Dispersion Models for Waste Stabilization Pond: A Comparative Analysis

Abstract

Dispersion number (d) is the most basic factor of measurement in hydraulic modeling of pollution in waste stabilization ponds and its accuracy is important to measure the characteristic behavior of pollutants in the pond. Tracer experiments were performed in a laboratory channel to determine concentration of solute and dispersion number for different flows through the channel. Two methods of sample collection were adopted: (1) constant-time-variable-distance and (2) constant-distance-variable–time apperoches. Five dispersion models used in the determination of dispersion number in waste stabilization ponds namely Levenspiel and smith [1], Liu [2], Polprasert and Bhatarai, Taylor [3] and Agunwamba and Uneke [4] were used to determine the phenomena and compared. Model calculations showed that Liu’s model is closest to that of Levenspiel and Smith which is used as standard for tracer concentration measurement dispersion number in ponds. Lui’s model may then be used for design of new ponds. Agunwamba’s model follows after Liu’s in closeness but overestimates peak concentration by about 3 times the measured. It is however better than Levenspiels in that it is time saving and cost effective. Unlike Liu’s model, Agunwamba’s model cannot be used in design of new ponds.