Enhancing energy recovery from aquaculture residual materials: a focus on anaerobic digestion of African catfish (Clarias gariepinus) sediment sludge

Autor: Klein, J; Schüch, A; Foth, S; Sprafke, J; Bischoff, A; Nelles, M; Palm, HW
In:

Frontiers in Sustainable Food Systems

Bandangabe: 8
Auflage: 1397491
Gesamttitelundnr1: Enhancing energy recovery from aquaculture residual materials: a focus on anaerobic digestion of African catfish (Clarias gariepinus) sediment sludge
Ergaenzung: 1397491
ISBN: 2571-581X
DOI: https://doi.org/10.3389/fsufs.2024.1397491
Seite: 1 - 13
Jahr: 2024

Einordung:
Institut: Professur Aquakultur und Sea-Ranching

Abstract:
In Germany, warm water Recirculating Aquaculture Systems (RAS) are generally
integrated with biogas plants. The process sludge produced in aquaculture
could be utilized to generate energy. This study investigates the potential of
process sludge from commercial African catfish (Clarias gariepinus) warm
water RAS, alongside associated plant production residues (whole plants and
pruning residues) for energy generation through anaerobic digestion. Biogas
tests, including batch, semi-Continuous Stirred Tank Reactor (CSTR), and
Upflow Anaerobic Sludge Blanket Reactor (UASB) were conducted. In batch,
methane yields were 229 L(N) / kg VS from the sludge and 173–184 L(N) / kg
VS from the various plant substrates (cucumber, paprika, and tomato plants).
During CSTR operation, mono-fermentation of sludge produced a methane
yield of 265 L(N) / kg VS. Co-fermentation with 25% cucumber residues, based
on VS, increased this value to 381 L(N) / kg VS. Mono-fermentation of sludge
in the UASB reactor yielded a maximum of 329 L(N) /kg VS. The relatively low
TS content and unfavorable C/N ratio in C. gariepinus sludge, along with the
low energy density and occasional high sulfur content in the investigated plant
substrates, present challenges for CSTR biogas production. These challenges can
be partially mitigated through substrate combination. For mono-fermentation of
African catfish RAS sludge, the UASB reactor is recommended. Improved solids
separation, extraction, and concentration techniques at aquaculture operations
are essential for the efficient utilization of aquaculture sludge, especially from
African catfish, in biogas plants.

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