Authors:H. Ortiz-Oliveros, R. Flores-Espinosa, H. Jiménez-Domínguez, M. Jiménez-Moleón and D. Cruz-González
Preliminary testing of dissolved air flotation (DAF) for wastewater treatment is presented. A combined coagulation-flocculation/DAF
column system is used to remove oil and 60Co from nuclear industry wastewater. In this work, operational conditions and coagulant/flocculant concentrations are optimized
by varying pH. Determinations of air-solids ratio (G/S), retention time (θ), pressure (P), volume of depressurized air–water mixture (V), turbidity and 60Co concentrations are reported. The effect of the treatment on the efficiency of separation of oily residues is also discussed.
The results establish that the coagulant/flocculant system, formed by a modified polyamine (25 mgL−1) and a slightly cationic polyacrylamide (1.5 mgL−1), under specific operational conditions (pH = 7, mixing intensity Im1 = 300 s−1 and Im2 = 30 s−1), allowed the destabilization of colloidal matter, resulting in resistant flocs. It was concluded that by using G/S = 0.3, θ = 15 min, P = 620 kPa and V = 0.0012 m3, the greatest percentage removals of oil, turbidity, total cobalt and 60Co were obtained. These preliminary results then show that dissolved air flotation represents a good alternative for treatment
of nuclear industry wastewater contaminated with radionuclides.