Abstract: | This study demonstrates, for the first time, that the presence of suspended solids in waste‐activated sludge interferes with adenosine triphosphate (ATP) bioluminescence tests. The sludge subject to acid/alkaline treatment represented the test sample. Without consideration of the effect of solid concentrations, one would erroneously estimate the density levels of heterotrophic bacteria in the sludge using ATP data. A light blockage model was proposed to evaluate the luminescence reading without the interference of suspended solids. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 469–474, 2001. |