A new one-dimensional clarifier model - verification using full-scale experimental data

Abstract

A new one-dimensional clarifier model was developed, including components of existing models, and extended with a height-dependent cross-sectional area and two flowrate-dependent dispersion coefficients. This model is evaluated using data from a detailed one-month measuring campaign on a full-scale wastewater treatment plant. The data included hourly sludge concentration profiles, sludge bed heights at 10 minute intervals, sludge concentrations in inlet, effluent and recycle flows and regular settling properties characterised by batch settling tests. Due to the poor quality concentration measurements at the surface of the clarifier, the model was not calibrated to perform well in concentration predictions at this surface. However, excellent descriptive capabilities were obtained for sludge profiles and blanket level. The Cho et al. settling velocity function was found to be significantly better in terms of description capability than the more traditional Vesilind function.

Mathematical Modelling and Computer Simulation of Activated Sludge Systems

“…The comparison did not include the Cho ("hybrid Vesilind ") model (Table 2.13) and the values of r f and r h parameters found by Grijspeerdt et al (1995) were rather close to each other (0.4-0.6 vs. 1.0-2.2) indicating that both exponential terms interfere with each other over a relatively broad range. In another comparative studies, Vanderhasselt andVanrolleghem (2000), andDe Clercq et al (2003) found that model to be more effective compared to the Vesilind and Takacs models in fitting the observed settling curves. It should be realised, however, that special care must be taken when using the Cho model at lower solids concentrations.…”

On-line monitoring equipment for wastewater treatment processes: state of the art

“…Left: entire sensor. Right: enlarged section of the tip region (Larsen et al, 2000) full-scale wastewater treatment plant, providing hourly measurements of concentration profiles in the settler (De Clercq et al, 2002b). A different set-up consists of three turbidimeters located at fixed but different depths in the clarifier.…”

“…From the resulting sludge sedimentation curve, the maximum sedimentation velocity and the sludge volume index (SVI, SSVI or DSVI) can be readily obtained. In addition, a sludge concentration Figure 14 Measured sludge profile versus time (De Clercq et al, 2002b) measurement can be installed in the sensor and an automatic dilution system has been tested as well.…”

Multicausal Analysis on Water Deterioration Processes Present in a Drinking Water Treatment System

“…In summer, a rise in water turbidity, which has led to deterioration in overall water quality, has been widely observed in the settling tanks of a drinking water treatment system in northeast China. To fully understand the sedimentation processes occurring in the settling tanks, computational fluid dynamics (CFD) models, such as one-dimensional (Dupont and Dahl, 1995;De Clercq et al, 2003;Plósz et al, 2007), twodimensional (Lainé et al,1999;Goula et al, 2008b), and threedimensional (Wang et al, 2008) numerical simulations, have been well developed for the application. In addition, analytical techniques,including particle image velocimetry (PIV) (Kim et al, 2003) and imaging spectroradiometer surface reflectance systems employed under a spectral unmixing model (Alcantara et al, 2010),are used during process evaluation.…”