiaotong University, 3 YinlianRoad, Shanghai 201306, China.
³ School of Mechanical Engineering, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China.
⁴ NUS Environmental Research Institute, National University of Singapore, 1 Create Way, Create Tower #15-02, Singapore 138602, Singapore; Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore. Electronic address: chetyw@nus.edu.sg.

PMID: 31563113
DOI: 10.1016/j.biortech.2019.122177

Abstract

The relationship between mixing time and methane production was investigated by anaerobically co-digesting food waste (FW) and chicken manure (CM) at four different organic loading rates. The mixing pattern and turbulence intensity obtained from CFD were adopted to evaluate the mixing performance in digesters with different viscosities. The simulated mixing time from CFD was selected as a reference for the first time to analyze the methane yield. The results showed that if the digester was well mixed under intermittent mixing mode with relatively short mixing time, then extending mixing time or changing intermittent mixing to continuous mixing would have no substantial effects on methane production. By contrast, continuously mixed digesters performed better when the intermittent mixing modes cannot make the digester get to a high degree of uniformity. Hence, the simulated mixing time from CFD can be used as a reference to determine the experimental mixing time in different cases.

Keywords: Co-digestion; Computational Fluid Dynamics (CFD); Methane production; Mixing; Simulated mixing time.

MeSH terms

Anaerobiosis
Animals
Bioreactors
Chickens
Food
Manure*
Methane
Refuse Disposal*

Substances

Manure
Methane