A hybrid degasser for improved CO removal and oxygenation in recirculating aquaculture systems: Toward sustainable water quality control

Effective gas management remains a major challenge in water treatment, particularly in recirculating aquaculture systems (RAS), where excessive carbon dioxide ( CO 2 ) accumulation and oxygen depletion can deteriorate water quality and reduce production efficiency. To address these challenges, this study presents the development and performance evaluation of a hybrid degasser designed to enhance CO 2 removal and oxygenation in RAS operations. The performance of the hybrid degasser was evaluated using polypropylene packing media (PPM), ceramic packing media (CPM), and a combination of both. Initial experiments were conducted using these three configurations (PPM, CPM, and PPM + CPM), with packing media heights ranging from 10 to 90 cm and gas-to-liquid ratios ranging from 4 to 16. The results revealed that the combined PPM + CPM configuration significantly outperformed the individual media types in terms of the volumetric CO 2 mass transfer coefficient ( k L a T ) and the standard CO 2 transfer rate ( SCTR ). Subsequent experiments were conducted using the fixed combined media configuration while varying geometric and dynamic parameters based on dimensional analysis. An optimal geometric similarity among linear dimensions was identified, and the Reynolds number ( Re ) was found to have a significant influence on degasser performance. Predictive simulation equations were developed based on the Reynolds criterion within the 8576 ≤ Re ≤ 45,914 range. Overall, these findings provide valuable insights into the application of hybrid degassers for effective CO 2 removal and enhanced oxygenation in RAS, contributing to the maintenance of optimal water quality. • A hybrid degasser was developed using different packing media configurations. • Mathematical models were developed to assess degasser performance. • The developed models were validated against data from previous studies. • CO 2 removal and oxygenation were assessed to support water quality in RAS.