Enhanced volatile fatty acid production from excess sludge by combined free nitrous acid and rhamnolipid treatment. (January 2017)

• Record Type: Journal Article
• Authors: Wu, Qing-Lian; Guo, Wan-Qian; Bao, Xian; Zheng, He-Shan; Yin, Ren-Li; Feng, Xiao-Chi; Luo, Hai-Chao; Ren, Nan-Qi
• Is Part Of: Bioresource technology. Volume 224(2017)
• Page Start: 727
• Page End: 732
• Publication Date: 2017-01
• Subjects: Excess sludge -- Volatile fatty acid -- Free nitrous acid -- Rhamnolipid -- Pretreatment; Biomass -- Periodicals; Biomass energy -- Periodicals; Bioremediation -- Periodicals; Agricultural wastes -- Periodicals; Factory and trade waste -- Periodicals; Organic wastes -- Periodicals; Bioénergie -- Périodiques; Déchets agricoles -- Périodiques; Déchets industriels -- Périodiques; Déchets organiques -- Périodiques; Déchets (Combustible) -- Périodiques; 662.88
• DOI: 10.1016/j.biortech.2016.10.086
• Languages: English
• ISSNs: 0960-8524

Abstract

Graphical abstract: Highlights: FNA+RL treatment enhanced VFA production and shortened fermentation time. RL addition improved the percentage and production of propionic acid. Biodegradability of sludge was improved by FNA pretreatment and RL addition. FNA+RL treatment got a positive synergetic effect on VFA production. FNA+RL treatment raised hydrolytic/acidogenic bacteria but inhibited methanogens. Abstract: VFA production from excess sludge (ES) was greatly enhanced by a low-cost and high-efficient treatment: 0.67 mg/L free nitrous acid (FNA) pretreatment combined with 0.04 g/g TSS rhamnolipid (RL) addition (FNA+RL), which significantly shortened fermentation time to 3 days and increased VFA production to 352.26 mg COD/g VSS (5.42 times higher than raw ES). Propionic and acetic acids were the two leading components (71.86% of the total VFA). Mechanism investigation manifested FNA+RL improved the biodegradability of ES, achieved positive synergetic effect on solubilization, hydrolysis and acidification efficiencies, and inhibited methanation. Microbial community distribution further explained the above phenomena. The bacteria related to polysaccharides/protein utilization and VFA generation, including Clostridium, Megasphaera and Proteiniborus, were mainly observed in FNA+RL, whereas gas-forming bacteria Anaerolineae and acid-consuming bacteria Proteobacteria were assuredly suppressed. Besides, Propionibacterineae associated with propionic acid generation was exclusively enriched in sole RL and FNA+RL.