Ionic liquid coupled plasma promotes acetic acid production during anaerobic fermentation of waste activated sludge: Breaking the restrictions of low bioavailable substrates and altering the metabolic activities of anaerobes

•[Emim]OTf/DBD synergistically enhanced SCFA production during sludge fermentation.•Solubilization, hydrolysis, and acidogenesis were facilitated by [Emim]OTf/DBD.•[Emim]OTf/DBD promoted the generation of •OH, 1O2, •O2− and ONOO−.•[Emim]OTf/DBD enriched SCFA-forming bacteria and decreased SCFA-consu...

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Bibliographic Details
Published in:Water research (Oxford) 2024-09, Vol.261, p.122048, Article 122048
Main Authors: He, Jinling, Jiang, Xinyuan, Qiu, Qi, Miruka, Andere Clement, Xu, Xianbao, Zhang, Ai, Li, Xiang, Gao, Pin, Liu, Yanan
Format: Article
Language:English
Subjects:
Dielectric barrier discharge plasma
Ionic liquid
Short-chain fatty acids
Waste activated sludge
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Summary:•[Emim]OTf/DBD synergistically enhanced SCFA production during sludge fermentation.•Solubilization, hydrolysis, and acidogenesis were facilitated by [Emim]OTf/DBD.•[Emim]OTf/DBD promoted the generation of •OH, 1O2, •O2− and ONOO−.•[Emim]OTf/DBD enriched SCFA-forming bacteria and decreased SCFA-consuming bacteria.•[Emim]OTf/DBD favored sludge dewatering and heavy metal removal. This study explored the potential application of plasma coupling ionic liquid on disintegration of waste activated sludge and enhanced production of short-chain fatty acids (SCFAs) in anaerobic fermentation. Under optimal conditions (dosage of ionic liquid [Emim]OTf = 0.1 g/g VSS (volatile suspended solids) and discharge power of dielectric barrier discharge plasma (DBD) = 75.2 W), the [Emim]OTf/DBD pretreatment increased SCFA production by 302 % and acetic acid ratio by 53 % compared to the control. Mechanistic investigations revealed that the [Emim]OTf/DBD combination motivated the generation of various reactive species (such as H2O2, O3, •OH, 1O2, ONOO−, and •O2−) and enhanced the utilization of physical energies (such as heat). The coupling effects of [Emim]OTf/DBD synergistically improved the disintegration of sludge and biodegradability of dissolved organic matter, promoting the sludge anaerobic fermentation process. Moreover, the [Emim]OTf/DBD pretreatment enriched hydrolysis and SCFAs-forming bacteria while inhibiting SCFAs-consuming bacteria. The net effect was pronounced expression of genes encoding key enzymes (such as alpha-glucosidase, endoglucanase, beta-glucosidase, l-lactate/D-lactate dehydrogenase, and butyrate kinase) involved in the SCFA-producing pathway, enhancing the production of SCFAs from sludge anaerobic fermentation. In addition, [Emim]OTf/DBD pretreatment facilitated sludge dewatering and heavy metal removal. Therefore, [Emim]OTf/DBD pretreatment is a promising approach to advancing sludge reduction, recyclability, and valuable resource recovery. [Display omitted]
ISSN:0043-1354
1879-2448
1879-2448
DOI:10.1016/j.watres.2024.122048