1-s2.0-S0044848618X00155-cov150h.gif New publication on aerobic bioreactor technology

Our Aquaculture Centre of Excellence researchers, Dr. Zied Khiari, Soba, Kaluthota, and Dr. Nick Savidov have recently published the article, "Aerobic bioconversion of aquaculture solid waste into liquid fertilizer: Effects of bioprocess parameters on kinetics of nitrogen mineralization", in the February 2019 edition of Aquaculture.


 

Aquaponics is the integrated culture of fish, plants and beneficial microorganisms grown in a soilless environment. Fish and plants grow in one ecosystem, eliminating the waste they separately produce by turning it into something of use. The waste created by the fish becomes a food source for beneficial microorganisms, which convert into mineral nutrients for the plants. The plants act as a natural filter, cleaning the water for the fish. It’s essentially zero-waste agriculture.

Aquaponics: Our integrated food production systems

Nick Savidov and Penny Takahashi-27.jpg
Dr. Nick Savidov, Senior Research Scientist and Penny Takahashi, Greenhouse Technician

Aquaponics research is carried out at ACE year-round using specially designed indoor aquaponics models equipped with state-of-the-art LED lights. The year-round attached greenhouse, which was significantly upgraded in 2018, is used to demonstrate the technology to public and industry. A variety of vegetables, herbs and water plants are selected based primarily on their market demand. Crops are also selected for their:

  • value
  • yields
  • quality
  • organoleptics
  • water filtration capacity

Throughout the process, crops are tested for their adaptability to the aquaponics system.

Indoor systems

Our aquaponics research is primarily conducted indoors, which requires complete lighting to be supplied by artificial means. Conventional grow light technology, such as HID lamps, has been replaced with more modern options like LEDs. These technologies are all energy efficient and have a long life compared to common HID lamps.

The indoor systems include over 60 specially developed recirculating oxygenated aquaponics modules, which include 12 larger modules (2,000 L, based on UVI design), 9 Deep Water Culture modules (700L, designed by Dr. Nick Savidov) and 41 vertical Nutrient Film modules (80 L, designed by Dr. Nick Savidov and Clay Boyes).

Veggies-1.jpg
Vertical aquaponics

The modules consist of:

  • fish tanks
  • waste filtration and sedimentation tanks
  • biofiltration tanks (Moving Bed Biofilm Reactors (MBBR), biochar trickling filters)
  • Deep Water Culture (DWC), Nutrient Film (NFT) and substrate drip-irrigated beds

Water recirculation in the system works by hydrostatic pressure. Once the tanks are filled, the water levels remain the same due to a constant pump flow rate and the gravity flow from differing tank heights. The water is pumped from the water collecting tank to the fish tanks and then flows by gravity to the waste separating tank, biofiltration tank, water collecting tank, and plant troughs before being pumped back to the fish tanks.sedimentation tank, MBBR tank, plant troughs and water collecting tank before being pumped back to the fish tanks.

Plants are grown on floating rafts placed on plant trays within the recirculating system. LED lights are suspended 35 centimetres above these floating rafts. Nutrients are provided either from fish effluent or organic liquid fertilizers produced in specially designed aerobic bioreactors.

Concentrated oxygen is exchanged through specially designed oxygen saturators.

 

Greenhouse systems

 

The newly retrofitted aquaponics greenhouse operates year round. The modification included improved cooling, powerful 1000 W lights and more efficient air circulation. Multiple substrate and DWC plant beds, and vertical towers, located in a 10 by 30 metre greenhouse, utilize a side-stream flow from the adjacent tilapia production facility. During the spring, summer, fall, and winter this greenhouse produces a diverse crop mix using the drip irrigation, DWC, NFT and vertical farming technique.

Since the water used to grow the greenhouse plants is recirculated back to the fish facility for reuse, pests can be managed through biocontrol – eliminating the need for herbicides or pesticides. As a last resort, organically approved sprays such as soap or living bacteria-based pesticides may be used.

