Avaliação da toxicidade de efluentes da parboilização de arroz e do abate de suínos

Abstract

This thesis aimed evaluate the toxicity of rice parboiling process and swine slaughterhouse with sausage manufacturing effluents through bioassays with three organism test of the different trophic levels: fish, seeds and bacteria. For the physicochemical characterization of the effluents were evaluated: Biochemical Oxygen Demand - BOD, Chemical Oxygen Demand - COD, Total Suspended Solids, Total Kjeldahl Nitrogen - TKN, Ammoniacal Nitrogen, Total Phosphorus, Chloride, Surfactants, Sulfides, Hardness, Aluminum, Manganese, Iron, Zinc, Phenols, Electrical Conductivity, Salinity, pH and Temperature. For the toxicity fish evaluation was used the zebrafish (Danio rerio) sperm quality, analyzing the sperm motility rate and motility period, integrity and viability of sperm membrane, mitochondria functionality and DNA integrity. The phitotoxicity evaluation was measured through germination seed tests of lettuce (Lactuca sativa) and cucumber (Cucumis sativus), taking into account germinated seeds number, root length and germination index. The bacteria toxicity was availed using a portable respirometer with Escherichia coli as bioindicator. The results of physicochemical characterization and bioassays were statistically correlated, to identify the causes of toxicity. The most physicochemical parameters were according with the Brazilian legislation limits to effluents discharge, excepting TKN and phosphorus concentration in swine slaughterhouse effluent. Both wastewater treatment plants evaluated also contributed to the reduction of toxicity. Nevertheless, both effluents presented toxicity to zebrafish sperm quality, indicating that your release in the surface water could affect the fish fertilization. It was observed phytotoxicity to cucumber seeds in all the evaluated effluents, but for lettuce seeds, only was registered phytotoxicity for the swine slaughterhouse and treated effluent parboiled rice, indicating agricultural use of these effluents could compromise the cultivation of plants. Wasn´t registered toxicity for all effluent evaluated using the bioindicator Escherichia coli. Considering the strong negative correlation found, were considered as potential causes of toxicity of the parboiled rice effluent: (i) sperm quality: phosphorus, suspended solids, salinity, iron and BOD; (ii) phytotoxicity: iron and manganese. Relative to the swine slaughterhouse effluents, were considered as potential causes of toxicity: (iii) sperm quality: Chloride, BOD, COD, Iron, Manganese, N-NH3, TKN, Surfactants, Electrical Conductivity Salinity; (iv) phytotoxicity: TKN, Surfactants and Zinc. With the identification of these contaminants, the agro-industries can improve your treatment plants and thus reduce the toxicity of effluents for the attendance to environmental regulations.