Experimental characterization of an oxygen transfer model of a fine pore diffuser aerator.

Dissolved oxygen (DO) is an important aspect of water quality in aquaculture. To prevent oxygen deficiency, aeration is used to improve DO and increase yields in aquaculture farms. However, the experimental quantification of standard oxygen transfer rate (SOTR) of aerators is highly case dependent and varies under different aerator operational conditions. Hence, using SOTR for modeling, simulation, and aerator design purposes tends to be unreliable. This work validates an existing theoretical oxygen transfer model of an economical fine-pore diffuser using a bench-scale aeration system. Modifications were made to the model to account for physical conditions and to relate the model to SOTR. Aeration tests were conducted using various airflow rates and diffuser depths for three water volumes (137 L, 160 L, 192 L). As a parameter to the model, bubble diameters were determined for each experiment using an automated image processing tool developed for this study. The percentage error between the theoretical and experimental oxygen transfer coefficients range from 12.87% to 19.99% and are well within the 95% confidence interval of both respective results. The oxygen transfer coefficient and rate increased with diffuser submergence and airflow rate. However, standard aeration efficiency decreased exponentially with increasing airflow rates. The use of this model provides an approximate estimate of oxygen transfer rates in different conditions, which can be used to optimally design aerators and strategically create cost-saving practices for both intensive and extensive aquaculture applications. [ABSTRACT FROM AUTHOR]