Detailed spatio-temporal solids concentration profiling during batch settling of activated sludge using a radiotracer

• Published in: Water research (Oxford) Vol. 39; no. 10; pp. 2125 - 2135
• Main Authors: De Clercq, Jeriffa, Jacobs, Filip, Kinnear, David J., Nopens, Ingmar, Dierckx, Rudi A., Defrancq, Jacques, Vanrolleghem, Peter A.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.05.2005; Elsevier Science
• Subjects: Activated sludge; Applied sciences; Batch settling; Biological and medical sciences; biosolids; Biotechnology; cameras; Concentration profiles; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Gamma camera; Gamma Cameras; gamma radiation; Industrial applications and implications. Economical aspects; Isotope Labeling - methods; Mathematics; methodology; Other industrial wastes. Sewage sludge; Pilot-scale; Pollution; radiolabeling; Radiotracer; Sewage - chemistry; Time Factors; Waste Disposal, Fluid - methods; Wastes; wastewater treatment; Water treatment and pollution; Activated sludge; Concentration profiles; Batch settling; Pilot-scale; Radiotracer; Gamma camera; Modeling; Sewage treatment plant; Biological purification; Concentration measurement; Batchwise; Measurement technique; Measurement method; Waste water purification
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2005.03.023

In building and tuning good settling models for secondary clarifiers of wastewater treatment plants, there is a need for measured continuous solids concentration profiles during batch settling. Conventional measuring techniques have difficulties in recording this kind of data, either because they are invasive, or because of the low solids concentration and/or solids density of activated sludge. This paper investigates a novel non-invasive measurement technique borrowed from nuclear medicine, using a solids radiotracer and gamma cameras, to obtain solids concentration profiles during the batch settling of activated sludge, in a pilot-scale column with a height of 1 m. The technique does not disturb the settling process, does not alter the settling characteristics, gives profiles every minute and every few millimeters, and is capable of measuring in a range of 0–25 g/l with high accuracy. Dynamic solids concentration profile measurements were performed for sludges of different wastewater treatment plants, and at different initial concentrations. The results show a quantitative representation of the settling process, and reveal hindered and compression settling.