Esfandiar Jalilzade - Reference Laboratory in water and wastewater Co. Dr Fatemi Ave, Tehran, Iran.
Fatemeh Houshmand - K.N.Toosi University of technology, Dr. Shariati Ave, Kavian Ave, Tehran, Iran.
Sharare Shamloi - Reference Laboratory in water and wastewater Co. Dr Fatemi Ave, Tehran, Iran.

Using the MIMS and DPD/FAS titrimetric methods the chlorination of Vibrio Cholera and thermo-tolerances coliforms suspensions were applied for determining the critical chloride concentration. Samples were prepared from 7 (T-Z) wastewaters plants effluent in Tehran province during 3 years. Different patterns of residual chlorine distribution were found in the chlorine-decay kinetic portion of the study

Vibrio cholera, chlorine, chloramine, DPD/FAS, organic-N