Using the Flocculation Index to optimise coagulant dosing during drinking water treatment

Using the flocculation index to optimise velocity gradient during slow mixing in drinking water treatment

“…The study showed that tapered gradients promoted greater turbidity efficiency removal than fixed gradients even with smaller flocs. A comparison of the aggregation and breakup constants obtained for tapered and fixed gradients showed that aggregation constants for fixed gradients promoted more flocs, while lower breakup constants for tapered gradients promoted stronger and more compact flocs, which is consistent with the findings of other studies [5,15,20,21] that observed denser flocs with greater gradients. Therefore, the use of continuous flocculation monitoring equipment allows us to better understand this phenomenon.…”

“…The experiments conducted revealed several relevant discoveries. The flocculation index was shown to play a crucial role in choosing the best gradient in all the experiments, confirming the findings of other studies [17,21]. Furthermore, the utilization of CFME provided a notable deepening of the understanding of the differences in flocculation processes between tapered and fixed velocity gradients.…”

“…In fact, different authors [5,15,20,21] state that an adequate average floc size (d -Equation 1) enables the acquisition of operational conditions (dosage, coagulant, velocity gradient, stirring time) that provide better solid retention at a much faster pace than Jar Test experiments. According to Equation 1, at the same temperature and at similar fractal dimension flocs (Df), the average floc size (d) is a crucial factor for increasing the settling velocity of flocs.…”

Continuous floc image analyser (C-FIA) for tracking floc particle dynamics during coagulation–flocculation–settling processes

“…11,18,19 More recently, PDA FI was also used for coagulant dose control in coagulation process. 20 The data for FI is attained through the light intensity fluctuations (variance) as particles pass through a flow-through cell. The FI is defined as the ratio of the root mean square of the fluctuating intensity (AC value or Vrms) of the transmitted light to the average transmitted light intensity (DC value).…”

“…18 The application of PDA for tracking the degree of aggregation of flocs formed following coagulation has been extensively reported. 17,18,20 However, in practical systems, detailed visual information of flocs such as actual size, and specific number of particles cannot be readily derived through the FI data obtained by PDA, 21 even in the latest model (i.e., PDA3000, Rank Bros Ltd., Cambridge, UK). This is due to the PDA FI data being a proxy/surrogate parameter used to provide floc particle information.…”