In-line rheological characterisation of wastewater sludges using non-invasive ultrasound sensor technology

Abstract

The performance of a new ultrasound transducer, which can measure velocity profiles non-invasively through high-grade stainless steel pipes, was evaluated for the first time with secondary wastewater sludges. This work is a follow-up study on the feasibility work initially done by the same authors. In-line process control based on accurate rheological characterisation for treated wastewater sludge could lead to significant savings in chemicals and will optimise dewatering processes producing drier sludges. In this work, a wastewater sludge at three concentrations was tested in order to investigate the capabilities of the in-line ultrasound technique for different viscosities and fluid properties. The rheological parameters obtained using the new ultrasound sensor and ultrasonic velocity profiling with combined pressure difference (UVP + PD) technique were compared with results obtained using conventional tube viscometry. Comparison with tube viscometer results showed that yield stresses could be overestimated by 120% if data are not available in the low shear-rate ranges. This non-invasive transducer proved to be sensitive enough to obtain flow curves over a large shear-rate range, improving the prediction of the yield stress and requiring about 50% less energy than the invasive system.

Shear and extensional rheology of commercial thickeners used for dysphagia management

“…The real‐time velocity profile was monitored with advanced tube viscometry using PUV + PD measurement to acquire the flow curve (Flow‐Viz, Gothenburg, Sweden). The method and the system are described in detail elsewhere (Kotzé, Haldenwang, Fester, & Rössle, ; Wiklund, Shahram, & Stading, ; Wiklund & Stading, ). In the present study, the sample was mixed in the product tank with an agitator (Figure ).…”

Low yield stress measurements with a microfluidic rheometer

“…This becomes even more advantageous when these measurements are conducted in real-time. [39][40][41][42][43] For instance, in the food industry, real-time measurement of τ y could serve as a valuable tool for monitoring product quality.…”

P1.10 - Ultraschall – Etablierte Methodik oder innovative Messtechnik?

“…Gerade der Einsatz von Ultraschalltechniken hat sich in verschiedenen Bereichen der Prozessüberwachung in den letzten Jahren deutlich erhöht. Im Vergleich zu anderen vorhandenen Techniken bietet Ultraschall eine schnelle, kostengünstige und nicht-destruktive Methode zur Analyse von Prozess-und Produktparametern [4][5][6]. Durch ihren nicht-invasiven Charakter bieten sich vielfältige Anwendungsgebiete, gerade in den produktsensiblen Prozessschritten der Life Sciences [7][8][9] und der Lebensmittelindustrie [10][11][12].…”