Methane and Hydrogen Sulfide Production from the Anaerobic Digestion of Fish Sludge from Recirculating Aquaculture Systems: Effect of Varying Initial Solid Concentrations

• Published in: Fermentation
• Main Authors: Abhinav Choudhury, Christine Lepine, Christopher Good
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2023
• Subjects: biogas; fish waste; biosolid; volatile fatty acids; total solids; Fermentation industries. Beverages. Alcohol; TP500-660; Atlantic salmon; Salmo salar
• Online Access: https://doi.org/10.3390/fermentation9020094; https://doaj.org/article/c7e3443ee4c348f8b243ce3bdaa5bbcf

Recirculating aquaculture systems (RAS) are efficient at solid waste capture and collection but generate a concentrated waste stream. Anaerobic digestion (AD) could be one potential treatment option for RAS facilities. However, the concentration of organic matter in the sludge can significantly affect the biogas quality from AD. This study evaluated the effect of fish sludge (FS) solid concentration on biogas quality. Three FS treatments consisted of different initial total solid concentrations (1.5%, 2.5%, and 3.5%) from a mixture of sludge produced by Atlantic salmon ( Salmo salar ) and rainbow trout ( Oncorhynchus mykiss ). Methane (CH 4 ) production was measured, quantified, and normalized on a volatile solids (VS) basis. The highest solid concentration treatment produced 23% more CH 4 than the lowest solid concentration (519 mL/g VS versus 422 mL/g VS, respectively). Peak CH 4 production occurred on Day 7 for the lowest FS concentration (78.2 mL/day), while the highest FS concentration peaked on Day 11 (96 mL/day). Peak hydrogen sulfide (H 2 S) concentrations ranged from 1803–2074 ppm across treatments, signifying the requirement of downstream unit processes for H 2 S removal from biogas. Overall, this study demonstrated that increasing the FS concentration can significantly enhance CH 4 production without affecting the stability of the digestion process.