In this research, two activated sludgeexperimental laboratoryplants were
constructed and operated using dairy wastewater. One of these plants were operated
at high temperatures of (40 – 60 oC) “Thermophilic microorganisms reactors",
whereas the other one were operated at constant temperature of (25 oC)“Mesophilic
reactor”. The resultsshowed that the organic removal efficiency of "Mesophilic
reactor" was more than the "Thermophilic reactors" and it decreasedwith increasing
the temperature.The kinetic parameters for the both mode of operations were also
calculated. The value of the substrate removal rate constant (k) for the "Mesophilic,
25ºC" reactor was (0.017 day-1) and it was greater than others for the thermophilic
reactors.(k) and (Y) decreased with increasing the temperature. The values of (Ks),
(Umax), and (Kd) in the thermophilic reactors were more than the corresponding values
in the mesophilic reactor and increased with increasing the temperature.