Rapid quantification of polyhydroxyalkanoates (PHA) concentration in activated sludge with the fluorescent dye Nile blue A

摘要

The present study was conducted (1) to develop a rapid quantification method ofnpolyhydroxyalkanoates (PHA) concentration in activated sludge by Nile blue A staining andnfluorescence measurement and (2) to perform on-line monitoring of PHA concentrations in activatednsludge. Activated sludge samples collected from laboratory scale sequencing batch reactors and fullscalenwastewater treatment plants were stained with Nile blue A and their fluorescence intensitiesnwere determined. There was a high correlation (R2>0.97) between the fluorescence intensities ofnNile blue A and PHA concentrations in activated sludge determined by gas chromatography. The Nilenblue A staining and fluorescence measurement method allows us to determine PHA concentrationsnin activated sludge within only five minutes and up to 96 samples can be measured at once by usingnmicroplate reader. On-line monitoring of PHA concentrations in activated sludge was achieved bynusing a fluorometer equipped with a flow cell and the time point at which PHA concentration innactivated sludge reached the maximum level could be identified. In addition, we examined theninfluence of pH, floc size and co-existing chemicals in activated sludge suspension on thenfluorescence intensities of Nile blue A.