TREATMENT OF EFFLUENTS FROM DEEP STABILIZ ATION POOLS BY COAGULATION-FLOCCULATION

It has been applied the physicochemical treatment of coagulation-flocc ulation to the effluent of a deep pool full of stabilized residual wat er, in order to reduce its content in dissolved solids and therefore, in organic matter in solution and in colloidal state. For the control of this treatment efficacy there have been chosen the following method s: Oxygen Biochemical Demand after five days (DBO5) and Total Dissolve d Solids (SST). The coagulants used in the tests were the following: F e-2(SO4)(3), FeSO4 . 7H(2)O and Al-2(SO4)(3) . 18 H2O. It has been stu died the process efficacy with regard to the coagulant dose, pH and se dimentation time. In optimum conditions, DBO5 removal efficiency was: 80% for Fe-2(SO4)(3), 85% for FeSO4 . 7H(2)O and near 100% for Al-2(SO 4)(3) . 18 H2O; and the SST removal efficiency was: 90% for Fe-2(SO4)( 3); 65% for FeSO4 . 7 H2O and 85% for Al-2(SO4)(3) . 18 H2O.