Development of Design Tool for Sizing of Asp using Kinetics and Performance Data from Operational Plants

Abstract

Activated Sludge Process (ASP) is one of the aerobic systems popularly used for treating wastewater with soluble BOD. Mathematical modeling of the process can help the plant operator to predict the performance of the plant and take timely remediation actions. For designing of ASP, engineers rely heavily on experience based approaches do not give due consideration to the microbial kinetics. Literature highlights the work on analysis and design of suitable model structures for optimum design of activated sludge plants, characterization of wastewater for modeling of ASP, bio kinetic coefficients determination, estimation of solids at low and high SRTs, identification of parameters for calibration of activated sludge models and performance evaluation of activated sludge units in wastewater treatment plants. In this context, an attempt is made here to optimize a link between experience based design approaches and microbial kinetics. In the present study, efforts are made to develop a design tool in MS Excel to help in deciding the sizes of components in an ASP. The prepared spreadsheet for design was calibrated with data from full scale operational plants. After calibration, sensitivity analysis was performed to study the effect of SRT and MLSS on parameters by varying one of them and keeping the other constant. Data pertaining to wastewater from food and beverage industry and municipal sewage treatment plant were used for testing the tool. The causes for deviations, if any, in the actual and predicted values were discussed and suitable recommendations were made to reduce the error.