1. TANK OPTIMIZATION FOR IMPROVED
HYDRODYNAMICS IN AQUACULTURE AND AQUAPONICS
Michael Galloway1 and Shaun M. Gill2
1UNE Aquaculture and Aquarium Sciences ‘15, Pratt & Whitney Marine Fellow in Aquaculture Engineering
2Marine Science Center, University of New England
Background
The aquaculture industry is a dynamic field which is growing at a rapid rate. This growth is driven by a combination of static or declining catches from most traditional fisheries, declines in stocks of
many commercially caught fish species, and the increased need for marine protein as a result of global population growth. Consequently, aquaculture engineering is being turned to for solutions that
allow this growth to be possible. Aquaculture engineering requires great knowledge breadth, covering traditional general engineering specialties such as mechanical, environmental, materials
technology, but also solid understandings of biology, chemistry, and ecology. Understanding how these specialties interact and complements each other allows one to engineer solutions that
efficiently utilize resources, such as water, land, feed, broodstock and seed, to their fullest potential. Balancing engineering and biological interactions ensures quality aquaculture systems with hearty
products required for our expanding society. This project focuses on engineering designs that drive aquaculture and aquaponics tank hydrodynamics in order to maximize a tank’s self cleaning
capabilities. Effective self cleaning is desirable because quickly collecting and removing settable solids improves water quality, system function, and overall economy. In the case of aquaponics the
solids are further processed via additional system engineering to provide valuable plant nutrition.
Trout Room Internship Pratt & Whitney Fellowship
Introduction
The University of New England is enthralled in new and groundbreaking
opportunities in sustainability and human food systems. A pivotal place for new
growth and development has been the Marine Science Center (MSC), where
students can be immersed in new hands-on learning initiatives and allowed to
explore their passions. Through collaborations between the Marine Sciences
and Biology departments, one project that was made possible was the
repurposing of a 10,000 gallon pool for the growout of Kamloops variety of
Rainbow Trout (Oncorhynchus mykiss) obtained from Shy Beaver Trout Hatchery
in Hollis, Maine. In the Spring of 2015, I held a UNE CAS internship focused on
managing the Trout project, inheriting a quickly changing system that taught me
the intricacies of managing new and evolving system processes.
Design Lessons Learned
Undersized filtration and high stocking densities lead to high waste production
creating immediate and significant challenges for managing water quality and
operating the system efficiently. Upgrading filtration components is a logical
and simple solution, but expensive. But even the best filtration, is only as
good as the systems ability to concentrate and collect settleable solids.
Hence, identifying improvements and creating prototypes for improving
system hydrodynamics were the immediate steps towards resolving the tank's
self cleaning challenges.
Challenges
The trout were housed in a recirculating system initially designed for holding
sea turtles. As a repurposed system, the trout’s high stocking density
overwhelmed the system’s capabilities and forcing new solutions to be
identified. The system was run as both a recirculating and flow through to
control parameters such as temperature shifts, open-environment
interactions, and water quality. When operated as a closed-looped,
recirculating aquaculture system (RAS) additional challenges arose due to
shifts in dissolved oxygen (D.O), pH, and Ammonia (Nitrate and Nitrite).
Acknowledgments
I would like to give a special thank you to Pratt & Whitney for funding my fellowship in Aquaculture Engineering; as well as The University of New England College of Arts and Science and CAS Internship
office for allowing me to work alongside a group of amazing people; Asahi- America, Inc. for donating parts; and my mentors and advisors Shaun Gill, Jeri Fox, Adam St. Gelais, Timothy Arienti, and Troy
Thibeau for all of their help across two different internships and throughout this fellowship.
New Prospects
Through the generous support of Pratt & Whitney, I was awarded the 2015
Pratt and Whitney Marine Fellowship in Aquaculture Engineering. My
fellowship focused on evaluating and decommissioning the initial trout
system along with doing research to identify and prototype engineered
solutions for improving aquaculture and aquaponics tank hydrodynamics.
This summer’s work entailed reverse engineering and tested vertical
manifolds to increase flow velocities in the Oncorhynchus mykiss holding
tank. The goal is to provide a successful proof of concept that will provide
grounds for future investments in system infrastructure.
