Integration of down-flow hanging sponge reactor to oreochromis niloticus − Brassica oleracea aquaponics system

• Published in: Journal of environmental science and health. Part A, Toxic/hazardous substances & environmental engineering Vol. 59; no. 7; pp. 358 - 368
• Main Authors: Kotcharoen, Wilasinee, Nagai, Zen, Watari, Takahiro, Adlin, Nur, Hatamoto, Masashi, Murakami, Yuki, Maharjan, Namita, Takeuchi, Yutaka, Yamazaki, Shinichi, Yamaguchi, Takashi
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 06-06-2024; Taylor & Francis Ltd
• Subjects: Aeration tanks; Aquaculture; Aquaponics; Bacteria; Brassica; Brassica oleracea; Conversion ratio; Dissolved oxygen; Feed conversion; Feeding rates; Fish; Food industry; Food production; Food security; Gene sequencing; Hydroponics; Nitrification; Nitrifying bacteria; nitrogen removal; Oxygen; Oxygen transfer; Performance evaluation; Reactors; rRNA 16S; sponge-based trickling filter; Survival; Tilapia; Water purification; Water quality; Aquaponics; oxygen transfer; sponge-based trickling filter; nitrogen removal
• ISSN: 1093-4529; 1532-4117; 1532-4117
• DOI: 10.1080/10934529.2024.2399444

Aquaponics is a promising solution for addressing food security concerns. Nonetheless, an effective water-purification system is necessary to achieve high and stable yields of fish and vegetables. This study aimed to evaluate the nitrification and oxygen transfer performance of a laboratory-scale down-flow hanging sponge (DHS) reactor with a Brassica oleracea aquaponics system to treat water in an Oreochromis niloticus closed-aquaculture system. The DHS reactor showed a higher oxygen transfer coefficient (K
L
a) than the conventional aerator and provided an adequate dissolved oxygen (DO) concentration of approximately 5.5 mg/L essential for O. niloticus growth throughout the experimental period. The evaluated DHS-based aquaponic system maintained high water quality in an aquaculture tank, with a survival rate of 97%. The O. niloticusgrew at a low feed conversion ratio of 1.5-2.1 and a low feeding rate of 0.5% at high stocking densities of 17.5-22.2 kg-fish-weight/m
3
. 16S rRNA gene sequencing indicated that the DHS sponge carrier effectively retained nitrifying bacteria such as Nitrosomonas and Nitrospira. This study demonstrated that the DHS reactor provided a high DO concentration and that a simultaneous DHS reactor with a hydroponic tank provided a low-cost aquaponic system that could be applied for food production in the aquaculture industry.