Integrated microbial electrolysis with high-alkali pretreated sludge digestion: Insight into the effect of voltage on methanogenesis and substrate metabolism

Ling Wang; Chang Liu; Thangavel Sangeetha; Wei Mon Yan; Fang Sun; Zhiling Li; Xiaodong Wang; Kailing Pan; Aijie Wang; Xuejun Bi; Wenzong Liu

doi:10.1016/j.jenvman.2023.118007

Integrated microbial electrolysis with high-alkali pretreated sludge digestion: Insight into the effect of voltage on methanogenesis and substrate metabolism

J Environ Manage. 2023 Sep 1:341:118007. doi: 10.1016/j.jenvman.2023.118007. Epub 2023 May 4.

Authors

Ling Wang¹, Chang Liu², Thangavel Sangeetha³, Wei Mon Yan³, Fang Sun⁴, Zhiling Li⁵, Xiaodong Wang², Kailing Pan², Aijie Wang⁶, Xuejun Bi², Wenzong Liu⁷

Affiliations

¹ School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao, 266000, PR China; State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150000, PR China.
² School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao, 266000, PR China.
³ Research Center of Energy Conservation for New Generation of Residential, Commercial, and Industrial Sectors, National Taipei University of Technology, Taipei 10608, Taiwan; Department of Energy and Refrigerating Air-Conditioning Engineering, National Taipei University of Technology, Taipei, 10608, Taiwan.
⁴ Heilongjiang Province Key Laboratory of Superhard Materials, Department of Physics, Mudanjiang Normal University, Mudanjiang, 157012, PR China.
⁵ State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150000, PR China.
⁶ State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150000, PR China; School of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen, 518000, PR China.
⁷ State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150000, PR China; School of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen, 518000, PR China. Electronic address: liuwenzong@hit.edu.cn.

PMID: 37148763
DOI: 10.1016/j.jenvman.2023.118007

Abstract

Integrated microbial electrolysis with anaerobic digestion is proved to be an effective way to improve methanogenesis efficiency of waste activated sludge (WAS). WAS requires pretreatment for efficient improvement of acidification or methanogenesis efficiency, but excessive acidification may inhibit the methanogenesis. In order to balance these two stages, a method for efficient WAS hydrolysis and methanogenesis has been proposed in this study by high-alkaline pretreatment integrated with microbial electrolysis system. The effects of pretreatment methods and voltage on the normal temperature digestion of WAS have also been further investigated with emphasis on the effects of voltage and substrate metabolism. The results show that compared to low-alkaline pretreatment (pH = 10), high-alkaline pretreatment (pH > 14) can double the SCOD release and promote the VFAs accumulation to 5657 ± 392 mg COD/L, but inhibit the methanogenesis process. Microbial electrolysis can alleviate this inhibition effectively through the rapid consumption of VFAs and speeding up of the methanogenesis process. The optimal methane yield of the integrated system is 120.4 ± 8.4 mL/g VSS at the voltage of 0.5 V. Enzyme activities, high-throughput and gene function prediction analysis reveal that the cathode and anode maintain the activity of methanogens under high substrate concentrations. Voltage positively responded to improved methane yield from 0.3 to 0.8 V, but higher than 1.1 V is found to be unfavorable for cathodic methanogenesis and results in additional power loss. These findings provide a perspective idea for rapid and maximum biogas recovery from WAS.

Keywords: Bioelectrolysis; High-alkaline pretreatment; Methane; Voltage; Waste activated sludge.

MeSH terms

Alkalies*
Anaerobiosis
Bioreactors
Digestion
Electrolysis
Methane
Sewage*

Substances

Alkalies
Sewage
Methane