Compressed air applications in Aquaculture
Sea Pen Oxygenation (SPO)
Oxygen is crucial for healthy, growing fish in aquaculture. However, several factors - such as warm water temperatures, thermal stratification, and certain algae blooms - can reduce oxygen levels in net pens. Farmers must proactively monitor and manage these levels carefully, as prolonged exposure to less-than-ideal or fluctuating oxygen conditions can significantly stress the fish, weaken their immune system, and compromise growth efficiency. This can ultimately lead to increased operational costs by raising the Feed Conversion Ratio (FCR). If oxygen levels drop too low, farmers may even need to temporarily suspend feeding to protect their stock.
Sea Pen Oxygenation (SPO) is a key technique for rapidly boosting oxygen saturation in net pens during acute low-oxygen events, such as severe algae blooms. In these emergencies, SPO provides critical life support, ensuring fish receive the oxygen they need to survive and thrive. Beyond emergency use, some farms choose to continuously employ SPO to maintain optimal oxygen conditions, an approach that shows significant advantages, including improved overall fish health, enhanced resilience to disease, and optimised FCRs.
Onsite oxygen production using oxygen generators is the widely favored method for creating the concentrated oxygen required for SPO systems. To achieve this, compressed air is fed into an adsorption vessel containing a molecular sieve (typically made of Zeolite). A molecular separation process takes place: nitrogen molecules are strongly adsorbed by the sieve material, while the oxygen molecules, having a weaker attraction, are able to pass through the vessel largely unadsorbed. This results in the generation of a highly concentrated oxygen gas. Once produced, the oxygen is then injected into the net pens through micro- or nano- bubble diffusers.
The entire adsorption process relies on a dependable supply of compressed air at the correct ISO 8573-1:2010 quality standard, to ensure continuous and efficient oxygen generation. Crucially, the performance and lifespan of the molecular sieve is extremely sensitive to contaminants. For this reason, compressed air treatment is essential to effectively remove moisture and oil from the compressed air.
KAESER solutions for Sea Pen Oxygenation (SPO)
KAESER compressed air systems reliably deliver the high-quality feed air essential for on-site oxygen production using oxygen generators, critical for Sea Pen Oxygenation (SPO).
Whether the requirement is for a stationary or a portable compressor, powered by electric motor or combustion engine, and delivering standard or low pressure air, this can be achieved through KAESER’s comprehensive portfolio of robust, reliable, and energy-efficient rotary screw compressors.
Furthermore, air quality is assured by KAESER’s complete compressed air treatment portfolio - including centrifugal separators, dryers, filters, and activated carbon adsorbers. These components can be selected to meet both the generator manufacturer’s specifications and the stringent ISO 8573-1:2010 standards.
FAQs
Sea Pen Oxygenation (SPO) provides high-efficiency dissolved oxygen (DO) boosting by injecting pure oxygen (typically 90-95% purity), making its performance entirely independent of ambient water conditions.
In contrast, Sea Pen Aeration (SPA) is entirely dependent on ambient conditions. It achieves oxygenation mainly by circulating and drawing up existing oxygenated water from lower depths. If the underlying water is not already oxygen-rich, or if atmospheric DO transfer is insufficient, SPA cannot effectively increase DO. In addition, the maximum achievable DO concentration with SPA is limited by the saturation point attainable by ambient air. This ceiling is significantly lower than SPO’s capability of supersaturation and may be insufficient for high-density or stressed stock.
Therefore, SPO is ideal for farms requiring rapid attainment of set-point DO levels. Its independent capability makes it essential for guaranteeing precise DO saturation, effectively managing high-density stocking, and quickly correcting critical low DO events caused by factors like severe algae blooms.
Ultimately, the final choice between SPO and SPA depends on a site's specific environmental conditions, the required oxygen saturation level, and the necessary speed of correction.
The type of oxygen generators that we have discussed utilise a separation process based on molecular sieves. The core component of these systems is the molecular sieve material - typically zeolite - which is highly sensitive to oil and moisture. In order to keep the molecular sieve in optimum condition and ensure the long-term reliability and efficiency of the oxygen production process, the compressed air quality must be maintained at a very high standard.
These oxygen generators typically require compressed air to meet the strict specifications of the ISO 8573-1:2010 [1.4.1] standard. This classification sets strict limits on particulates (Class 1), water (Class 4), and total oil (Class 1).
A Sea Pen Oxygenation (SPO) system is designed primarily as a life-support tool. Its function is to rapidly increase the dissolved oxygen (DO) concentration in the water column to support fish health and prevent mortality during low-DO events. These low-oxygen events may be caused by various factors, including the high oxygen consumption from the respiration or decay of large algal blooms.
The SPO system achieves this by efficiently dissolving pure oxygen directly into the net pens. Crucially, it does not generate the necessary physical water movement (circulation or upwelling) required to mitigate, eliminate, or repel any types of algae. Therefore, while it protects the fish from the severe effects of hypoxia (lack of oxygen) caused by a bloom, the SPO system is not a physical mitigation tool against the algae itself. This means it does not protect the fish from other types of algae which can harm the fish by toxicity or structural damage.
Yes. The MOBILAIR M 450LP has been specifically developed to meet the requirements of aquaculture applications like on-site oxygen production.
This low-pressure diesel-driven portable screw compressor can be fitted with a 10 kVA generator. The M 450LP can then be used as an autonomous compressed air station, capable of powering a refrigeration dryer. This allows for the installation of an activated carbon adsorber that filters out the hydrocarbons in the form of aerosols; this is necessary to reach Total Oil Class 1, which contributes significantly to the longevity of the molecular sieve.
Ideal for remote locations where an electrical power source is not available, the M 450LP delivers technically oil-free compressed air for applications demanding the highest compressed air quality standards.
