Evaluation of quicklime incorporation in bench-scale and full-scale lime stabilized biosolids using a flat surface pH electrode.

Journal Article (Academic article)

Uniform lime incorporation into sewage sludge is critical for biosolid lime stabilization processes. There is no class B biosolids regulation for lime incorporation. The slurry method is currently used to evaluate the pH of limed biosolids, but this method homogenizes the biosolids and potentially masks poor lime mixing. In this study, a flat-surface pH electrode was used in bench-scale and full-scale experiments to measure the pH of lime-stabilized biosolids without creating slurries. The standard deviation of 15 pH measurements at different locations in a biosolid sample was used to assess mixing quality. The bench-scale experimental study showed that well-mixed limed biosolids had consistently high pHs (approximately 12) with low standard deviations ( 2 pH units). Poorly mixed biosolids exhibited rapid and marked pH reduction, as well as offensive odor generation, whereas well-mixed biosolids resisted pH reduction and offensive odor generation. The full-scale study aimed at improving lime incorporation and biosolids quality confirmed the use of a flat surface pH electrode to capture low pH regions in biosolids that were masked by the current slurry method.

Duke Authors

Cited Authors

  • Burns, B; Krach, K; Cole, C; Mangus, J; Butler, H; Li, B

Published Date

  • July 2007

Published In

Volume / Issue

  • 57 / 7

Start / End Page

  • 794 - 802

International Standard Serial Number (ISSN)

  • 1096-2247

Conference Location