Membrane aerated biofilm reactor in recirculating aquaculture system for effluent treatment.

The implementation of fish farming has been increasing worldwide over the last decades, as well the search for alternative production systems and the treatment of their generated effluent. Recirculating Aquaculture System (RAS) is a compact solution for future intensive fish farming. However, few configurations of treatment technologies were tested in RAS, such as systems with a Membrane Aerated Biofilm Reactor (MABR). In this scene, this study aimed to evaluate the RAS effluent treatment efficiency device for intensive Nile tilapia (Oreochromis niloticus) production, the fish species most cultivated worldwide. The novel RAS configuration was composed of a cultivation tank (CT), a Column Settler, and a MABR. The RAS performance was evaluated by pH, temperature, turbidity, dissolved oxygen (DO), total nitrogen (TN), ammonia, nitrite, nitrate, total solids (TS), and chemical oxygen demand (COD). The obtained results in average values for temperature, pH, and DO inside the CT were 25.22 ± 1.88°C, 7.61 ± 0.33, and 3.80 ± 1.30 mg L-1, respectively, as ideal for tilapias survival. Average removal efficiencies found in the RAS for turbidity, COD, TN, nitrite, nitrate, ammonia, and TS were 50.0, 40.5, 11.7, 40.2, 13.1, 35.0, and 11.4%, respectively. Overall, we observed removals for all parameters studied, with good results, particularly, for COD, turbidity, nitrite, and ammonia. The evaluated system proved an effective alternative for water reuse in RAS capable of maintaining water quality characteristics within the recommended values for fish farming.

Eficiência na remoção de NAT, DBO e DQO utilizando reator aeróbio de leito fluidizado com circulação em tubos concêntricos associado ao decantador de coluna em uma produção intensiva de tilápia / Removal efficiency of TAN, BOD and COD by using aerobic fluidized bed reactor with circulation in concentric tubes associated to a column settler in intensive production of tilapia

RESUMO O desenvolvimento da aquicultura intensiva é acompanhado de um crescente impacto ambiental produzido pelos efluentes gerados. Os sistemas de recirculação para aquicultura (SRA) são uma alternativa compacta e trabalham com elevadas densidades de estocagem e menores volumes de água. Foi utilizado um decantador de coluna (DC) associado ao reator aeróbio de leito fluidizado com circulação em tubos concêntricos (BAS-CT) com tempo de retenção hidráulica (TRH) de 0,55 e 0,20 h respectivamente, num SRA com tilápias de 0,32 kg de peso médio e densidade de estocagem de 33,1 kg.m-3 em relação à remoção do nitrogênio amoniacal total (NAT), demanda bioquímica de oxigênio (DBO) e demanda química de oxigênio (DQO). As eficiências na remoção de NAT, DBO e DQO foram 35,2, 48,0 e 64,9%, respectivamente. No uso de DC com o BAS-CT, obteve-se bom desempenho, com baixos TRH no tratamento do efluente.

ABSTRACT The development of intensive aquaculture is accompanied by an increasing environmental impact produced by the wastewater generated. The recirculating aquaculture systems (RAS) are a compact alternative and manage high stocking densities and lower volumes of water. It was used a column settler (CS) associated with aerobic fluidized bed reactor (BAS-CT) with hydraulic retention time (HRT) of 0.55 and 0.20 h respectively, in RAS with tilapias with average weight of 0.32 kg and storage density of 33.1 kg.m-3 regarding the removal of total ammonia nitrogen (TAN), biochemical oxygen demand (BOD) and chemical oxygen demand (COD). The removal efficiencies of TAN, BOD and COD were 35.2, 48.0 and 64.9%, respectively. The use of CS with the BAS-CT showed a good performance with low HRT in the treatment of this effluent.