Our research

Our focus on developing an intensive water recirculation aquaculture operation naturally evolved into our aquaponics research. This research is multifaceted and has benefitted from the funding provided by NSERC.

Our constant research into new systems and new crops provides unique learning experiences for Lethbridge College students as well as the many visitors who tour the research areas of ACE. Consider booking your tour today.

Aerobic bioreactors

In order to produce nutrient solutions from fish solid waste (FSW), a waste treatment system was designed and constructed between September 2015-February 2016, which included six aerobic bioreactors and an Argus Control System. The facility was commissioned on March 7 – 11, 2016.

bioreactors.png
Aerobic bioreactor facility for FSW conversion into nutrient solutions at ACE

 

The aerobic bioreactor facility was based on the design developed by Dr. Nick Savidov between 2004-2011 at CDC South and CDC North research stations, Alberta Agriculture. This allowed for development of Canada's first, zero-waste food production system.

 

 

 

 

Development of nano- and microfiltration system based on biochar

Biochar Filter.jpg
Pilot-scale biochar trickling filter

Biochar as a biofiltration and plant growing medium was initiated by Dr. Nick Savidov in Alberta in collaboration with Alberta Research Council in 2004. In 2018, ACE received Alberta Innovates Campus Alberta Small Business Engagement Program (CASBE) and NSERC Engage Program grants. One pilot-scale filter and 3 smaller biochar filters were built.

The study, which also included scientist Dr. Khiari, demonstrated a unique capacity of biochar to remove very small particles of solid material from 0.1 to 30 micron (see the picture below). This makes biochar an ideal material for Phase II water polishing step after drum filter and sedimentation tanks, which can only remove particles larger then 30 micron. As a result, the Total Suspended Solids (TSS) level in filtered water drops below 2 ppm. Biochar is a very porous material, which can accommodate a variety of beneficial microorganism and enhance biofiltration capacity of recirculated aquaculture systems as a whole. The biological activity results in self-regenerating ability of trickling filters based on biochar, so biochar can be reused indefinitely. The introduction of this new affordable filtration tool into aquaculture practice can drastically improve capacity of water regeneration systems in aquaculture and aquaponics industry.

Seedling production

Conventionally, we’ve used used biochar, coconut coir, rockwool and vermiculite as seeding media mixes. These mixes allow for good root development without the need for additional fertilization, producing exceptional seedlings to use in a variety of aquaponics systems.

Seed production

Through an Organic Alberta grant, we conducted trials to produce seeds from aquaponics lettuce crops in an attempt to improve the cultivars for hydroponic production. Seeds were saved from two varieties of lettuce grown in our DWC systems. These seeds were tested for viability and re-grown, creating a sustainable seed production. The excess seeds are now made available to other aquaponics growers in the region.

Cold water aquaponics research

There has been limited research conducted on the use of cold water fish species in aquaponics plant production, primarily due to the sub-optimal water temperatures for producing tropical vegetables. The growth rates of hydroponic vegetables slow down when the culture water is chilled to temperatures ideal for fish species such as:

  • trout
  • salmon
  • char

Producers of these high-value fish are faced with the task of identifying a crop mix that grows well under low temperatures while generating enough income to sustain the production system.

At ACE, we started cold water aquaponics using rainbow trout in 2015. Numerous experiments have been conducted to date that demonstrate the technical feasibility of trout aquaponics in Canada.

New fish species

Barramundi was recently added to the approved fish species list for aquaculture production in Alberta. However, before the fish are released to Alberta producers, they have to go through a quarantine period where the fry are evaluated for the risk of disease introduction. ACE was selected as the only Alberta facility capable of this quarantine.

Barramundi is a high-value fish species that may provide aquaponics producers with a new product and improve the economic potential of existing aquaponics facilities. Ongoing production trials will include identifying crops that are best suited for production in the barramundi water.