Survey of large circular and octagonal tanks operated at Norwegian commercial smolt and post-smolt sites

AbstractA survey was conducted to determine the geometry, operating parameters, and other key features of large circular or octagonal culture tanks used to produce Atlantic salmon smolt and post-smolt at six major Norwegian Atlantic salmon production companies. A total of 55 large tanks were reported at seven land-based hatchery locations, i.e., averaging 7.9 (range of 4–12) large tanks per land-based site. In addition, one 21,000m3 floating fiberglass tank in sea was reported. Culture volume ranged from 500 to 1300m3 for each land-based tank. Most tanks were circular, but one site used octagonal tanks. Land-based tank diameters ranged from 14.5 to 20m diameter, whereas the floating tank was 40m diameter. Maximum tank depths ranged from 3.5 to 4.5m at land-based facilities, which produced diameter-to-average-depth ratios of 3.6:1 to 5.5:1m:m. The floating tank was much deeper at 20m, with a diameter-to-average-depth ratio of only 2.4:1m:m. All land-based tanks had floors sloping at 4.0–6.5% toward the tank center and various pipe configurations that penetrated the culture tank water volume at tank center. These pipes and sloping floors were used to reduce labor when removing dead fish and harvesting fish.Maximum flow ranged from 3 to 19m3/min per land-based tank, with 400m3/min at the floating tank, but tank flow was adjustable at most facilities. Land-based tanks were flushed at a mean hydraulic retention time (HRT) of 35–170min. Maximum feed load on each land-based tank ranged from 525 to 850kg/day, but the floating tank reached 3700kg/day. Almost half of the large tanks reported in this survey were installed or renovated since 2013, including the three tank systems with the highest flow rate per tank (greater than 17.6m3/min). These more recent tanks were operated at more rapid tank HRT’s, i.e., from 34.8 to 52.5min, than the 67–170min HRT typical of the large tanks built before 2013. In addition, flow per unit of feed load in land-based tanks that began operating before 2010 were lower (19–30m3 flow/kg feed) than in tanks that began operating later (33–40m3 flow/kg feed). In comparison, the floating tank operates at a maximum daily tank flow to feed load of 160m3 flow/kg feed, which is the least intensive of all tanks surveyed. Survey results suggest that the recently built tanks have been designed to operate at a reduced metabolic loading per unit of flow, a tendency that would improve water quality throughout the culture tank, all else equal. This trend is possible due to the ever increasing application of water recirculating systems

Photoperiod in recirculation aquaculture systems and timing of seawater transfer affect seawater growth performance of Atlantic salmon (Salmo salar)

Production of Atlantic salmon smolts in recirculation aquaculture systems (RAS) is growing, and novel production protocols using continuous light in RAS are being implemented in the industry. In the present study, Atlantic Salmon parr were exposed to either a traditional protocol (short-day winter signal [12:12 L:D] for 6 weeks) or to continuous light. Both photoperiods were applied in freshwater (FW) and brackish water RAS. Salmon from all treatments were transferred to seawater pens at 200 and 600 g and grown until slaughter size. A control group was smoltified with a 6-week short-day winter signal and kept in FW until sea transfer at 100 g. Continuous light gave a higher growth rate in RAS but reduced feed intake and growth and increased feed conversion ratio during the first 8 weeks in seawater. However, at slaughter, fish exposed to continuous light was bigger than fish given a winter signal because of the higher growth rate in RAS. Slaughter weight was lowest in fish transferred to sea at 600 g, despite having the highest day-degree sum during their life span. The best performing group was the control group transferred at 100 g. All treatments handled transfer to seawater and survival and maturation were not affected by the treatments in RAS. The immune status was examined with a multigene expression assay on BioMark HD platform from parr stage to 5–7 months after seawater transfer. Overall, there was no significant effect of photoperiod or salinity on the expression of the selected immune genes. In sum, the results from this study indicate that using continuous light in RAS may have negative effects on performance shortly after transfer in fish transferred to sea at 200 g, whereas at 600 g, all treatments had reduced growth after transfer irrespective of treatment in RAS.publishedVersio

Stress Impairs Skin Barrier Function and Induces α2-3 Linked N-Acetylneuraminic Acid and Core 1 O-Glycans on Skin Mucins in Atlantic Salmon, Salmo salar

The skin barrier consists of mucus, primarily comprising highly glycosylated mucins, and the epithelium. Host mucin glycosylation governs interactions with pathogens and stress is associated with impaired epithelial barrier function. We characterized Atlantic salmon skin barrier function during chronic stress (high density) and mucin O-glycosylation changes in response to acute and chronic stress. Fish held at low (LD: 14–30 kg/m3) and high densities (HD: 50-80 kg/m3) were subjected to acute stress 24 h before sampling at 17 and 21 weeks after start of the experiment. Blood parameters indicated primary and secondary stress responses at both sampling points. At the second sampling, skin barrier function towards molecules was reduced in the HD compared to the LD group (Papp mannitol; p < 0.01). Liquid chromatography–mass spectrometry revealed 81 O-glycan structures from the skin. Fish subjected to both chronic and acute stress had an increased proportion of large O-glycan structures. Overall, four of the O-glycan changes have potential as indicators of stress, especially for the combined chronic and acute stress. Stress thus impairs skin barrier function and induces glycosylation changes, which have potential to both affect interactions with pathogens and serve as stress indicators. View Full-TextpublishedVersio

