Efeitos fitotóxicos do lodo gerado no processo de clarificação da água de abastecimento.

Abstract

The production of drinking water has as a by-product the generation of sludge from washing filters and decanters, due to the use of chemical products to adapt to potability standards. Sludge can contain a portion of toxic substances and cause environmental degradation. Therefore, the present work aimed to analyze the toxic effects of sludge produced in the water clarification process, using vegetable seeds as bioindicators. To this end, the methodology used consisted of a composite collection of water carried out in April of this year in a stretch of the Piancó River, located approximately 400 meters from the Pombal-PB ETA intake point. After collection, it was necessary to add 100 g of clay extracted from a Kaolin mine and 100 g of soil, to provide sufficient turbidity to generate a considerable amount of sludge. Next, the physical-chemical characterization of the raw water and the jar test were carried out using dosages of 10, 15 and 20 mg.L-1 of aluminum sulfate, where the coagulant dosage was determined. ideal, followed by the characterization of the clarified water and sludge. For phytotoxicity tests, seeds of Lactuca sativa (lettuce), Brassica oleracea var. Capitata (cabbage) and Cucumis sativus (cucumber). The results showed that the natural sludge presented a severe degree of toxicity at different concentrations of aluminum sulfate, with inhibition of root development and a Germination Index (GI) of less than 40%. Therefore, this effluent should not be released into the soil and water bodies without undergoing adequate treatment, aiming to minimize negative environmental impacts on different environmental factors.