Transforming waste activated sludge into medium chain fatty acids in continuous two-stage anaerobic fermentation: Demonstration at different pH levels

Wu，Shu Lin1; Wei，Wei2; Wang，Yun1; Song，Lan3; Ni，Bing Jie2

2022-02-01

10.1016/j.chemosphere.2021.132474

CHEMOSPHERE   影响因子和分区

0045-6535

1879-1298

Bioenergy recovery in the form of medium-chain fatty acids (MCFAs) from waste activated sludge (WAS) is increasingly attractive, which are valuable building blocks for fuel production. This study experimentally demonstrated the long-term MCFAs (C6–C8) production from WAS in two-stage anaerobic sludge fermentation at different pH conditions, using continuously operated bench-scale anaerobic reactors. The WAS was continuously converted to short chain fatty acids (SCFAs, 3500–3800 mg chemical oxygen demand (COD)/L) at the first stage via alkaline anaerobic fermentation, which was directly fed into the second stage as both substrates and inoculum for MCFAs production through chain elongation (CE). The productions of MCFAs at the second stage were continuously studied under three different pH conditions (i.e., 10, 7 and 5.5). The results demonstrated that there was no significant MCFAs production at pH 10 during the steady state, whereas the MCFAs productions were clearly observed at both pH 7 and pH 5.5, with much higher MCFAs production from WAS at pH 7 (i.e., 10.32 g COD/L MCFAs) than that at pH 5.5 (i.e., 8.73 g COD/L MCFAs) during the steady state. A higher MCFAs selectivity of 62.3% was also achieved at pH 7. The relatively lower MCFAs production and selectivity at pH 5.5 was likely due to the higher undissociated MCFAs generated at pH 5.5, which would pose toxicity impact on CE microbes and thus inhibit the CE process. Microbial community analysis confirmed that the relative abundances of CE related microbes (e.g., Clostridium sensu stricto 12 sp. and Clostridium sensu stricto 1) increased at pH 7 compared to those at pH 5.5, which enabled more efficient MCFAs production from WAS.

Anaerobic fermentation Medium-chain fatty acids Microbial community pH level Two-stage Waste activated sludge

SCI ; EI

英语

其他

Australian Research Council (ARC) Future Fellowship[FT160100195] ; ARC[DE220100530]

Environmental Sciences & Ecology

Environmental Sciences

WOS:000710190500009

PERGAMON-ELSEVIER SCIENCE LTD

20214010987578

Alkalinity ; Clostridium ; Fermentation ; pH ; Substrates ; Volatile fatty acids

Biology:461.9 ; Chemistry, General:801.1 ; Organic Compounds:804.1

ENVIRONMENT/ECOLOGY

2-s2.0-85116358807

Scopus

1.State Key Laboratory of Pollution Control and Resources Reuse,College of Environmental Science and Engineering,Tongji University,Shanghai,200092,China
2.Centre for Technology in Water and Wastewater,School of Civil and Environmental Engineering,University of Technology Sydney,Sydney,2007,Australia
3.School of Environmental Science and Engineering,Southern University of Science and Technology,Shenzhen,518055,China

Wu，Shu Lin,Wei，Wei,Wang，Yun,et al. Transforming waste activated sludge into medium chain fatty acids in continuous two-stage anaerobic fermentation: Demonstration at different pH levels[J]. CHEMOSPHERE,2022,288.

Wu，Shu Lin,Wei，Wei,Wang，Yun,Song，Lan,&Ni，Bing Jie.(2022).Transforming waste activated sludge into medium chain fatty acids in continuous two-stage anaerobic fermentation: Demonstration at different pH levels.CHEMOSPHERE,288.

Wu，Shu Lin,et al."Transforming waste activated sludge into medium chain fatty acids in continuous two-stage anaerobic fermentation: Demonstration at different pH levels".CHEMOSPHERE 288(2022).