New monitoring methods are required to enhance the operation of a wastewater treatment process and to meet the constantly tightening regulations for the effluent discharges. An on-line optical monitoring device, that analyses the morphological parameters of the flocs, has been shown to be a potential tool for assessing the wastewater quality and the state of the activated sludge process. In this paper, the earlier presented trend analysis method is applied to the operating conditions, the treatment results and the optical monitoring variables of a full-scale biological wastewater treatment process. The trend episodes and the deviation indices resulted from the trend analysis provide warning of the changes in the monitored variables and the received information can be used as assistance in the treatment process operation and avoiding harmful environmental risks.
Keywords: Activated sludge; morphology; nonlinear; operation conditions; optical monitoring.