Among the animal protein production activities, world aquaculture has the highest growth rate, and is mainly practiced in ground-excavated ponds. However, with great productivity comes the concern about the increasing generation of effluents, mainly at the moment of fish removal, when high loads of organic matter and nutrients are released into the environment. Thus, this study evaluated the quality of effluents through the principal component analysis (PCA) in samples from nurseries of different sizes in four sampling scenarios. Analysis was performed during the process of fish removal in Nile Tilapia intensive fish farming sites at various properties in the Western region of Paraná State in Brazil. Twenty physical and chemical parameters were analyzed in each effluent sample using standard methods of effluent analysis. The results indicated that the concentrations of Suspended Solids (SS), Total Solids (TS), Chemical Oxygen Demand (COD), and Total Phosphorus (TP) increased significantly at the end of the fish removal process, which caused a progressive deterioration in the effluent released into the environment. Hence, regulating water management during cultivation, as well as mitigating the effects of effluent generated in fish removal, is indispensable to maintain the legality, profitability, and sustainability of this sector.

RESUMOO uso de macrófitas aquáticas pode ser uma alternativa para o tratamento e minimização dos efluentes gerados na piscicultura. Objetivou-se com este trabalho verificar a eficiência do aguapé (Eichhornia crassipes) na melhora de variáveis limnológicas (fósforo e amônia) com cultivo de tambaqui (Colossoma macropomum) em canais com fluxo contínuo de água. O experimento foi conduzido por um período de 60 dias com amostragens quinzenais em canais de abastecimento, seccionados com telas e utilizando uma densidade de 120 peixes m-³. As seções foram divididas em etapas, alternando com presença e/ou ausência de aguapé. Não foram constatadas diferenças significativas nos teores de amônia, alcalinidade e dureza do efluente, nos tratamentos com ou sem a presença dos aguapés, contudo foi comprovada a eficiência do aguapé na remoção de nutrientes como o fósforo nas primeiras semanas de cultivo, sendo recomendado, o seu uso em sistemas de criação de peixes. PALAVRAS-CHAVE: Eichhornia crassipes, fósforo, amônia, qualidade de água Biofilter efficiency of water hyacinth on limnological variables in irrigation channels used for tambaqui farming ABSTRACTThe use of biofilter of aquatics plants can be an alternative for the treatment and minimization of effluents generated in fish farming. The objective of this work was to evaluate the effect of water hyacinth (Eichhornia crassipes) in the improvement of the limnological variables of water of supply channels used for fish farming. The experiment was conducted in supply channels over a period of 60-days at sampling intervals of fifteen days. The channels were sectioned with screens. A density of 120 fish m -³was used. The sections were divided into stages, alternating with presence or absence of water hyacinth. It was not observed significant differences in the level of ammonia (p >0.05), alkalinity and hardness of the effluent in both treatment systems. However it was observed that water hyacinth was efficient in the removal of nutrients such as, phosphorus (first weeks of cultivation). The use of water hyacinth can be recommended in fish farming systems.

ResumoO presente trabalho teve por o objetivo avaliar a produção de biomassa das macrófitas aquáticas aguapé (Eichhornia crassipes) e egeria (Egeria densa) em um sistema de tratamento de efluente de piscicultura orgânica, sob 3 condições de tempo de detenção hidráulica. O sistema foi composto por 18 tanques experimentais de 2,00 x 1,00 x 0,65 m de comprimento, largura e profundidade, respectivamente, revestidos com lona de polipropileno. O delineamento foi inteiramente casualizado, com 2 macrófitas, 3 tempos de detenção hidráulica ( , seguido pelos TDH de 8 e 4 horas, não diferindo entre os TDH (P>0,05). Concluiu-se que o aguapé produziu mais biomassa que a egeria em todos os TDH avaliados. Palavras-chave: Aproveitamento de resíduo, redução de poluição, tempos de detenção hidráulica AbstractThe objective of this research was to evaluate the production of biomass of the aquatic macrophytes water hyacinth (Eichhornia crassipes) and egeria (Egeria densa) in three hydraulic detention times in a organic pisciculture effluent treatment system. The system was composed for 18 experimental tanks of 2.00 x 1.00 x 0.65m length, width and depth respectively, coated with polypropylene canvas. An entirely randomized 2 macrophytes x 3 hydraulic detention times (HDT) and 3 repetitions. The HDT used was 4, 8, and 12 hours. The biomass production was evaluated at the end of the experiment which was extended at 08/07 to 19/08/2006. The water hyacinth showed the best results of biomass production (P<0.05),

