Interpretation of activated sludge plant performance data

Abstract

Full‐scale data obtained from a municipal activated sludge plant over a period of one year were analysed to interpret effluent quality variations and kinetic relationships using mechanistic models. It has been found that effluent quality in terms of BOD, or COD concentrations is directly proportional to the F/M loading and inversely related to the SRT. As such, effluent quality deteriorates as F/M is increased or SRT is decreased. An F/M ratio of 0.4 and SRT value of 5 days can produce adequate effluent BOD₅ concentration to satisfy regulatory requirements. The plant performance data is better fitted to a plug‐flow kinetic model than a CSTR model since the aeration basins used are of a baffled‐channel type. The biochemical reaction rate constant could be interpreted by an Arhenius plot.

Key words:

• Activated sludge plants
• effluent quality
• Kinetic models
• temperature effect