Avaliação comparativa de agentes coagulantes químico e natural no processo de coagulação de águas servidas.

Abstract

The practice of wastewater reuse has been extensively studied and its purpose is to reduce the demand on springs due to the substitution of drinking water for lower quality water. Among the activities that use water the most, there are car and clothes washing which generate wastewater with high loads of suspended matter. One of the alternatives found for the treatment of this type of effluent is the use of coagulants. Thus, the aim of this work is to compare the applicability of aluminum sulfate and Moringa oleifera seeds in the process of coagulation wastewater from car and clothes washing. 1.0 L effluent samples were collected from a car wash and a residence located in the city of Sumé-PB and were used to perform the tests, being applied as coagulants aluminum sulfate and moringa seeds sprayed in solution. Factorial design 22 was applied with three repetitions at the central point to verify the influence of treatment time and amount of coagulants on turbidity, pH and electrical conductivity of the samples. The results obtained from the car wash effluent showed a reduction in turbidity of up to 94% when using coagulant obtained from moringa seed, and up to 96% for sulfate, which also provided a reduction in pH and increased electrical conductivity. Statistical analysis indicated that for a 95% confidence level, the effect of time was significant on turbidity response for both coagulants used. Analyzing the results obtained for the clothes washing effluent, there was a reduction in turbidity of up to 92% when using coagulant obtained from moringa seed, and up to 70% for sulfate, which also provided pH reduction. The statistical analysis results, with a confidence level of 95%, showed that, for the turbidity response, when sulfate was used, both factors and the interaction were statistically significant, while for the moringa only time had a significant effect. For the studied conditions, it is possible to state that moringa seeds can be applied as coagulant in wastewater treatment, reducing turbidity levels, with the advantage of being a low cost natural product and without promoting significant changes in pH and electrical conductivity of the samples.