Density and sludge volume index estimation in mature aerobic granular sludge by quantitative image analysis and chemometrics tools

Abstract

Quantitative image analysis (QIA) has already been applied for activated sludge dysfunctions and anaerobic granular sludge processes elucidation and its application to aerobic granular sludge characterization is considered of major interest. In this work, a sequencing batch reactor (SBR) was operated using mature aerobic granular sludge for pharmacologically active compounds (PAC) removal. The physicochemical parameters (total and volatile suspended solids, sludge volume index and density), prior to the introduction of PAC, were determined by analytical methods. The mature aerobic granular and suspended sludge morphological and structural parameters were established by QIA. The objective of this study is to characterize this mature granular sludge by QIA, and establish relationships for physicochemical parameters (aggregates density and SVI30) with QIA data using chemometric tools. Indeed, relevant relationships could be found for both density (R2 of 0.81) and SVI30 (R2 of 0.87).