Semi-aerobic fermentation as a novel pre-treatment to obtain VFA and increase methane yield from primary sludge. (January 2016)

• Record Type: Journal Article
• Authors: Peces, M.; Astals, S.; Clarke, W.P.; Jensen, P.D.
• Is Part Of: Bioresource technology. Volume 200(2016)
• Page Start: 631
• Page End: 638
• Publication Date: 2016-01
• Subjects: Fermentation -- Anaerobic digestion -- Sewage sludge -- Temperature -- Fungi; 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.2015.10.085
• Languages: English
• ISSNs: 0960-8524

Abstract

Highlights: Temperature of primary sludge fermentation affected acidification yield and profile. Fermentation at 20 and 35 °C led to VFA, while 55 and 70 °C led to other soluble material. VFA removal after 37, 55, and 70 °C fermentation lowered 20% sludge methane potential. Semi-aerobic conditions at 20 °C improved methane yield even after VFA removal. Fungi colonised the sludge top layer under 20 °C semi-aerobic conditions. Abstract: There is a growing trend to consider organic wastes as potential sources of renewable energy and value-add products. Fermentation products have emerged as attractive value-add option due to relative easy production and broad application range. However, pre-fermentation and extraction of soluble products may impact down-stream treatment processes, particularly energy recovery by anaerobic digestion. This paper investigates primary sludge pre-fermentation at different temperatures (20, 37, 55, and 70 °C), treatment times (12, 24, 48, and 72 h), and oxygen availability (semi-aerobic, anaerobic); and its impact on anaerobic digestion. Pre-fermentation at 20 and 37 °C succeeded for VFA production with acetate and propionate being major products. Pre-fermentation at 37, 55, and 70 °C resulted in higher solubilisation yield but it reduced sludge methane potential by 20%. Under semi-aerobic conditions, pre-fermentation allowed both VFA recovery (43 g CODVFA kg −1 VS) and improved methane potential. The latter phenomenon was linked to fungi that colonised the sludge top layer during pre-fermentation.