The composition of readily available carbon sources produced by fermentation of fish faeces is affected by dietary protein:energy ratios

Carlos Octavio Letelier-Gordo, Bodil Katrine Larsen, Johanne Dalsgaard, Per Bovbjerg Pedersen

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Fish solid waste (faeces) produced in recirculated aquaculture systems (RAS) might be used for on-farm, single-sludge denitrification if transformed into soluble organic carbon substances. The current study investigated the effect of feeding diets with increasing protein to energy ratios (P:E_15, 17, 19, 21 and 23 g/MJ) to rainbow trout (Oncorhynchus mykiss) on the production of volatile fatty acids (VFAs) and ethanol during 7 days fermentation of the produced fish faeces. The total yields of VFAs and ethanol obtained (expressed as chemical oxygen demand (COD)) ranged between 0.21–0.24 gCOD/gTCOD, showing no differences between treatments. However, the type and quantities of individual VFAs and ethanol changed according to the dietary treatment. Lower P:E ratio diets resulted in higher production of butyric acid and ethanol, whereas higher P:E ratio diets resulted in an increased production of acetic and valeric acid. Changing the diet composition thus affects the composition of readily available carbon that can be derived from the faeces. This can be applied to enhance on-farm single sludge denitrification and reduce the need for adding external carbon sources such as e.g. methanol.
Original languageEnglish
JournalAquacultural Engineering
Volume77
Pages (from-to)27-32
ISSN0144-8609
DOIs
Publication statusPublished - 2017

Keywords

  • Aquatic Science
  • Ethanol
  • Fermentation
  • Protein:energy
  • Single-sludge denitrification
  • VFAs
  • Butyric acid
  • Chemical oxygen demand
  • Denitrification
  • Fatty acids
  • Fish
  • Organic carbon
  • Proteins
  • Aquaculture systems
  • Carbon source
  • Dietary proteins
  • Dietary treatments
  • Rainbow trouts (Oncorhynchus mykiss)
  • Valeric acids
  • Volatile fatty acids (VFAs)
  • Volatile fatty acids
  • Oncorhynchus mykiss

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