Increasing economic and environmental benefits of media-based aquaponics through optimizing aeration pattern

Aquaponics is the cultivation form that integrates aquaculture with hydroponics to nurture plants and fish simultaneously. And aeration plays an important role in its sustainable operation, as well as economic and environmental feasibility. In this study, two patterns to reduce aeration intensity, i.e., semi-aeration (SA) and intermittent aeration (IA) were used to improve the economic and environmental benefits of media-based aquaponics. Results showed that SA aquaponics, in which the energy efficiencies on culturing fish and crop were improved respectively by 78.20% and 77.61% compared with Control, had the potential to obtain higher economic benefits. Although both SA and IA could save half of the aeration cost by reducing aeration flux and time respectively, the product yields in SA weren't impaired seriously while in IA aquaponics they were. And the nitrogen utilization efficiency (NUE) of SA aquaponics was 11.3% higher than that of IA aquaponics, mainly attributed to the more stable dissolved oxygen concentration in SA. Better water quality was obtained in IA aquaponics, however, it was achieved at the cost of higher N loss (mainly in the form of N2), which subsequently reduced the potential for further improvement of NUE. Both SA and IA could considerably reduce GHG emissions from aquaponics, due to lower energy requirement. IA aquaponics showed the lowest N2O emission, but the primary source (over 97%) of greenhouse gases (GHG) emissions from aquaponics was off-site indirect CO2 emission. Taking productivity and environmental impact into consideration, semi-aeration was believed to be a better choice when reducing aeration.