Potassium ferrate addition as an alternative pre-treatment to enhance short-chain fatty acids production from waste activated sludge

- First study to assess effects of PF on WAS anaerobic fermentation/digestion.
- PF enhanced the production of HAc-enriched SCFAs.
- PF favored both EPSs and cells disintegration, and cells contributed 73.0% DOMs.
- Microbial activity and community related to SCFAs production were identified.
- A potential solution to recover carbon source from WAS was proposed.

A potentially practical technology based on ferrate (VI), i.e. potassium ferrate (PF), pretreatment integrated into waste activated sludge (WAS) anaerobic fermentation has been presented to greatly enhance short-chain fatty acids (SCFAs) production with a shortened fermentation time. The maximum production of SCFAs, 343 mg chemical oxygen demand/g volatile suspended solid with acetic acid proportion of 48.2%, was obtained with PF dosage of 56 mg Fe(VI)/g total suspended solid within 5 days, which was increased to 5.72 times compared to that of control. The mechanism study showed that PF accelerated the release rate of both intracellular and extracellular constituents. And the activities of key hydrolytic enzymes were much improved with PF addition. Moreover, PF positively enriched the abundance of microorganisms responsible for WAS hydrolysis and SCFAs production, especially acetic acid-forming characteristic genera such as Petrimonas, Fusibacter and Acetoanaerobium. Besides, the incubation time of acidogenesis and methanogenesis were separated by PF.

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