Extrato de acácia negra no tratamento primário de água fluvial
Palavras-chave:Coagulation, Flocculation, Turbidity, Water quality, Basic sanitation
In water and effluent treatment processes are used inorganic coagulants not biodegradable from aluminum salts and iron (aluminum sulfate, ferric chloride, ferric sulfate, aluminum hydroxy-chloride - PAC), due to the efficiency in removing solids and low cost. However, the inorganic sludge generated after treatment may provide soluble ions that can cause environmental problems and of human health. Thus, the use of natural coagulants, such as tannin, promotes the treatment of water and wastewater and generates an organic sludge that provides greater simplicity in its handling. Organic coagulants such as tannin may be used in processes for water treatment plants with the aim of removing the turbidity. Tannins are biodegradable phenolic natural compounds obtained from the bark of the Acácia Negra tree (Acacia mearnsii), which has high concentrations of tannins and which is largely grown mainly in the state of Rio Grande do Sul. This study determined the best dosage for the acácia negra tannin and aluminum sulphate in the treatment of water from a stream of Agudos, SP. In laboratory tests, we evaluated dosages of 0, 10, 15 and 20 mg L-1 of acácia negra and aluminum sulfate. The effectiveness of treatment was measured by turbidity and residual color, coagulant activity and turbidity removal efficiency. The best concentrations for coagulation of the water samples were analyzed at 10 mg L-1 for acácia negra and 15 mg L-1 for aluminum sulphate, for removal gave 83.9% and 50%, respectively, turbidity, and promote effluent color approximately 140 uC. It is concluded that the use of coagulant from acácia negra shows superior efficiency to aluminum sulphate in water treatment.