The competition for quality water sources has and will continue to force aquaculture facilities to contend with less favorable water quality (WQ) conditions on selected sites. A common, but often poorly addressed water quality issue is nitrogen supersaturation, which can lead to negative health conditions in livestock, such as gas bubble disease. Continuous nitrogen removal can prove costly not just to implement, but also to operate if not chosen properly. Determining the optimal degassing solution for your system is essential to keeping a productive farm. There are six major design criteria to consider when selecting the most efficient and effective technology for each application. These six design criteria are dissolved nitrogen level (DN), dissolved oxygen level (DO), system water flow, reuse percentage, salinity, and power availability. Selecting the best solution using the design matrix of all six factors is sometimes difficult.
Case studies for five Innovasea-designed nitrogen removal systems will be presented, providing a strong basis for selecting one of three industry-standard systems for nitrogen gas management: Vacuum Degassers, Gas Management Towers (GMTs), and Low Head Oxygenators (LHOs). In the first study, LHOs were supplied to a flow-through trout hatchery system with an incoming DN of approximately 105%. The second case study evaluates LHOs for nitrogen removal in a large-scale post-smolt P-RAS salmon system in Iceland. Similarly, the third study assess another large-scale post-smolt P-RAS salmon farm, however, it required GMTs as an alternative to the LHOs supplied in the Icelandic farm case. The final two case studies both assess vacuum degassers supplied as a pre-treatment for a small-scale hatchery in Utah and a saline broodstock system in Mexico. The experience gained from these five case studies has led Innovasea to create a design matrix for selecting nitrogen mitigation technologies.