Fig. 2 shows the efficiency of peractic acid on E. coli and S. aureus when in suspension. When E. coli was treated with peracetic acid solution at 60 mg/L at 25ºC, a reduction of 8.0 log cycles was attained in 3.1 minutes of contact. When the concentration of the peracetic acid solution was reduced to 40 mg/L, 4.0 minutes were necessary to attain the same destruction level. S. aureus was more resistant than E. coli. For this microorganism and a peracetic acid solution at 40 mg/L, only 6.2 log cycle reduction was achieved in 10 minutes of contact. Fig. 2 also shows that the destruction kinetics can be represented by first order equations, which are shown in Table 1. This Table also shows the time necessary to attain one log cycle reduction (D values).