| 1. |
- Cripps, Simon J., et al.
(författare)
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A review of the design and performance of tanks relevant to flatfish culture
- 1992
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Ingår i: Aquacultural Engineering. - 0144-8609 .- 1873-5614. ; 11:2, s. 71-91
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Tidskriftsartikel (refereegranskat)abstract
- The most promising designs of tanks suitable for turbot (Scophthalmus maximus ) culture are reviewed and relevant biological, hydrodynamic and water quality criteria are identified. Designs used for a range of other species are included where appropriate, because they have contributed to the development of tank technology. Large, carefully managed, shallow, circular tanks, with multiple inlets, a slightly sloping bottom and an even flow distribution, appear in the literature to be most suitable.
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| 2. |
- Goddek, S., et al.
(författare)
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Nutrient mineralization and organic matter reduction performance of RAS-based sludge in sequential UASB-EGSB reactors
- 2018
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Ingår i: Aquacultural Engineering. - : Elsevier BV. - 0144-8609 .- 1873-5614. ; 83, s. 10-19
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Tidskriftsartikel (refereegranskat)abstract
- There is a recognized need for mineralizing aquaculture-derived sludge in aquaponics systems in order to reduce waste production. Many recent studies of aquacultural waste treatment have focused only the production of biogas as opposed to the potential for mineralization of nutrient-rich sludge. Upflow anaerobic sludge blanket (UASB) reactors provide one possible solution for breaking down sludge into bioavailable nutrients that can subsequently be delivered to plants. As such, this study examines the mineralization performance of sequential UASB reactors that are designed with an expanded granular sludge bed (EGSB) and compared to standard aerobic and anaerobic batch reactors. Results of our experiments demonstrate that only chemical oxygen demand reduction is significantly different. An unexpected drop in pH of one of the three reactor systems revealed that a pH below 6 was able to significantly increase the mineralization and mobilization of nutrients. Approximately 25% of phosphorus, potassium, and calcium could also be recovered from the sludge under lower pH conditions, as compared to the mineralization performance of standard UASB reactors running at a higher pH. However, the opposite effect was observed with respect to organic sludge reduction, where diminished performance was observed in the low-pH reactor. The current study implies that anaerobic reactors operating at low pH can potentially contribute towards improved nutrient recovery in multi-loop aquaponics systems and reduction of additive agents for pH control of the hydroponic subsystem. © 2018 Elsevier B.V.
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| 3. |
- Gyllenhammar, Andreas, et al.
(författare)
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A mesocosm fish farming experiment and its implications for reducing nutrient load on a regional scale
- 2008
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Ingår i: Aquacultural Engineering. - : Elsevier BV. - 0144-8609 .- 1873-5614. ; 38:2, s. 117-126
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Tidskriftsartikel (refereegranskat)abstract
- This work presents results from a mesocosm fish farming experiment. The main aim of the work was to put the results from the experiment into a wider context dealing with an approach to get zero - or even - negative nutrient fluxes from fish cage farms on a regional scale. To quantify the nutrient loading of phosphorus and nitrogen from net cage aquaculture, a standard dynamic mass-balance model approach was used. A comparison was made between responses from two feeding scenarios with rainbow trout (Oncorhynchus mykiss). One set was given a commercial pelleted fish food the other food with fresh herring inclusion. We have shown that on a regional scale, a zero nutrient load situation may be achievable if the wild fish from the given region account for about 11% of the fish food. In the mesocosm experiment, we also tested different approaches to calculate the growth of the cultivated fish and one can conclude that there are no major differences in using the different sub-models for the interpretations to get zero emissions but different growth functions do give different dynamic responses for the fish growth. We have also tested if it is important to account for denitrification. Under the given conditions this is not the case. Critical testing of the modelling has been performed with uncertainty and sensitivity analyses and the major uncertainties were identified in the growth pattern of the fish and the mesocosm biomass nutrient uptake rate. We argue that these results imply that, from an eutrophication point of view, fish farming in open net cages can be viewed as an environmental sustainable industry, if the fish feed includes nutrients that originate from the surrounding waters.
