Recirculation ratio regulates denitrifying sulfide removal and elemental sulfur recovery by altering sludge characteristics and microbial community composition in an EGSB reactor

Fan Chen; Zhi-Ling Li; Miao Lv; Cong Huang; Bin Liang; Ye Yuan; Xiao-Qiu Lin; Xiang-Yu Gao; Ai-Jie Wang

doi:10.1016/j.envres.2019.108905

Recirculation ratio regulates denitrifying sulfide removal and elemental sulfur recovery by altering sludge characteristics and microbial community composition in an EGSB reactor

Environ Res. 2020 Feb:181:108905. doi: 10.1016/j.envres.2019.108905. Epub 2019 Nov 9.

Authors

Fan Chen¹, Zhi-Ling Li², Miao Lv¹, Cong Huang¹, Bin Liang³, Ye Yuan⁴, Xiao-Qiu Lin¹, Xiang-Yu Gao¹, Ai-Jie Wang⁵

Affiliations

¹ State Key Laboratory of Urban Water Resources and Environment, School of Environment, Harbin Institute of Technology, Harbin, 150090, China.
² State Key Laboratory of Urban Water Resources and Environment, School of Environment, Harbin Institute of Technology, Harbin, 150090, China. Electronic address: lzlhit@163.com.
³ Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
⁴ Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; School of Environmental Science and Engineering, Yancheng Institute of Technology, Yancheng, 224051, China.
⁵ State Key Laboratory of Urban Water Resources and Environment, School of Environment, Harbin Institute of Technology, Harbin, 150090, China; Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China. Electronic address: waj0578@hit.edu.cn.

PMID: 31767354
DOI: 10.1016/j.envres.2019.108905

Abstract

Expanded granular sludge blanket (EGSB) is regarded as a promising reactor to carry out denitrifying sulfide removal (DSR) and elemental sulfur (S⁰) recovery. Although the recirculation ratio is an essential parameter for EGSB reactors, how it impacts the DSR process remains poorly understood. Here, three lab-scale DSR-EGSB reactors were established with the different recirculation ratios (3:1, 6:1 and 9:1) to evaluate the corresponding variations in pollutant removal, S⁰ recovery, anaerobic granular sludge (AGS) characteristics and microbial community composition. It was found that an intermediate recirculation ratio (6:1) could facilitate long-term reactor stability. Adequate recirculation ratio could enhance S⁰ recovery, but an excessive recirculation ratio (9:1) was likely to cause AGS fragmentation and biomass loss. The S⁰ desorbed more from sludge at higher recirculation ratios, probably due to the enhanced hydraulic disturbance caused by the increased recirculation ratios. At the low recirculation ratio (3:1), S⁰ accumulation as inorganic suspended solids in AGS led to a decrease in VSS/TSS ratio and mass transfer efficiency. Although typical denitrifying and sulfide-oxidizing bacteria (e.g., Azoarcus, Thauera and Arcobacter) were predominant in all conditions, facultative and heterotrophic functional bacteria (e.g., Azoarcus and Thauera) were more adaptable to higher recirculation ratios than autotrophs (e.g., Arcobacter, Thiobacillus and Vulcanibacillus), which was conducive to the formation of bacterial aggregates to response to the increased recirculation ratio. The study revealed recirculation ratio regulation significantly impacted the DSR-EGSB reactor performance by altering AGS characteristics and microbial community composition, which provides a novel strategy to improve DSR performance and S⁰ recovery.

Keywords: Denitrifying sulfide removal; Elemental sulfur recovery; Expanded granular sludge blanket (EGSB); Microbial community composition; Recirculation ratio.

Publication types

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

MeSH terms

Bioreactors*
Microbiota*
Sewage
Sulfides
Sulfur*

Substances

Sewage
Sulfides
Sulfur