Biogeochemical processes in intensive zero-effluent marine fish culture with recirculating aerobic and anaerobic biofilters

Amir Neori, Michael D. Krom, Jaap van Rijn

Research output: Contribution to journalArticlepeer-review


The biogeochemical processes that drive nutrient transformations and recycling in organic marine sediment-water environments were studied for 17 months in a zero-effluent intensive recirculating culture system. The system consisted of a 10 m3 gilthead seabream (Sparus aurata) tank coupled to aerobic and anaerobic water treatment elements. Nutrients and alkalinity were measured in the system to quantify the main biogeochemical processes. Fractions of the carbon fed in feed were found in fish (18.3%) and in sludge (11%); the missing carbon was respired by fish (45%) and by aerobic (8.4%) and anaerobic (7.7%) microorganisms. Fractions of the nitrogen fed in feed were found in fish (15.4%) and in sludge (14.3%); the missing nitrogen was eliminated by nitrification-denitrification. Most of the phosphorus and ash fed in feed and not found in fish accumulated within the sludge in the system. The rates of nitrification, denitrification and sulphate reduction increased with time, reaching 0.3 g N m- 2 d- 1, 53 g N m- 2 d- 1 and 145 g S m- 2 d- 1, respectively. Nitrification developed more rapidly than denitrification, leading at first to nitrate accumulation (to 20 mmol NO3 l- 1 by day 200) and a decrease in alkalinity. Once denitrification surpassed nitrification, nitrate concentrations decreased, eventually being reduced to < 0.3 mmol NO3 l- 1 by day 510, and alkalinity stabilized. Toxic hydrogen sulphide, generated within the anaerobic sludge, was oxidized by oxygen and nitrate as it diffused through the anaerobic-aerobic sediment-water interface. When nitrate levels in the water above the sludge dropped below 2 mmol l- 1, sulphide was also oxidized in the fluidized bed reactor. Denitrification reduced nitrate in the water, respired (jointly with sulphate reduction) carbon in the sludge, oxidized the hydrogen sulphide, and contributed to stabilization of alkalinity and accumulation of polyphosphate in bacteria as a major sink of labile P.

Original languageEnglish
Pages (from-to)235-247
Number of pages13
JournalJournal of Experimental Marine Biology and Ecology
Issue number2
StatePublished - 19 Oct 2007
Externally publishedYes

Bibliographical note

Funding Information:
This research was funded by grant FAIR-CT98-4160 of the Fisheries Directorate-General, European Commission. We thank I Snir for his invaluable assistance during construction of the culture system, which was then operated by V Odintsev. Further thanks to I Lupatsch for advice on chemical analyses of solids, to A Zalmanzon and E Chernova for chemical analyses, to M Schönfeld for ICP-AES analyses, to TH Blackburn, R Mortimer and E Cytryn for helpful consultations, and to several anonymous reviewers for helpful suggestions to the manuscript. [SS]


  • Alkalinity
  • Fish waste treatment
  • Nitrification-denitrification
  • Nutrients
  • Polyphosphate accumulation
  • Sludge
  • Sparus aurata
  • Sulphate reduction

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science


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