Treatment optimization of greywater from the combined use of chemical coagulants

ABSTRACT With the growing demand and shortage of water, efforts are needed to enable alternative sources of supply. Thus, this work was focused on optimizing the treatment of greywater by associating the chemical coagulants aluminum sulfate and ferric chloride, to enable their reuse. Therefore, the research was divided into three stages: characterization greywater from basin and shower of a single-family residence; assessing the combined use of aluminum sulfate and ferric chloride, prepared in 5% solution for the treatment of greywater, optimizing the concentrations of chemical coagulants applying Central Composed of Rotational Design and evaluating the data via Methodology Surface Response and Global Desirability; and evaluating the effectiveness of the proposed treatment, comparing the optimum dosages determined with laboratory tests. The results indicated that the combination of aluminum sulfate (concentration 0.470 g.L-1) and ferric chloride (concentration 0.115 g.L-1) potentiated treatment, achieving a removal of greywater turbidity of up to 94%; also, thermotolerant coliforms and residual chlorine were reduced, making it possible to reuse them in the discharge of toilets and in irrigation.