Experiments were conducted in the Hydraulics Laboratory of the Federal University of Lavras to determine the head loss and the friction coefficients of the Universal and Hazen-Williams equations in PVC commercials pipes conducting wastewater of coffee processing. The results indicated an increase of the attrition " factor f " and, consequently, of the head loss, from 5 to 35% for despulping wastewater, and from 2 to 11% for peeling wastewater in relation to water, for pipes of 75 and 25 mm respectively; the load loss decreased with the dilution of the wastewaters; the coefficient "C" of the Hazen-Williams equation varied from 125 (despulping wastewater and diameter 25 mm) to 148 (peeling wastewater and diameter 75 mm).
friction coefficient; peeling; despulping
