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The objective of this work was to evaluate the use of crude glycerol as an energy source to replace corn, in diets for Nile tilapia (Oreochromis niloticus) in the fattening stage. Two hundred Nile tilapia (190±4.5 g) were distributed in 20 tanks, in a completely randomized design. The treatments consisted of crude glycerol at 0, 60, 120, 180, and 240 g kg-1, to replace the dietary levels of corn, in order to maintain a constant digestible energy. Fish productive performance and the chemical composition of the fillet were evaluated. Histological analyses of the hepatopancreas, intestine, and visceral fat were also carried out. Crude glycerol had no effect on the performance parameters; however, it caused a quadratic reduction of visceral fat. There was an increase in the moisture and a decrease in the ether extract of the fillet. A linear effect on the blood glucose levels was verified in fish fed the diet without glycerol, and the peak occurred at 90 min. There were no differences for measurements of intestinal villi height and hepatocyte area. Crude glycerol can replace corn in diets for Nile tilapia in the fattening stage, without adversely affecting fish metabolism, productive performance, or survival.

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The aim of this study was to evaluate the production performance of Nile tilapia post-larvae and fingerlings fed with increasing levels of alcoholic extract of propolis into diets. In Experiment 1, 1800 post-larvae were distributed in 30 tanks, in a completely randomized design with five treatments composed by the inclusion of 0, 1, 2, 3 and 4 g of dry propolis/kg of feed, and six replicates. In experiment 2, 1600 fingerlings were distributed in the same system and designed as experiment 1. No significant effect was observed between treatments, for final weight, total and standard length, survival, and intestinal villus height. However, the propolis extract inclusion of 1 g/kg in Nile tilapia post-larvae and fingerlings' feed resulted in a better body condition factor and higher body protein deposition (p<0.05). The condition factor is an estimate for the future growth of the animals, possibly the fish treated with propolis extract will present better growth, survival and greater reproductive potential rates. The results of the present study demonstrate that alcoholic extract of propolis improves the nutritional condition of Nile tilapia post-larvae and fingerlings, potentially leading to increased productivity in subsequent stages, as well as leading to improvement in fingerlings muscle deposition.

Intensive aquaculture needs to adopt techniques that are able to contribute towards sustainability. Closed systems that employ water recirculation can combine intensive production with environmental sustainability, since there is no exchange of water or discharge of effluents into the environment. In order to achieve this, effective filtration systems are required to ensure that the water quality is satisfactory for the cultivation of aquatic organisms. Chitosan, an industrial waste material derived from crustacean farming, is a renewable natural material that is biodegradable and possesses adsorbent characteristics. In this work, chitosan foam was incorporated in filters and was evaluated as an adsorbent of aquaculture pollutants, adding value to the material and at the same time providing a use for industrial waste. The foam was characterized by scanning electron microscopy and energy dispersive spectroscopy, apparent density, and water absorption capacity. It was used to remove ammonia, nitrite, orthophosphate, and turbidity from aquaculture effluents. The foam consisted of a bilayer with smooth and porous sides, which presented low density, flexibility, and high water absorption capacity. The best proportion of the foam, in terms of the mass of foam per volume of solution (% m v), was 0.10, which resulted in removal of 32.8, 57.2, 89.5, and 99.9% of ammonia, nitrite, orthophosphate, and turbidity, respectively. This biopolymer produced is biodegradable, and when saturated with organic compounds from aquaculture, and no longer suitable for reuse as a filter material, it can be employed as a fertilizer, hence closing the sustainability cycle of the aquaculture production chain.

O efluente proveniente de abatedouro avícola tem grande capacidade produtora de biogás, devido a sua constituição rica em matéria orgânica. Os principais gases produzidos durante a degradação dos constituintes orgânicos são o metano, dióxido de carbono e o óxido nitroso. Um método amplamente empregado no tratamento de resíduos é a biodigestão anaeróbia para captação destes gases. Em indústrias do ramo avícola os efluentes gerados possuem a característica de elevadas cargas de óleos e graxas, sólidos suspensos, nitrogênio, fósforo, proteína e lipídios, que são os responsáveis pela alteração do pH, dos sólidos totais, da demanda bioquímica de oxigênio, da demanda química de oxigênio (DQO), entre outros parâmetros. A caracterização físico-química das águas, efluentes industriais e também dos resíduos industriais, consiste em serviços de determinação no campo e a utilização do controle analítico de laboratório relativo aos parâmetros físico-químicos. Objetivou-se a caracterização físico-química do efluente pré-tratado para se estimar o potencial de geração de biogás, a partir da instalação de um biodigestor anaeróbico na lagoa que o recebe, de um abatedouro de aves da região Oeste do Paraná. Para caracterização do efluente pré-tratado e avaliação da possibilidade de instalação de um biodigestor, foram analisados os parâmetros físico-químicos: demanda química de oxigênio, sólidos totais, sólidos voláteis, sólidos dissolvidos, sólidos fixos, sólidos suspensos, potencial hidrogeniônico, óleos e graxas, e nitrogênio amoniacal, seguindo as metodologias propostas pela APHA (1995). Os procedimentos foram realizados no Laboratório de química orgânica da Universidade Federal do Paraná – setor Palotina. As estimativas médias previstas pelo Centro para a Conservação de Energia, citadas por Brondani (2010) para o dimensionamento de propostas destinadas ao comércio de carbono mencionam uma produção de 0,35 m3 de metano para cada 1 kg de DQO de efluente avícola adicionada ao biodigestor. Se a DQO de entrada na lagoa é 2285 mg L-1, vazão média de 260 m3 h-1, é possível gerar 4990,44 m3 de metano/dia. Como parâmetro para cálculo do potencial de produção, adotou-se o valor de 70% de metano na composição do biogás, logo teremos o equivalente a 7129 m³ de biogás/dia. A biodigestão anaeróbia é um dos melhores processos para o tratamento de efluentes oriundos de abatedouros, como pontos positivos do processo, pode-se citar a produção de energia, redução da matéria orgânica, diminuição de odores desagradáveis e a eliminação de patógenos.

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