Active biomass in activated sludge: Comparison of respirometry with catalase activity measured using an on-line monitor

On-line measurements of the activity of activated sludge biomass may allow more efficient operation of treatment plants. A novel monitor for activity which can be used on-line follows oxygen evolution from hydrogen peroxide b y catalase activity in activated sludge. Results from this monitor were com pared with assays of oxygen uptake rate (OUR) by respirometry. Samples from the five activated sludge plants were assayed and showed, as expected, tha t the mixed liquor suspended solids (MLSS) and volatile suspended solids (V SS) levels were a poor measure of the activity of the sample determined by OUR. However, the activity of the biomass determined by the catalase activi ty biomass monitor correlated well with the respiration rate. This monitor should provide a simple and robust alternative to OUR measurements in activ ated sludge plants. (C) 1998 Elsevier Science Ltd. Ail rights reserved.