Otimização do processo de coagulação de águas superficiais com metodologia de superfície de resposta: estudo de coagulantes inorgânicos para remoção de cor, turbidez e UV 254

Abstract

The performance of inorganic coagulants has been studied to optimize the coagulation of surface waters. The degradation of water quality in sources intended for public supply and the need to meet an increasingly demanding potability standard are challenges to be overcome by sanitation companies in the context of water treatment. Optimizing coagulation brings several benefits to the treatment process, from cost reduction to the production of safe water. The classic method used for optimization involves changing one process variable at a time, which is time-consuming and expensive. The response surface methodology (MSR) allows experiments to be carried out in a wide variety of conditions, while reducing the total number of tests required, building models with precision, enabling agile and assertive responses for decision making, saving human resources and materials and increasing operational efficiency In this work, the surface water coagulation process was optimized with MSR for simultaneous removal of color, turbidity and UV 254 and determination of coagulation pH, evaluating the performance of three inorganic coagulants. A central rotational composite design was used to describe the dependence of the coagulant and alkalizer dosage variables on the removal of color, turbidity and UV254. The data obtained was analyzed by the protimiza software, which also determined quadratic models, verified by analysis of variance, and generated response surface graphs. The models achieved accuracy above 90%, demonstrating their adjustment to the coagulation process and were validated by triplicate tests. The Deserability function established the optimal dosages for simultaneous optimization. It was found that ferrous PAC achieved the highest removals with lower dosages, compared to aluminum sulfate and ferric sulfate. The optimized dosages of coagulant and alkalinizers in mg/L were, respectively, 78 and 0.5 for PAC; 105 and 68 for ferric sulfate and 105 and 29 for aluminum sulfate, corresponding to residuals of approximately 19; 1 and 0.1 for color (mg/L Pt-Co), turbidity (uT) and UV254 (m-1), respectively. MSR has been validated as a useful tool in ETAs, offering agile responses with resource savings.