Alcoholic extract of propolis in Nile tilapia post-larvae and fingerlings' diets: effects on production performance, body composition and intestinal histology.

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.

Physico-chemical, microbiological and ecotoxicological evaluation of a septic tank/Fenton reaction combination for the treatment of hospital wastewaters.

Hospital wastewater is considered a complex mixture populated with pathogenic microorganisms. The genetic constitution of these microorganisms can be changed through the direct and indirect effects of hospital wastewater constituents, leading to the appearance of antibiotic multi-resistant bacteria. To avoid environmental contamination hospital wastewaters must be treated. The objective of this study was to evaluate the efficiency of hospital wastewater treated by a combined process of biological degradation (septic tank) and the Fenton reaction. Thus, after septic tank biodegradation, batch Fenton reaction experiments were performed in a laboratory-scale reactor and the effectiveness of this sequential treatment was evaluated by a physico-chemical/microbiological time-course analysis of COD, BOD(5), and thermotolerant and total coliforms. The results showed that after 120min of Fenton treatment BOD(5) and COD values decreased by 90.6% and 91.0%, respectively. The BOD(5)/COD ratio changed from 0.46 to 0.48 after 120min of treatment. Bacterial removal efficiency reached 100%, while biotests carried out with Scenedesmus subspicatus and Daphnia magna showed a significant decrease in the ecotoxicity of hospital wastewater after the sequential treatment. The use of this combined system would ensure that neither multi-resistant bacteria nor ecotoxic substances are released to the environment through hospital wastewater discharge.