Wastewater COD characterization: Analysis of respirometric and physical-chemical methods for determining biodegradable organic matter fractions

Abstract

BACKGROUND: In this work, a comprehensive study of the respirometric and physical-chemical methods has been performed to evaluate the information provided by these two methodologies in order to assess the biodegradable organic matter fractions of wastewater. RESULTS: First, an analysis was performed of the influence of the initial substrate on biomass ratio (F0/X 0) in the assessment of readily biodegradable organic matter, S S, through respirometric experiments. In order to achieve an adequate assessment of the SS component, similar conditions (given by the initial F0/X0 ratio) must be employed in experiments that are carried to determine SS and YH (heterotrophic yield). Second, a comparative analysis of respirometric and physical-chemical methods was carried out. The respirometric analysis yielded a lower value of the S S component than the one using the physical-chemical method. Moreover, the respirometric analysis cannot measure the total content of slowly biodegradable organic matter, XS, since this method is only capable of determining the readily hydrolyzed biodegradable substrate. CONCLUSIONS: Considering the results, an adequate characterization method of the S S component has been proposed. This method provides readily and slowly hydrolyzable biodegradable organic matter fractions. © 2010 Society of Chemical Industry.