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.
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