The effect of temperature on the growth and biochemical activities of Escherichia coli in sewage

Studies on the role of individual species of bacteria in wastewater treatment methods, especially the effect of environmental factors and enzyme activities, are limited. In the present investigation Escherichia coli, isolated from a stabilisation pond, was grown in sterile sewage at various temperatures, ranging from 10 degrees to 50 degrees C, and its growth and associated biochemical activities were studied. A temperature of 30 degrees C was found to be optimum for the growth, BOD removal, NH(3)-N release and the activities of protease and catalase. E. coli which was once considered to be of little value in wastewater treatment, also accounted for a considerable reduction in BOD and NH(3)-N release. At optimum and lower temperatures, the catalase activity was proportional to the viable cell count of the bacterium. Dissolved oxygen exhibited an inverse relationship with bacterial growth and protease activity was more pronounced during the declining phase of bacterial growth.