Floating feces: A new approach for efficient removal of solids in aquacultural management

Unger, J.; Brinker, Alexander

doi:10.1016/j.aquaculture.2013.04.015

Cited by 18 publications

(19 citation statements)

References 38 publications

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“…Granules derived from thick phloem rings or ligneous tissues have a higher density than those from other parts of the cork oak cambium (Unger & Brinker 2013b). This problem could be reduced by decreasing cork granule size and narrowing the size range.…”

Section: Discussionmentioning

confidence: 99%

“…The faeces of 10 fish were pooled for testing. As faecal density is influenced by water absorption (Unger & Brinker 2013b), further samples were also measured after being allowed to soak for 1 h in water from the system (Table 2). This soaking time is based on the average retention of water in fish…”

Section: Sampling Of Faecesmentioning

confidence: 99%

“…; Unger & Brinker 2013b) was used as a control diet (Table 1). The experimental diet was the same basic feed, supplemented with 2.5% cork granules (range of grain size: 0.5−1 mm; Amorim; Fig.…”

Section: Feeding Protocolmentioning

confidence: 99%

“…However, it is possible to manipulate the properties of faeces in such a way as to increase mechanical and chemical stability (Brinker & Friedrich 2012) and limit the production of fine particles (Unger & Brinker 2013a). A further promising approach has been the use of functional feed ingredients to reduce faecal density, resulting in the production of floating faeces (Unger & Brinker 2013b) and facilitating rapid and effective waste management in several ways:…”

Section: Introductionmentioning

confidence: 99%

“…• Allowing rapid and almost complete removal of faecal casts • Minimizing leaching of soluble components • Ensuring improved biofilter efficiency and stability • Reducing investment and operating costs by limiting the requirement for solid treatment to surface flow only • Improving water quality and feed utilization, with additional benefits in terms of stock health and welfare • Production of fertilizer-quality sludge, with no need for further thickening Based on extensive laboratory studies (Unger & Brinker 2013b) showing that inclusion of low levels of cork Quercus suber L. granules in trout diet produced faecal casts which float, the present study applies the approach to a commercial environment, examining the effect of an experimental diet and floating faeces on stock health and performance, removal efficiencies (by sedimentation, drum filtration and surface separation), biofilter performance and sludge quality in an operational fish farm, and comparing the outcomes with those of a commercial control diet.…”

Section: Introductionmentioning

confidence: 99%

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Floating faeces for a cleaner fish production

Unger¹,

Schumann²,

Brinker³

2015

Aquacult. Environ. Interact.

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Recent developments in European recirculating aquaculture systems suggest expanding potential for this extremely water-efficient technique. However, the technology still faces challenges due to concerns over economic efficiency and system stability-both essential in minimizing the risk of financially and environmentally expensive failures. One key factor in maintaining stable production conditions in a recirculation loop is the effective removal of solid waste, i.e. fish faeces. This study tested a novel approach for solid control and demonstrates the value-adding potential of floating faeces under commercial conditions in a semi-recirculating fish farm in Germany. A commercial control diet was compared with an experimental diet in which the addition of 2.5% cork granules led to the production of floating faeces. Physiological assays indicated no pathologic tissue alterations associated with the experimental feed, and growth, survival and feed conversion were unaffected. Average single-pass removal by a specially developed surface separator accounted for 78.3% of floating solids, which accounted for 35.4% of total system solids. Total ammonia nitrogen concentrations in production water were roughly halved, from about 0.95 mg l −1 in the control to 0.47 mg l −1 using the cork diet, an improvement that in practice allowed a doubling of production on the same available water flow. This study shows that the application of floating faeces facilitates rapid and cost-effective removal of suspended solids, resulting in a considerable decrease of nutrient load in system and discharge water of the investigated farm.

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Section: Discussionmentioning

confidence: 99%

Section: Sampling Of Faecesmentioning

confidence: 99%

Section: Feeding Protocolmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Floating faeces for a cleaner fish production

Unger¹,

Schumann²,

Brinker³

2015

Aquacult. Environ. Interact.

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Mercury and antimony in wastewater: fate and treatment

Hargreaves

Vale

Whelan

et al. 2016

Water Air Soil Pollut

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It is important to understand the fate of Hg and Sb within the wastewater treatment process so as to examine potential treatment options and to ensure compliance with regulatory standards. The fate of Hg and Sb was investigated for an activated sludge process treatment works in the UK. Relatively high crude values (Hg 0.092 μg/L, Sb 1.73 μg/L) were observed at the works, whilst low removal rates within the primary (Hg 52.2 %, Sb 16.3 %) and secondary treatment stages (Hg 29.5 %, Sb −28.9 %) resulted in final effluent concentrations of 0.031 μg/L for Hg and 2.04 μg/L for Sb. Removal of Hg was positively correlated with suspended solids (SS) and chemical oxygen demand (COD) removal, whilst Sb was negatively correlated. Elevated final effluent Sb concentrations compared with crude values were postulated and were suggested to result from Sb present in returned sludge liquors. Kepner Tregoe (KT) analysis was applied to identify suitable treatment technologies. For Hg, chemical techniques (specifically precipitation) were found to be the most suitable whilst for Sb, adsorption (using granulated ferric hydroxide) was deemed most appropriate. Operational solutions, such as lengthening hydraulic retention time, and treatment technologies deployed on sludge liquors were also reviewed but were not feasible for implementation at the works.

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