RESUMO
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.
RESUMO
Performance of recirculating aquaculture systems in the intensive farming of Pacú Piaractus mesopotamicus (Characiformes: Characidae). An alternative to intensify fish production, reducing the environmentalimpact and production costs are recirculating aquaculture systems (RAS). The performance of a RASwas evaluated, as fish growth and water quality conditions, in a culture of Piaractus mesopotamicus reared forornamental purposes. Two commercial food brands with different protein contents (18%-TI and 28%-T2), weregiven to juvenile fishes during an eight weeks period. Growth was measured bi-weekly: standard length (Lp),peak height (A), weight and multiple condition factor (KM). The evaluation of water parameters included: dissolvedoxygen, NH3-NH4, pH, NO2, NO3, KH carbonate hardness and PO4. NH3-N rate production was analyzedfollowing Timmons-Ebeling model. Results demonstrated significant differences in weight only, and T2 showeda 7.5% higher value than T1; nevertheless, treatment T1 had a higher KM. In general, water quality valueswere suitable for growth: OD=T1: 4.23±1.23; T2: 4.13±0.86; NH3=T1: 0.02±0.02; T2: 0.06±0.10; however,pH was an exception (T1: 6.95±0.98; T2: 7.11±1.03), displaying lethal rates (<5) by the fifth week. SystemsNH3 removal had a 99.4% to 100% efficiency. Final fish biomass was 22.03kg for T1 and 27.49kg for T2. Weconcluded that the systems were able to maintain suggested density up to the experimental fifth week. Waterquality parameters remained in suitable levels, with the pH exception. Cultured fishes reached their commercialsize (10cm) in eight weeks.
Una alternativa que permite intensificar la producciónacuícola, y reducir el impacto ambiental y los gastosde operación son los sistemas acuícolas de recirculación(SAR). Se evaluó el desempeño de SAR AquaticEcosystems® en el cultivo ornamental de Piaractus mesopotamicus,y se estimó el crecimiento y la calidad del agua,con dos alimentos comerciales de 18 (T1) y 28% (T2) deproteínas. Del crecimiento se midieron quincenalmente:la longitud patrón, altura máxima, peso y factor de condiciónmúltiple (KM). De la calidad de agua se evaluósemanalmente, O.D., NH3-NH4, pH, NO2, NO3, KH y PO4.Con el modelo de Timmons-Ebeling se calculó la tasa deproducción de NH3-N. Los resultados muestran diferenciassignificativas en el peso, donde T2 presentó un incrementode 7.14% más que T1, que mostró un mayor KM. La calidad del agua fue adecuada en los parámetros limitantes(OD=T1: 4.23±1.23; T2: 4.13±0.86; NH3=T1: 0.02±0.02;T2: 0.06±0.10), a excepción del pH (T1: 6.95±0.98; T2:7.11±1.03) que presentó valores letales (<5) a partir de laquinta semana. La remoción de NH3 fue de 99.4 a 100%. La biomasa final fue de T1: 22.03kg y T2: 27.49kg. Se concluye que los sistemas pudieron alojar la densidad propuestasolo hasta la quinta semana de experimentación. Los peces tardaron cuatro quincenas en llegar a talla comercial de ornato.