ANALISIS KEMAMPUAN BERFIKIR ALJABAR DI KELAS VII SMP NEGERI 1 KRANGKENG KABUPATEN INDRAMAYU (Studi Survei di Kelas VII Tahun Akademik 2012/2013)

Setiati Rahayu, 2013. Analisis Kemampuan Berfikir Aljabar di Kelas VII di SMP Negeri 1 Krangkeng Kab. Indramayu (Studi Survei di Kelas VII Tahun Akademik 2012/2013) Untuk mengukur kemampuan berfikir aljabar seorang siswa diperlukan beberapa indikator. Terdapat beberapa indikator untuk memahami aljabar diantaranya memahami pengertian koefisien variabel suku sejenis, kemampuan melakuakan operasi hitung, kemampuan mengggunakan simbol matematika, kemampuan menggunakan bahasa sehari-hari, kemampuan menyederhanakan operasi aljabar, kemampuan menyatakan berbagai hubungan, kemampuan menggunakan diagram alur dan memahami konsep aljabar invers. Tujuan dalam penelitian ini untuk menganalisis kemampuan berfikir aljabar di kelas VII yang ditinjau dari operasi aljabar, penggunaan aljabar, masalah aljabar, dan pemahaman konsep aljabar saat menjawab soal-soal aljabar. Kemampuan siswa dalam memahami aljabar merupakan suatu kondisi yang terdapat dalam sekolah SMP tersebut. Aljabar adalah suatu cabang ilmu matematika yang menggunakan tandatanda dan huruf-huruf yang mewakili angka-angka. Banyaknya indikator yang menjadi indikator kemampuan aljabar, maka akan ada beberapa indikator yang akan menjadi komponen utama dalam kemampuan aljabar. Untuk mengetahui kemampuan siswa dalam memahami aljabar, tidak perlu semua indikator pada\ud materi aljabar diujikan dalam tes. Mengetahui sangat pentingnya komponen utama dalam materi aljabar untuk mengukur kemampuan berfikir aljabar seorang siswa maka peneliti mencoba menganalisis kemampuan berfikir aljabar siswa kelas VII di SMPN 1 Krangkeng. Teknik pengumpulan data yang digunakan dalam penelitian ini adalah tes. Populasi dalam penelitian ini adalah Kelas VII yang berjumlah (160 siswa). Sampel diambil dari kelas VIIB cluster random sampling. Untuk uji coba dilakukan di kelas VIIA yang berjumlah 32. Dari hasil penelitian diperoleh hasil sebagai berikut: 1) Aljabar di SMP N 1 Krangkeng cukup baik hal ini ditunjukan dengan nilai rata-rata 75. 2) Indikator kemampuan berfikir aljabar secara mekanisme dan indikator Kemampuan terbesar yang dicapai oleh siswa kelas VII SMP Negeri 1 Krangkeng tahun ajaran 2012/2013 dalam memahami aljabar adalah pada pengertian koefisien, variabel, konstanta, faktor, suku sejenis adalah sebesar 89.58% dan kemampuan yang kurang dikuasai oleh siswa kelas VII SMP Negeri 1 Krangkeng tahun ajaran 2012/2013 dalam memahami aljabar adalah memahami invers adalah sebesar 85.94%. 3) Dari delapan indicator kemampuan berfikir aljabar ada tiga komponen yang dominan yaitu menggunakan diagram alur, pengertian koefisien variable konstanta, faktor suku sejenis, dan menyederhanakan operasi aljaba

Mixing and scale affect moving bed biofilm reactor (MBBR) performance

acceptedVersio

The effect of AQUI-S on nitrogen compound removal efficiency in recirculating aquaculture system (RAS)