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| 4. |
- Moran, Damian
(författare)
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Carbon dioxide degassing in fresh and saline water. II: Degassing performance of an air-lift
- 2010
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Ingår i: Aquacultural Engineering. - : Elsevier BV. - 1873-5614 .- 0144-8609. ; 43:3, s. 120-127
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Tidskriftsartikel (refereegranskat)abstract
- A study was undertaken to measure the efficiency with which carbon dioxide was stripped from freshwater (0 parts per thousand) and saline water (35 parts per thousand NaCl) passing through an air-lift at 15 degrees C. The air-lift was constructed of 50 mm (OD) PVC pipe submerged 95 cm in a tank, had an adjustable air injection rate, and could be adjusted to three lifting heights: 11,16 and 25 cm. The gas to liquid ratio (G:L) was high (similar to 1.9-2.0) at low water discharge rates (Q(w)) and represented the initial input energy required to raise the water up the vertical riser section to the discharge pipe. The air-lift increased in pumping efficiency rapidly thereafter, to a G:L minima of 0.3-0.6 at 60-70 L min(-1). After this point the G:L ratio increased with Q(w), representing decreasing air-lift pumping efficiency. The CO2 concentration of the influent and effluent water was measured using submersible infrared CO2 probes over a range of influent CO2 concentrations. The CO2 mass transfer coefficient [(k(L)a)(20)] ranged from 0.025 to 0.468. Increasing lift height increased mass transfer, which was attributed to both the increased G:L ratio and the contact time inside the air-lift. The relative effect of lift height and pumping rate on mass transfer was such that a 5 cm increase in lift height was approximately equal to a G:L increase of 0.5. The CO2 stripping efficiency was effectively the same between salinities, and the influent CO2 concentration only had a modest effect on CO2 stripping efficiency. At an influent concentration of 40 mg L-1 the CO2 stripping efficiency was 1-3% higher than at an influent of 10 mg L-1. The relatively minor effects of salinity and influent CO2 concentration on stripping efficiency contrasted with a companion study investigating the stripping efficiency of a cascade column. The difference was attributed to the low-to-moderate mass transfer efficiencies of the air-lift. A general equation was derived for the airlift that allows one to calculate the mass transfer coefficient for a given lift height, Q(w), or G:L ratio. The mass transfer coefficient can then be used to calculate the CO2 stripping efficiency for any water type (i.e. temperature, alkalinity, salinity and influent CO2 concentration). (C) 2010 Elsevier By. All rights reserved.
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| 5. |
- Stiller, Kevin Torben, et al.
(författare)
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A novel respirometer for online detection of metabolites in aquaculture research: Evaluation and first applications
- 2013
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Ingår i: Aquacultural Engineering. - : Elsevier BV. - 1873-5614 .- 0144-8609. ; 55, s. 23-31
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Tidskriftsartikel (refereegranskat)abstract
- In this study we describe a novel flow-through respirometer with automated and semi-continuous detection of key water variables. The recirculating aquaculture system was designed to house aquatic organisms in culture-like conditions and allow long-term, high-precision measurements. Nine respirometry tanks (250 L in volume each) housed animals, and a tenth (without animals) acted as a reference tank. A single measurement unit made sequential measurements of each tank to eliminate the problem of sensor variation associated with multi-probe setups. The accuracy of the analyzers in relation to measurement range was: O-2 = 1%; CO2 < 1%; NH3 = 2%; temperature <= 0.25%; and pH +/- 0.01. Dissolved CO2 was measured using air-water equilibration coupled with non-dispersive infrared detection of carrier gas, and NH3 was quantified using a reagent-based assay and spectophotometric autoanalyzer. Though expensive and not common in aquaculture or physiology research, these two automated metabolite analyzers could operate in both fresh and seawater, and offered high precision and accuracy. We report on the performance of these instruments for aquaculture research in two trials using a freshwater (rainbow trout, Oncorhynchus mykiss) and seawater fish species (turbot, Scophthalmus maximus). One of the main constraints imposed by the sequential measurement of multiple tanks was the measurement frequency of each tank. In the aforementioned system, NH3 analyzes took the longest (12 min), followed by CO2 (7 min), O-2 (6 min), and pH (3 mm). (C) 2013 Elsevier B.V. All rights reserved.
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| 6. |
- Hakanson, L, et al.
(författare)
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A new approach to calculate the phosphorus load to lakes from fish farm emissions
- 1998
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Ingår i: AQUACULTURAL ENGINEERING. - : ELSEVIER SCI LTD. - 0144-8609. ; 17:3, s. 149-166
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this study has been to test if phosphorus from fish farms increases annual total phosphorus (TP)-concentrations in lakes (C-TP). Field studies in two Swedish lakes show that the expected rise in C-TP did not occur. The conditions (catchment are
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| 7. |
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| 8. |
- Lobanov, Victor P., et al.