Understanding the Cornell Dual-Drain System
Researchers at Cornell University dedicated to creating sustainable
agricultural and food production processes developed a world-renowned
aquaculture and aquaculture engineering design called the Cornell dual-
drain self cleaning system. They determined that creating uniform flow in a
round tank via vertical manifolds allowed them to collect settleable solids at
a centralized point (i.e. a modified center drain). In addition, the
incorporation of a second side drain would be able to skim off the remaining
solids that float to create better water quality and more efficient use of
resources.
Design Challenges
Fully adopting the Cornell design specifications was a
challenge as the MSC pools are made of concrete and
rectangular in shape. Due to limited information
availability on manifold and center drain design the
vertical manifold prototypes were reverse engineered
based upon literature findings and limited
photographs and opted for a modular design to
promote trial and error. The manifolds are
constructed with threaded fittings that can be
interchanged for experimentation and easily swapped
out in the event of part failure. True-Union Balls
valves donated by Ashai-America allowed for fully
customizable water flow and direction adjustments.
Manifold testing is currently underway to determine
proper nozzle orifice size and number for achieving
rotational velocities that promote self cleaning.
Application to Aquaponics
A Balancing Act
When simultaneously growing fish and plants in the same system, finding a balance
between feed additions, nutrient conversion and overall water quality is crucial, each
relying heavily on proper system engineering and hydrodynamics. Below, preliminary
data from the MSC system shows how a properly functioning system maintains at or
near-zero ammonia levels (red) , which is toxic to fish, even as feed levels (light blue)
are increased, causing subsequent and desirable increases in nitrate levels (purple)
for improved plant nutrition.
As part of the sustainable and Edible Campus initiatives at the University of New
England, a student-centered aquaponics system was developed. Aquaponics is the
fusion of two sustainable practices, hydroponics and aquaculture, in which the waste
of one organism is beneficial to another. Hydroponics is a soilless method of growing
plants in soil-alternative media or fully immersed in water. In comparison to
aquaculture which prioritizes fish as end products, aquaponics prioritizes plants
nourished by strategically collected and re-purposed fish waste. Despite different end
products, all three practices rely upon efficient hydrodynamics and system
engineering for concentrating, collecting, and moving waste. In the case of
aquaculture, the waste is simply collected and removed. Aquaponics, on the other
hand, takes the collected waste and through the process of biological filtration
converts the normally toxic fish waste into bioavailable nutrition for plants.
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Ammonia/NitrateConcentration(mg/L)
AverageWeight/FeedAmount(g)
Day(s) Since First Measurement
Ave Weight (g) Ammonia Feed Nitrate
Future Directions
In the future we hope to see this whole room function as a research and
educational centerpiece. There is much to be learned about rearing fish for
open ocean stocking, and the biology and chemistry of such a complex
system. As a living system we hope to teach students how to interchange
components and understand system operation and appreciate design.
Design specifications call for a 140 gpm of
flow through the manifolds. The modular
nature of this design allows all system
components the ability to rotate and
swing in a 360◦ motion, allowing for almost
infinite flow adjustments. Experiments
employing a rubber ball to measure
surface currents are helping to determine
rotational velocities. Furthermore, the
seawater being used unfiltered and
contains particulate solids. Upon shutting
the system down, the shape and
concentration of the solids deposited on
the tank bottom are used are used as a
proxy for assessing hydrodynamic efficacy.
Rainbow Trout (Oncorhynchus mykiss)
The 10,000 gallon trout holding pool The making s of a new and improved biofilter
With the help of Pentair Aquatic
Ecosystem’s engineering team we
designed a new recirculating system that
capitalizes on the new vertical manifolds.
Not only will the entire system better
collect and capture solids, it disposes of
them faster, yielding better water quality,
maximizing resources, increasing our
biomass and ensures greater quality and
welfare of our fish.
Hydrodynamic and Infrastructure Improvements:
The newly proposed Pentair trout system
with vertical manifolds (arrows) as integral
design components.
A vertical manifold prototype
Adjusting manifold direction
Vertical manifold construction
The new student-centered aquaponics pilot system housed in the Marine Science Center.