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Algae Cultivation

Algae Cultivation via a Novel Photobioreactor and Harvest Apparatus for Sustainable Aquaculture

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Algae can be used as a replacement for fish oil and fishmeal, which aquaculture relies heavily on as a source of protein and fatty acids in formulated fish foods. In fact, microalgae are the primary producers of highly unsaturated fatty acids (HUFA) for the entire global food chain, marine and terrestrial segments combined. Because algae cultivation can make up 30-40% of a hatchery’s operating expenses, improvements in algae production can lead to significant savings and a better bottom line for the business. Due to the rising costs of these wild ingredients and their finite supply, new alternatives are needed.

Microalgae cultivation has long been an integral part of hatchery operations for the production of finfish, shellfish, and other aquaculture species. Marine consumers of microalgae include: oysters (all developmental stages), abalone, sea urchin, conch, penaeid shrimp larvae, sea monkeys, and zooplanktonic live prey (e.g. rotifers), which are cultivated as food for finfish larvae.

Additionally, algae have shown potential as supplementary ingredients in formulated feeds as a natural source of vitamins, amino acids, and the pigment molecule astaxanthin, which is responsible for the pink coloration of salmonid flesh.

“Algae can also be used as a replacement for fish oil and fishmeal, which aquaculture relies heavily on as a source of protein and fatty acids in formulated fish foods. Due to the rising costs of these wild ingredients and their finite supply, new alternatives are needed.”

While terrestrial crops such as wheat, corn, and soy can be substituted for a portion of the marine-derived ingredients, these crops lack the highly unsaturated fatty acids (HUFA) (e.g. DHA, EPA, and AA) that fish oil and fish meal provide.

Algae Cultivation

 

Figure 1: A full-scale (55,000-L) TriPARTM system, growing Haematococcus pluvialis at our research site in San Diego, CA. The TriPARTM provides several advantages to algae growers including: 1) contamination resistance for over 4 months 2) reduced need for dewatering by special harvest apparatus 3) eliminated need for temperature control 4) lower labor requirements via process automation 5) higher productivity via biofilm resistance, 6) reduced dependency on concentrated carbon dioxide (CO2) and 7) the modular assembly of the reactor cage makes for easy system expansion.

Microalgae, however, can provide these HUFA’s as well as protein. In fact, microalgae are the primary producers of HUFA for the entire global food chain, marine and terrestrial segments combined.

Given the key role that algae cultivation plays in aquaculture and its rising potential, Pure Biomass Inc. is focused on delivering state-of-theart, yet affordable algae cultivation systems to help aquafarmers improve the quality, reliability, and productivity of their algae production process.

Because algae cultivation can make up 30-40% of a hatchery’s operating expenses, improvements in algae production can lead to significant savings and a better bottom line for the business.

The Triangular Prism Algae Reactor

The centerpiece of the Pure Biomass algae production platform is our newly developed TriPARTM (Triangular Prism Algae Reactor) intended for large-scale, sustainable algae production. The TriPAR is a closed photobioreactor containing 8,500 L within a space of ~10 m2 (6.7’ x 16’) by 6.’ high.

The inner reactor body is formed from a large plastic bag, which is surrounded by an aluminum support cage in the shape of a long, triangular prism. Inside the reactor, a robotic harvest apparatus allows for the daily removal of concentrated biomass while maintaining culture sterility.

“Operation of the system is completely automated, including media charging, pH control, nutrient feeding, and biomass harvest.”

The unit can be operated as either a semi-continuous or fully-continuous system. If more capacity is required in the future, the same reactor can be linearly expanded in 4 ft. sections up to a maximum volume of 55,000-L (104’ long).

Benefits of the TriPARTM include: minimal (or no) requirement for concentrated CO2 supplementation, no requirement for a surrounding greenhouse, reduced energy loads for heating and cooling, and significantly improved water conservation compared to traditional reactors, all while maintaining culture purity and high productivity on a modest areal footprint.