(författare)
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Simultaneous biomethane production and nutrient remineralization from aquaculture solids
- 2023
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Ingår i: Aquacultural Engineering. - : Elsevier BV. - 0144-8609. ; 101
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Tidskriftsartikel (refereegranskat)abstract
- The rapid expansion of the aquaculture industry has brought about a heightened focus on the waste produced by high intensity fish farming. In closed-containment, recirculating aquaculture systems (RAS), fish solids are mechanically separated and/or coagulated before being disposed as waste. Subsequent revalorization is typically limited to the direct dispersal of aquaculture solids onto agricultural fields. Here, we developed a novel, continuous flow, low-cost solids waste treatment system for freshwater and saline RAS. Rotating drum filter backwash was collected as the primary feedstock for anaerobic digestion. A laboratory scale set up was used to monitor the conversion of the solids into a methane-rich (60-80% purity) biogas stream. Iron supplementation (ferric iron at 100 mg/L and 1000 mg/L) improved salt tolerance of the methanogenic community, leading to higher methane yields in a supplemented (FeCl3 at 1000 mg/L) saline treatment than the saline control. The application of iron additionally improves pH stability and volatile fatty acid utilization. The methane yield ranged from 0.1 to 0.4 NL CH4/ g VS across the three freshwater treatments and the iron-supplemented saline treatment, however, it was significantly lower for the saltwater control: ranging between 0.08 and 0.25 NL CH4/ g VS. These values correspond to a percentage yield of 57-86% of the total biomethane potential. Overall, implementing anaerobic digestion for RAS waste valorization may generate significant amounts of biomethane to be used in electricity and heating for large-scale aquaculture facilities, while even for smaller facilities it may off-set costs and mitigate environmental impacts of the waste streams.
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| 9. |
- Pedersen, Simon, 1991, et al.
(författare)
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A comparison of topologies in recirculating aquaculture systems using simulation and optimization
- 2020
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Ingår i: Aquacultural Engineering. - : Elsevier BV. - 0144-8609. ; 89
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Tidskriftsartikel (refereegranskat)abstract
- Recirculating aquaculture systems (RAS) are often designed using simplified steady-state mass balances, which fail to account for the complex dynamics that biological water treatment systems exhibit. Because of the very slow dynamics, experimental development is also difficult. We present a new, fast and robust Modelica implementation of a material balance-based dynamic simulator for fish growth, waste production and water treatment in recirculating aquaculture systems. This simulator is used together with an optimization routine based on a genetic algorithm to evaluate the performance of three different water treatment topologies, each for two fish species (Rainbow trout and Atlantic salmon) and each in both a semi-closed (no denitrification) and a fully recirculating version (with denitrification). Each case is furthermore evaluated at both saturated and supersaturated oxygen levels in the fish tank influent. The 24 cases are compared in terms of volume required to maintain an acceptable TAN concentration in the fish tank. The results indicate that the smallest volume is obtainable by introducing several bypass flows in the treatment system of a semi-closed RAS and that the gains can be significant. We also show that recycling already treated water back upstream in the treatment process degrades performance and that if one wishes to have a fully recirculating system with minimal water exchange, then the flows of oxygen, carbon and nitrogen must be carefully considered. For several of the cases, no optimum with denitrification could be found. We thus demonstrate that the best configuration and operation strategy for water treatment varies with the conditions imposed by the fish culture, illustrating the complexity of RAS plants and the importance of simulations, but also that computer-driven optimal design has the potential to increase the treatment efficiency of biofilters which could lead to cheaper plants with better water quality.
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| 10. |
- Thomas, P. J., et al.
(författare)
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The use of novel optode sensor technologies for monitoring dissolved carbon dioxide and ammonia concentrations under live haul conditions
- 2017
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Ingår i: Aquacultural Engineering. - : Elsevier BV. - 0144-8609. ; 77, s. 89-96
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Tidskriftsartikel (refereegranskat)abstract
- Fish health under live haul transportation on wellboats and in other recirculating aquaculture systems depends on frequent and reliable measurements of water quality, that may change in response to changes in the environmental conditions and treatment processes. While reliable technologies exist for sensors measuring some water quality parameters such as Oxygen concentration and salinity, there is a lack of sensor technologies for the measurement of other critical water quality parameters such as water pCO(2) and NH3 concentrations. Presented is the theory of operation and performance of prototype optical sensors for the measurement of pCO(2) and NH3, as well as the methods used for their calibration and characterization. In order to evaluate the sensor's suitability for aquaculture applications we temporarily installed the sensors on a weliboat and monitored the water quality during the transportation of live mature Atlantic salmon between fish farms and slaughter facilities on the Norwegian coast. Under transportation with different stocking weights and recirculation conditions, the CO2 optode prototypes recorded measurements that coincided with measurements from standard laboratory analysis of spot samples. The pCO(2) concentration in the well throughout the testing was shown to vary between approximately 300ilatm and 20 000 atm. Compared to the pH derived pCO(2) estimation method widely applied in aquaculture, the CO2 optode was more sensitive to small fluctuations in CO2 concentration, and gave measurements closer to the CO2 values recorded by laboratory analysis of spot samples. The NH3 optode reported measurements that were consistent with spot samples analyzed using the salicylate-hypochlorite reaction. In contrast to pCO(2), the concentration of NH3 during the observed weliboat missions was found to be very low and stable at 0.8 0.31.4L(-1). Once fully developed, the CO2 and NH3 optodes could contribute to better water quality control and efficiency during well boat transportations and other recirculating aquaculture systems. (C) 2017 Published by Elsevier B.V.
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