Abstract
Particle fractions of 100-200, 10-100 and <10μm were separated from secondary effluents by plankton nets. Indigenous fecal coliforms associated with each particle size fraction were tested for their resistance to chlorine individually. Particle-associated fecal coliforms of the <10μm fraction were inactivated more rapidly by 0.5 and 1.0mg of chlorine per liter at 25°C and pH 7 than the other fractions. Contact times required for 99.9% inactivation of 0.5mg of chlorine per liter were over 3 -fold greater than the case of 1.0mg in each particle size fraction respectively. It is suggested that fecal coliforms associated with particle in actual secondary effluents have an aprotective effect against the disinfecting action of chlorine. And, it is demonstrated that many injured cells were yielded by chlorination in which are possible to rOcover in an adequate situation.
