One of the viable alternatives for the sustainable use of water resources is the reuse of
greywater for non-potable purposes. Among the greywaters, those coming from washing
machines are those that present the easiest treatment due to their physical, chemical and
microbiological characteristics. This study estimated the amount of greywater generated
monthly in the Palmas-TO laundries, characterized the greywater generated in this activity,
evaluated alternatives for the treatment of greywater from laundries aiming at reuse in nonpotable
purposes, and framed its characteristics after treatment legislation requirements for
the reuse of treated greywater. Bench tests were performed simulating three greywater
treatment processes: a) sand filter filtration; b) coagulation, flocculation, sedimentation and
filtration on a sand filter and c) coagulation, flocculation, sedimentation, filtration on a sand
filter and activated carbon filter filtration. Treatment tests were performed in jar-test using the
aluminum sulfate coagulant and to optimize this process the factorial designs were made:
fractional factorial design (DFF), central composite design (DCC) and rotational central
composite design (DCCR). The results of bench tests showed that sand filtration alone is not
sufficient for greywater from laundry to be reused in classes defined by the National Water
Agency (ANA) and the Brazilian Association of Technical Standards (ABNT), but when
subjected to sand filter coagulation, flocculation and filtration followed or not by activated
carbon filter filtration, greywater from laundry becomes suitable for reuse in some of the
classes defined by ANA and ABNT. Favorable nutrient removal results were achieved with the
applied treatments, such as 98.8% and 99.3% turbidity removal in the sand filter and sand filter
filtration followed by activated charcoal filtration respectively and COD of 73.1% and 89.5%
when also submitted to these treatments. Total solids removal was 66.3% and 80.9% total
coliforms were removed. The results show that the treatment of greywater from laundry and its
reuse in non-potable purposes is feasible. Therefore, full scale studies are indicated to validate
the parameters obtained.
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