AQUI-S (AQUI-S® New Zealand Ltd., Lower Hutt, New Zealand) is a water dispersible liquid anaesthetic that is currently approved in Norway for sedation and anesthesia of Atlantic salmon (Salmo salar L.) and rainbow trout (Oncorhynchus mykiss) prior and during handling events and during live fish transport. Its active ingredient is isoeugenol; 540 mg/ml. It is used both in flow-through and recirculating aquaculture systems (RAS). However, the potential effects of AQUI-S on the biological component of the water treatment and the possible accumulation within RAS water have not been closely investigated. This project aims to look into the bioreactor efficiency of nitrogen compound removal and AQUI-S stability and potential accumulation within RAS water. The initial concentration of AQUI-S in the RAS water was 5 ml/m3 total system volume, corresponding to 2,7 mg isoeugenol L-1. This represents the maximum load of Aqui-S that theoretically will be added to a RAS; usually only a few tanks in the circuit will be medicated at once, not the entire system. Six hours after addition of AQUI-S, 86-87% of the isoeugenol was degraded or converted although the total water exchange within RAS was very low (6.6 %). It is therefore anticipated that in commercial RAS where the level of total daily water exchange might be higher, the depletion of AQUI-S from water would occur even faster. The water quality and the removal of the TAN and NO2-N were moderately affected, particularly during first 12h of the experiment. One of the reasons for the disturbance of the bioreactor function could be foam formation that was visible prior and in all three chambers of the MBBR within 30 minutes after addition of the AQUI-S. Consequently the difficulty in the mixing and the drop in the oxygen saturation within MBBR could have affected proper operation of the bioreactor. In addition, the low and decreasing concentration of nitrogenous compounds within the system (lack of feeding and fish) is not favourable for the nitrification process within bioreactor. However, it is important to stress that certain amount of nitrogenous compounds was removed at all times. The increase in concentration of TAN and NO2-N was significant; however concentrations were within recommended values issued by Norwegian Food Safety Authorities at all times during the experiment. This conclusion will, however, depend on the initial load of the system. Hence, it is recommended that before AQUI-S use, the TAN levels should not be above 1 mg/l (at pH 7.4 or less), to allow some reduction in removal efficiency and still be within legislation regarding TAN concentration. The removal efficiency of nitrogenous compounds oscillated during first 12 h of experiment but was not significantly affected by addition of AQUI-S. After 12 h, a steady increase in removal efficiency was recorded for TAN and NO2-N, respectively. This conclusion will, however, depend on the initial load of the system. Hence, it is recommended that before AQUI-S use, the TAN levels should not be above 1 mg/l (at pH 7.4 or less), to allow some reduction in removal efficiency and still be within legislation regarding TAN concentration. The removal efficiency of nitrogenous compounds oscillated during first 12 h of experiment but was not significantly affected by addition of AQUI-S. After 12 h, a steady increase in removal efficiency was recorded for TAN and NO2-N, respectively. • The study indicates that Aqui-S is readily degraded by RAS bioreactors, minimizing the risk of isoeugenol accumulating following sequential medication of fish tanks in the RAS • AQUI-S used at doses recommended for sedation is not likely to have serious effects on bioreactor within 48 hours following its use in RAS • Increased foaming in the moving bed bioreactor during the first hours following Aqui-S administration might cause or contribute to a transient reduction in TAN and NO2 –N removal efficiency

Hydrodynamics of octagonal culture tanks with Cornell-type dual-drain system

publishedVersio

Influence of inlet and outlet placement on the hydrodynamics of culture tanks for Atlantic salmon

The salmon farming industry has recently shifted to larger culture tanks with greater water flows to optimize the land-based production, but tanks approaching 1000 m3 in volume create challenging hydrodynamics. This paper presents a computational study of four combinations of inlet and outlet designs of a commercial land-based aquaculture tank. Windows-based OpenFOAM solvers are used to solve the conservation equations for tank hydrodynamics with an implicit unsteady second-order Eulerian (finite volume) technique on unstructured hybrid meshes. The model is validated by the velocity measurements at discrete locations in the tank using acoustic doppler velocimetry. To understand the dispersion of biosolids in the tank, 500 particles with a uniform size of 200 µm are tracked in the Lagrangian frame. While the tank's Reynolds number varies between 2E6 - 3.5E6 depending on the flow exchange rate, the local Reynolds number at the inlet pipe is about 2E5 which discovers the drag-crisis phenomenon. The effect of inlet and outlet placement on the velocity, vorticity and turbulence is addressed. The existing tank design could be improved using the bottom-drain and corner-inlet options, which strengthens rotational flow with better uniformity. Such design change is also proved to provide better particle removal and thus ensure the improved self-cleaning ability of the tank.publishedVersio

Water velocity in commercial RAS culture tanks for Atlantic salmon smolt production

publishedVersio

Influence of inlet and outlet placement on the hydrodynamics of culture tanks for Atlantic salmon

The salmon farming industry has recently shifted to larger culture tanks with greater water flows to optimize the land-based production, but tanks approaching 1000 m3 in volume create challenging hydrodynamics. This paper presents a computational study of four combinations of inlet and outlet designs of a commercial land-based aquaculture tank. Windows-based OpenFOAM solvers are used to solve the conservation equations for tank hydrodynamics with an implicit unsteady second-order Eulerian (finite volume) technique on unstructured hybrid meshes. The model is validated by the velocity measurements at discrete locations in the tank using acoustic doppler velocimetry. To understand the dispersion of biosolids in the tank, 500 particles with a uniform size of 200 µm are tracked in the Lagrangian frame. While the tank's Reynolds number varies between 2E6 - 3.5E6 depending on the flow exchange rate, the local Reynolds number at the inlet pipe is about 2E5 which discovers the drag-crisis phenomenon. The effect of inlet and outlet placement on the velocity, vorticity and turbulence is addressed. The existing tank design could be improved using the bottom-drain and corner-inlet options, which strengthens rotational flow with better uniformity. Such design change is also proved to provide better particle removal and thus ensure the improved self-cleaning ability of the tank