Waldir Medri

Modelling and Optimisation of Stabilisation Ponds System for the Treatment of Swine Wastes: organic Matter Evaluation

The fast increase of the swine production, specially in the west region of Santa Catarina, Brazil, did not have a parallel program for the valorisation of its dejection, not even processes for the treatment of the organic residues. Most of the producers keep their animals confined in small areas, having as a consequence the production of a large volume of wastes in the same place. This waste is diluted in water used to clean the bays, resulting in contamination of the watercourse. Thus, it is necessary to develop treatment processes to minimise the environmental problems caused by the swine breeding activities. The stabilisation ponds have been used due to its excellent efficiency in the removal of the organic matters, solids, nutrients and faecal coliforms; besides the low implantation and maintenance costs. This work was assisted in a series of four stabilisation ponds, real scale, treating swine wastes in Concordia/SC at CNPSA. The ponds system was evaluated during a period of 20 months, objecting to get its principal work parameters, as well as information about the capital and operational costs, in order to adjust the equations to model and optimise the systems about the removal of the organic matters.

Growth of Nile tilapia Oreochromis niloticus fed diets with different levels of proteins of yeast

This experiment was based on observations of 72 juveniles of Nile tilapia (Oreochromis niloticus), sexually reverted with an initial mean weight of 37.27 ± 4.92g, distributed in 12 cages of 100 l to evaluate the effects of the yeast inclusion as proteins source in the diet. The fishes were distributed in a completely randomized design with four treatments (0; 20; 40; and 60%) of yeast protein in substitution to the protein of traditional sources with three repetitions. Effects of the treatments were not observed (p > 0.05) on the survival and to food conversion. It was observed a quadratic effect on weight gain (Y = 73.39 + 0.173X - 0.0034X2; R2= 0.9986). It was concluded the best level of yeast inclusion as source proteins in the diet for reversed Nile tilapia juvenile was 25.44%.

A Mathematical Model for the Removal of Organic Mater in Stabilization Ponds

This work presents an application to systemize the construction of ponds systems for treatment of domestic sewage. It consisted of two anaerobic ponds operated in parallel during May/97 to April/99. These were connected in series with a chicaned facultative pond. The treatment system was controlled with samples collected from the crude sewage (compound sample), in the affluents and effluents of the ponds and along the flux of the anaerobic and facultative ponds. The following parameters were analyzed: pH, Biochemical Oxygen Demand, Chemical Oxygen Demand, Total Solids, Sedimentable Solids, Total Coliforms, Oxygen Consumed in Acid Medium (OCAM) and temperature.

A model for cost estimation of system for piggery wastes treatment ponds: a case study

This article presents the results from the monitoring of a system of ponds for the treatment of piggery wastes, carried out during a 20 months period, with the objective to determine design parameters for the optimization of the treatment system. A series composed of two anaerobic ponds, one facultative pond and one water hyacinth pond, gave an efficiency of 97% in the removal of BOD5, 93% for total phosphorus, 91% for total Kjeldahl nitrogen and a removal of 7 log units for fecal coliforms. A model of the optimization incurred in the treatment of these wastes was developed, within economic concepts.