SAFEGUARDING ACTIVATED SLUDGE SYSTEM -SLUDGE REDUCTION AND EFFICIENCY- (Published)
Activated sludge system is the most widely used biological process for the treatment of wastewater. One problem associated with this process is related to the amount of excessive sludge produced which requires further treatment and disposal. Current methods for dealing with this sludge include disposing to landfills, recycling as a soil fertilizer and incineration. All of which considered to be costly options due to advanced treatment requirements related to tightened regulations and environmental measures placed on the outlets. In this essence, estimation of sludge production amounts has come to the forefront. The current practice in performing the mass balance around the Activated Sludge system only considers the steady state scenario and neglects the Secondary Clarifier (SC) dynamic state. In particular, the determination of sludge height is not accurate as it is predicted based on the visible depth measurements. Under such condition, the solids accumulation in the SC is usually not accounted for in the mass balance calculations. This paper will address the impact of actual sludge height rather than visible depth on the activated sludge mass balance. Further, this study suggests a scenario of reducing the wasted activated sludge in an attempt to improve the SC functioning, reduce the disposal cost while, safely operating the SC. The required data were collected from a Wastewater Treatment Plant over a seven months period, representing sludge height measurements using both manual and automatic sludge depth detector. Results presented in this paper provide a better understanding of the SC performance; as mass balance can be accurately drawn and the SC safety margin can be exactly determined. In addition, the laid out scenario will enhance the SC performance in terms of settling properties, reducing the excessive sludge while, maintaining almost the same effluent characteristics
Keywords: Activated sludge, Sludge height, Sludge reduction, Wastewater treatment plant