Evaluation of a Full-Scale Activated Sludge Real Time Control System

In the past few years both power and chemical costs have increased considerably. In the UK, commercial power costs have increased from 4.5p/kWh to 7.5p/kWh within a year and future power cost inflation is expected to be at least 11% per annum. The water industry constantly has to meet increasingly stringent discharge consents within smaller site footprints and on this basis water utilities are increasing the use of the energy intensive activated sludge processes (ASP). Recent trials conducted by MWH at a 250,000 population equivalent ASP on the south coast of the UK show that the implementation of Real Time Control (RTC) for both aeration and methanol dosing control can significantly reduce the operating cost of the activated sludge process whilst still delivering the required effluent quality. Initial results show a consistent reduction in aeration costs of 20 % with a corresponding reduction in methanol cost of 50 %.