Low-alkaline fermentation for efficient short-chain fatty acids production from waste activated sludge by enhancing endogenous free ammonia

Min Ye, Jiongjiong Ye, Jinghuan Luo, Sitong Zhang, Yu You Li, Jianyong Liu

Research output: Contribution to journalArticlepeer-review

Abstract

Alkaline fermentation at pH 10 is an effective method of producing short-chain fatty acids from waste activated sludge, but requires high cost of alkali. In this study, low-alkaline fermentation at pH 9 with enhanced endogenous free ammonia was proposed to improve sludge hydrolysis and short-chain fatty acids production for the first time. The results showed that the release of 210.6 ± 5.9 mg/L of endogenous free ammonia was sufficient for sludge hydrolysis, with a soluble chemical oxygen demand production of 6303.8 ± 45.9 mg/L within 24 h. Following the increase in sludge hydrolysis, ammonia stripping was employed to further improve acidogenesis by eliminating free ammonia inhibition. The final short-chain fatty acids production was 431.4 ± 1.7 mg chemical oxygen demand/g volatile suspended solid, which was even higher than that of regular alkaline fermentation. Furthermore, the theoretical availability of the produced short-chain fatty acids as a carbon source for denitrification was improved by 56.7%. A schematic of a wastewater treatment process employing low-alkaline fermentation of sludge considering carbon neutrality and nutrients recovery was proposed.

Original languageEnglish
Article number122921
JournalJournal of Cleaner Production
Volume275
DOIs
Publication statusPublished - 2020 Dec 1

Keywords

  • Carbon source
  • Endogenous free ammonia
  • Low-alkaline fermentation
  • Short-chain fatty acids
  • Waste activated sludge

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Environmental Science(all)
  • Strategy and Management
  • Industrial and Manufacturing Engineering

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