EFFECT OF AN SINGLE SLUDGE DENITRIFICATION REACTOR ON GROWTH PERFORMANCE AND ENVIRONMENTAL SUSTAINABILITY OF STRIPED CATFISH Pangasianodon hypophthalmus, Sauvage, 1878 FARMING

N. Nhutab*, N.H.Quana, N.V. Haoa, R.H. Bosmab, M.C.J. Verdegemb,  J.A.V. Verrethb and  E.H. Edingb
a Research Institute for Aquaculture No 2, 116 Nguyen Dinh Chieu, District 1, Hochiminh City, Vietnam. nhut300676@yahoo.com
b Aquaculture and Fisheries Group, Department of Animal science, Wageningen University, Wageningen, The Netherlands.

The striped catfish culture is the biggest aquaculture industry in Vietnam. Every year, about 1.1 million MT production comes from ponds, and exports over 130 countries. For more sustainability, closed culture system for striped catfish is necessary to improve sustainability indicators for striped catfish industry in Mekong delta, Vietnam.

This  study aims to assess improving sustainability indicators for striped catfish culture through recirculating aquaculture system (RAS) integrated with a denitrification reactor (USB). A mono factorial experiment was designed with two levels: level 1 being a conventional RAS in which no USB was installed (RAS), level 2 being a conventional RAS extended with a USB-denitrification  reactor (RAS+USB) (Figure 1).

The results showed that fish density, fish growth, fish quality and realized feed conversion ratio in RAS + USB were comparable with RAS (P > 0.05). Water and NaHCO3 use in RAS + USB were much lower than RAS (P < 0.05).

Fish biomass retained dry matter (34-37 % of feed input), nitrogen (48.9-49.2 % of feed input), and  phosphorous (20-23 % of feed input) were similar between RAS and RAS + USB (P > 0.05). However, dry matter, N and P discharge per 1 kg feed input in RAS + USB were much lower than RAS (P < 0.05).

The USB reactor removed 11.2 g for NO3-N, 12.3 g for N, 1.5 g for P, 34.4 g for COD and 145 g for dry matter per 1 kg feed input, respectively. About 53g alkalinity as CaCO3 per 1 kg feed input was produced.

RAS + USB system indicated to improve sustainability indicators for striped catfish culture, and it is recommended to upscale commercial size.