AbstractA simplified suspended growth integrated system with an anaerobic zone in front of the aerobic one was used for the development of the bacteriumAcinetobacterfor phosphorus removal. The pilot plant experimental equipment was built at the Prague municipal works. The tests were carried out on a comparative basis, the control system was operated as a completely mixed activated sludge process. In the integrated system a to phosphate removal of 80 to 86% was achieved only in a biological way. In the control system, there was no development ofAcinetobacterand the biological phosphate removal was only 5%. To rise it to the extent comparative with the integrated system, high doses of ferric chloride for a simultaneous precipitation of phosphate were required.The results obtained showed that the strictly biological process in the integrated system could meet normal practice requirements, even though it is not able to compete with the simultaneous phosphate precipitation using high coagulant dosages as for as the attainable efficiency and higher values of the sludge index are concerned.