The purpose of this study was to determine the total nitrogen (TN) and total phosphorus (TP) balance during intensive tilapia farming in excavated ponds. To quantify TN and TP released into the environment, the supply water, effluents at the harvest time, fish composition, feed, and sediment were analysed. The mass balance between the amount of nutrients that is inserted through the feed, which is transformed into biomass by the fish and is retained in the sediment was calculated based on dry matter. The nutrient load arriving from the supply water was calculated as a function of the concentration of TN and TP. The TN and TP dynamics during the harvesting process in three different pond sizes identified that, on average, 2.37% of TN and 2.05% of TP inserted into the system during rearing is eliminated with 10.64% TN and 37.01% TP are retained in the sediment. The TN and TP input into the system occurs through the water supply, young fish, and the feed, the latter being responsible for about 92.87% TN and 96.05% TP. The feed composition indicates that the P level of the food is above the nutritional recommendations for the species. The amount of TP accumulated in the sediments indicates that there is a need for good management practices for water quality during the rearing and sediment management period before the beginning of a new production cycle.

RESUMOA ocorrência de compostos nitrogenados em água residuária de abatedouro de tilápia acima dos limites legais, tem causado sérios problemas de poluição em corpos d'água receptores. O processo biológico para remoção dessas substâncias comumente encontradas sob a forma de nitrogênio amoniacal, é conhecido como nitrificação. Objetivou-se, com o presente trabalho, estudar o efeito do tempo de reação (TR) e da aeração na eficiência da remoção de nitrogênio amoniacal e na conversão do nitrogênio amoniacal a nitrato, de água residuária de abate de tilápia em um reator em batelada sequencial com biofilme. O experimento foi executado usando-se dois TR(6 e 12 h) e dois níveis de vazão de ar (3 e 6 L min -1 ); avaliaram-se quatro tratamentos a partir da combinação dessas variáveis configuradas em um planejamento experimental do tipo factorial 2 2 , sendo: T1 (QAr = 3 L min -1 e TR = 6 h); T2 (QAr = 6 L min -1 e TR = 6 h), T3 (QAr = 3 L min -1 e TR = 12 h) e T4 (QAr = 6 L min -1 e TR = 12 h), e quatro repetições para cada tratamento. Os resultados mais significativos foram para o tratamento T4, com o qual se obteve média de eficiência para conversão de amônio a nitrato e remoção de nitrogênio amoniacal de 57,27 ± 27,05% e 81,90 ± 3,80%, respectivamente. Palavras-chave: aeração, tempo de reação, RBS, remoção de nitrogênioNitrification of tilapia slugtherhouse effluent according to the aeration conditions and reaction time ABSTRACTThe occurrence of composts of nitrogen above the legal limits has been causing serious pollution problems in water receptor bodies. The biological process for removal of these substances commonly found in the ammoniacal nitrogen form is known as nitrification. The present study had as its objective the evaluation of the effects of the reaction time (TR) and of the aeration on the removal efficiency of the ammoniacal nitrogen and on the conversion of the ammoniacal nitrogen to nitrate in a nitrification process of the tilapia slaughterhouse effluent in sequential batch reactor with biofilm. The experiment was performed using two reaction times (6 and 12 h) and two levels of air flow (3 and 6 L min -1 ), four treatments, starting from the combination of these two variables, were evaluated in an experimental planning of the factorial 2 2 type: being: T4 (QAr = 3 L min -1 and TR = 6); T2 (QAr = 6 L min -1 and TR = 6), T3 (QAr = 3 L min -1 and TR = 12) and T1 (QAr = 6 L min -1 and TR = 12), and four repetitions. The most significant results were obtained for treatment T4, where the efficiency for conversion of the ammoniacal nitrogen to nitrate obtained was 57.27 ± 27.05 and removal of the ammoniacal nitrogen was 81.90% ± 3.80.

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RESUMO. Foram utilizados 125 indivíduos com peso inicial de 3,25 ± 0,94 g e comprimento inicial de 6,29 ± 0,63 cm, distribuídos em um delineamento inteiramente casualizado em 25 aquários de 35 L. Os tratamentos consistiram na moagem dos ingredientes da ração em moinho com peneiras de 0,50; 0,75; 1,00; 1,25 e 1,50 mm, com respectivo diâmetro geométrico médio (DGM) de 245,50; 317,23; 345,29; 366,04 e 450,28 µm. Não foram observadas diferenças no comprimento final médio, no peso final médio, na conversão alimentar aparente, no ganho de peso diário e na taxa de eficiência protéica, entre os diferentes graus de moagem. A velocidade de trânsito do alimento foi maior para rações com partículas maiores (345,29; 366,04 e 450,28 µm). Alevinos de piavuçu podem ser alimentados com rações utilizando DGM dos ingredientes, variando de 245,50 até 450,28 µm, sem prejuízo ao seu desempenho.Palavras-chave: moagem, desempenho, Leporinus macrocephalus, piavuçu, velocidade de trânsito.