Figure 4: Inactivation rates of E. coli, of fecal coliforms and of P. aeruginosa (log reduction), following UV irradiation at the depth of 150 cm in the center and in the periphery of the basin and at different UV dose. y: Reduction = N/N0 with N; Number of micro-organisms at the instant T; N0; Number of micro-organisms at the instant T= 0; Dose (mW. s. cm-2) = UV Intensity (mW. cm-2). Time of contact (s).