Evaluation of the operation performance of a municipal activated sludge unit

Abstract The objective of this work was the evaluation of the operation of a municipal activated sludge unit and the assessment of potential correlations between the operating parameters that might affect the process performance. Samples were collected from various points of a plant receiving about 40,000 m3 day−1 and were analyzed for the determination of a number of parameters. The assessment of the effluent parameters and the statistical evaluation of the values during an one year monitoring period proved an efficient operation of the plant, resulting to an effluent of low organic loading and nitrogen concentration. COD average values did not exceed 60 mg l−1, while maximum values remained always lower than 95 mg l−1. These parameters remained almost constant during the monitoring period, and were not affected by potential variations of influent characteristics. The assessment of the activated sludge process took place by the measurement of the mixed liquor suspended solids and the sludge volume index;...