Contribution identification of hydrolyzed products of potassium ferrate on promoting short-chain fatty acids production from waste activated sludge

Cong-Cong Tang; Min Zhang; Bo Wang; Zheng-Shuo Zou; Xing-Ye Yao; Ai-Juan Zhou; Wenzong Liu; Yong-Xiang Ren; Zhi-Hua Li; Aijie Wang; Zhang-Wei He

doi:10.1016/j.jenvman.2023.118886

Contribution identification of hydrolyzed products of potassium ferrate on promoting short-chain fatty acids production from waste activated sludge

J Environ Manage. 2023 Nov 1:345:118886. doi: 10.1016/j.jenvman.2023.118886. Epub 2023 Sep 4.

Authors

Cong-Cong Tang¹, Min Zhang¹, Bo Wang², Zheng-Shuo Zou¹, Xing-Ye Yao¹, Ai-Juan Zhou³, Wenzong Liu⁴, Yong-Xiang Ren¹, Zhi-Hua Li¹, Aijie Wang⁴, Zhang-Wei He⁵

Affiliations

¹ Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China.
² Center for Electromicrobiology, Section for Microbiology, Department of Biology, Aarhus University, 8000, Aarhus C, Denmark.
³ College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, 030024, China.
⁴ State Key Laboratory of Urban Water Resource and Environment, School of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen, 518055, China.
⁵ Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China. Electronic address: zwhe@xauat.edu.cn.

PMID: 37673008
DOI: 10.1016/j.jenvman.2023.118886

Abstract

Potassium ferrate (K₂FeO₄) has been extensively employed to promote short-chain fatty acids (SCFAs) production from anaerobic fermentation of waste activated sludge (WAS) because of its potent oxidizing property and formation of alkaline hydrolyzed products (potassium hydroxide, KOH and ferric hydroxide, Fe(OH)₃). However, whether K₂FeO₄ actually works as dual functions of both an oxidizing agent and an alkalinity enhancer during the anaerobic fermentation process remains uncertain. This study aims to identify the contributions of hydrolyzed products of K₂FeO₄ on SCFAs production. The results showed that K₂FeO₄ did not execute dual functions of oxidization and alkalinity in promoting SCFAs production. The accumulation of SCFAs using K₂FeO₄ treatment (183 mg COD/g volatile suspended solids, VSS) was less than that using either KOH (192 mg COD/g VSS) or KOH & Fe(OH)₃ (210 mg COD/g VSS). The mechanism analysis indicated that the synergistic effects caused by oxidization and alkalinity properties of K₂FeO₄ did not happen on solubilization, hydrolysis, and acidogenesis stages, and the inhibition effect caused by K₂FeO₄ on methanogenesis stage at the initial phase was more severe than that of its hydrolyzed products. It was also noted that the inhibition effects of K₂FeO₄ and its hydrolyzed products on the methanogenesis stage could be relieved during a longer sludge retention time, and the final methane yields using KOH or KOH & Fe(OH)₃ treatment were higher than that using K₂FeO₄, further confirming that dual functions of K₂FeO₄ were not obtained. Therefore, K₂FeO₄ may not be an alternative strategy for enhancing the production of SCFAs from WAS compared to its alkaline hydrolyzed products. Regarding the strong oxidization property of K₂FeO₄, more attention could be turned to the fates of refractory organics in the anaerobic fermentation of WAS.

Keywords: Anaerobic fermentation; Hydrolyzed products; Potassium ferrate; Short-chain fatty acids; Waste activated sludge.

MeSH terms

Fatty Acids, Volatile
Potassium Compounds*
Sewage*

Substances

potassium ferrate
Sewage
potassium hydroxide
Potassium Compounds
Fatty Acids, Volatile