Algae Cultivation

To achieve these benefits, the TriPARTM leverages several technological features:

1) The large volume of the culture allows for a high efficiency of CO2 capture while requiring a minimum amount of energy to drive mass transfer.

2) The reactor geometry is designed so that the air bubbles flow continuously along the inner walls, constantly mixing the culture and scouring the surface free of biofilm. This allows for unfettered light penetration into the reactor, and largely removes the reservoir for contamination that a biofilm provides.

3) The style of mixing generated by the rising bubbles closely mimics optimal algae growth conditions found in nature, reproducing the cyclical pattern of light exposure that maximizes photosynthetic efficiency.

4) By taking advantage of gravity, upon turning off the air, the harvest apparatus, which is completely novel to photo-bioreactors, allows for the removal of settled biomass without compromising sterility. The potential result is a 20x reduction in water consumption associated with harvest and refill compared to existing technology.

5) The plastic bag used for process containment lowers the frequency of contamination events leading to better crop purity and more process uptime. In the event that a contamination does occur, the downtime required for process cleanout is greatly reduced by the ability to simply install a new culture bag, which also reduces the likelihood of a repeat contamination due to inadequate cleaning.

In addition to our full-scale TriPARTM reactor, Pure Biomass also provides the seed train equipment needed for inoculum expansion. These include 25-L hanging bags, 250-L reactor cages, and 1350-L reactor cages. Together these units allow for clean seed expansion from frozen seed stocks all the way to full-scale inoculation.

To the hatchery industry, both algae quality and quantity are key factors. The quantity of algae produced, which depends on both the volume of the cultivation equipment and the productivity of the process (cell dry weight/L/day), is important, because algae cultivation is such a large part of a hatchery’s operating expenses.

Figure 2: Pure Biomass provides algae cultivation technology that focuses on affordable bio-secure solutions. By following our comprehensive standard operating procedures on sterile technique and culture transfer, you will be able to maintain high value, contamination resistant algae cultures, and produce them at the right scale for your operation.

 

Figure 2: Pure Biomass provides algae cultivation technology that focuses on affordable bio-secure solutions. By following our comprehensive standard operating procedures on sterile
technique and culture transfer, you will be able to maintain high value, contamination resistant algae cultures, and produce them at the right scale for your operation.

Algae quality is an important attribute due to the sensitivity of animal development to the balance of nutrients supplied by its diet. Ensuring proper animal nutrition is often so important as to warrant the cultivation of 3-5 different algal species in a single hatchery.

This is done in order to provide the right blend of nutrients during each stage of an animal’s developmental cycle. Because the TriPARTM is a closed system, a hatchery is able to achieve high culture purity by excluding unwanted algal strains found in the local environment.

In addition, the use of process automation and instrumentation for pH control, nutrient delivery, and batch cycle management ensure reliable, high productivity cultivations and that process conditions are maintained at the correct values to maximize the nutritional value of each algae strain.

“Due to the technical requirements needed for a hatchery to simultaneously produce multiple algal strains, the use of commercial algae concentrates has become a popular alternative.”

While these products do provide a way for hatcheries to more closely dial in their optimum feeding ratios, the efficacy of these products have been shown to be inferior to the efficacy of fresh algae cultures.

Furthermore, at prices of $400-600/kg dry weight, algae concentrates can be significantly more expensive than algae cultivated in-house $150-400/ kg dry weight. This cost for in-house algae cultivation is based on the assumption of a small cultivation operation (~25 m2 ); however, larger algae cultivation operation with the TriPARTM system can bring down costs to <$30/kg dry weight.

Pure Biomass believes that our TriPARTM system offers a good way for hatcheries of all sizes to produce their own, high-quality, live algae feeds using a robust production process. Furthermore, the TriPARTM system is easily scalable so hatcheries can grow their algae cultivation operations to the sizes where dramatic cost savings on algae feeds are possible.

For more information visit: http://www.purebiomass.org/

WAS
CARGILL
Cargill Empyreal75
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ISFNF
ISFNF
GLOBAL LEADERS

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