Location: Cool and Cold Water Aquaculture ResearchTitle: Comparison of hydraulics and particle removal efficiencies in a mixed cell raceway and burrows pond rearing system Author
|Stockton, Kelly - Idaho Cooperative Fish & Wildlife|
|Moffitt, Christine - Us Geological Survey (USGS)|
|Watten, Barnaby - Us Geological Survey (USGS)|
|Vinci, Brian - Freshwater Institute|
Submitted to: Aquacultural Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/18/2016
Publication Date: 5/24/2016
Citation: Stockton, K.A., Moffitt, C.M., Watten, B.J., Vinci, B.J. 2016. Comparison of hydraulics and particle removal efficiencies in a mixed cell raceway and burrows pond rearing system. Aquacultural Engineering. 74:52-61. doi: 10.1016/j.aquaeng.2016.04.005.
Interpretive Summary: Two Burrows ponds were renovated into two mixed cell raceway systems at the Dworshak National Fish Hatchery, ID, in an effort to identify technologies to improve solids removal. The two mixed cell raceways used the same foot print as the former Burrows ponds, but each mixed cell raceway had four counter rotating cells with appropriate drains and inlet water jets. The mixed cell raceway provided higher mean velocities and a more uniform velocity distribution than did the Burrows pond. The drains and velocity gradients of the mixed cell raceway provided highly efficient particle removal compared to the Burrows pond. Finally, rainbow trout reared in the mixed cell raceways were well dispersed throughout the variable velocity environment and validated the concept's potential use as a hatchery production system. However, further testing in hatchery production trials is recommended to evaluate fish growth and physiology.
Technical Abstract: We compared the hydrodynamics of replicate experimental mixed cell and replicate standard Burrows pond rearing systems at the Dworshak National Fish Hatchery, ID, in an effort to identify methods for improved solids removal. We measured and compared the hydraulic residence time, particle removal efficiency, and measures of velocity using several tools. Computational fluid dynamics was used first to characterize hydraulics in the proposed retrofit that included removal of the traditional Burrows pond dividing wall and establishment of four counter rotating cells with appropriate drains and inlet water jets. Hydraulic residence time was subsequently established in the four full scale test tanks using measures of conductivity of a salt tracer introduced into the systems both with and without fish present. Vertical and horizontal velocities were also measured with acoustic Doppler velocimetry in transects across each of the rearing systems. Finally, we introduced ABS sinking beads that simulated fish solids then followed the kinetics of their removal via the drains to establish relative purge rates. The mixed cell raceway provided higher mean velocities and a more uniform velocity distribution than did the Burrows pond. Vectors revealed well-defined, counter-rotating cells in the mixed cell raceway, and were likely contributing factors in achieving a relatively high particle removal efficiency - 88.6% versus 8.0% during the test period. We speculate retrofits of rearing ponds to mixed cell systems will improve both the rearing environments for the fish and solids removal, improving the efficiency and bio-security of fish culture. We recommend further testing in hatchery production trials to evaluate fish physiology and growth.