Characterization, fate and transport of floc aggregates in full-scale flocculation tanks

Vadasarukkai, Yamuna S.; Gagnon, Graham A.

doi:10.1039/c5ew00259a

Cited by 2 publications

(4 citation statements)

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“…The major difference in the overall floc size distributions resulting at the optimal coagulant concentrations for the two pHs studied would have potential implications for a number of treatment plants. Prior investigation of the spatial distribution of floc sizes at a direct filtration plant suggests large, irregular shaped floc aggregates can reduce the effective filter run times . The data acquired in the present study on floc sizes can be calibrated to a treatment plant’s specific case by operating at a definite pH, coagulant dose, and mixing energy.…”

Section: Practical Implications For Water Treatmentmentioning

confidence: 88%

“…The formation of microflocs was not recorded at coagulation G-values >450 s −1 due to bubbles formed near the sampling port, which can cause significant errors in size measurements. Numerical reconstruction of holograms was performed to get images of floc aggregates, as described in Vadasarukkai et al 25 Equivalent circular diameter (d) of floc size was calculated from the area of the identified flocs, which was expressed as a volume-based floc equivalent diameter.…”

Section: Methodsmentioning

confidence: 99%

“…Prior investigation of the spatial distribution of floc sizes at a direct filtration plant suggests large, irregular shaped floc aggregates can reduce the effective filter run times. 25 The data acquired in the present study on floc sizes can be calibrated to a treatment plant's specific case by operating at a definite pH, coagulant dose, and mixing energy. For plants requiring dense and pinpoint flocs, such as in a direct filtration facility, a small standard deviation in floc sizes would be beneficial; this can be achieved at a slightly acidic pH condition.…”

Section: Practical Implications For Water Treatmentmentioning

confidence: 99%

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Influence of the Mixing Energy Consumption Affecting Coagulation and Floc Aggregation

Vadasarukkai

Gagnon

2017

Environ. Sci. Technol.

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The operational significance of energy-intensive rapid mixing processes remains unaddressed in coagulation and flocculation of insoluble precipitates (flocs), which play an important role in the removal of impurities from drinking water supplies. In this study, the influence of rapid mixing and associated mixing energy on floc aggregation was examined for a surface water source characterized by a high fraction of aquatic humic matter. Infrared spectral analyses showed that the colloidal complexes resulting from ligand exchange between iron and dissolved natural organic matter (DOM) were not substantially influenced by the mixing energy input. This signified that DOM removal by coagulation can be achieved at lower mixing intensity, thereby reducing energy consumption. In contrast, macroscopic investigations showed the coagulation mixing energy affected floc size distributions during the slow mixing stage in flocculation and, to some extent, their settling characteristics. The results from analysis of floc properties clearly showed that more mixing energy was expended than necessary in coagulation, which is typically designed at a high mixing intensity range of 600-1000 s in treatment plants. The key findings from this study have practical implications to water utilities to strategically meet water quality goals while reducing energy demands.

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Section: Practical Implications For Water Treatmentmentioning

confidence: 88%

Section: Methodsmentioning

confidence: 99%

Section: Practical Implications For Water Treatmentmentioning

confidence: 99%

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Influence of the Mixing Energy Consumption Affecting Coagulation and Floc Aggregation

Vadasarukkai

Gagnon

2017

Environ. Sci. Technol.

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“…is process is called coagulation, which has typical timedelay and nonlinear characteristics [1][2][3]. With the development of computer technology, the method of using image processing technology to detect the shape of floc particles and extract the characteristic parameters of floc particles has gradually become a current research focus [4] to control the coagulant dosage.…”

Section: Introductionmentioning

confidence: 99%

Optimal Calculation Method of Mean Equivalent Diameter of Floc Particles Based on MCC

2022

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In the process of water treatment, coagulation is an important process to remove minerals and organic particles from raw water, which has typical time delay and nonlinearity. The effect of coagulation directly affects the turbidity of the effluent. According to the good correlation between the mean equivalent diameter of floc particles and the turbidity of effluent water, the image processing method is used to preprocess the floc image, the parameters of floc particles are quantitatively analyzed, and the mean equivalent diameter of floc particles is obtained, which is used as one of the bases for the control of coagulant dosage. However, no matter whether the coagulation process in actual situations interferes with the outside world or not, the equivalent diameters of floc particles after coagulation may have abnormal and invalid values, which may lead to a problem that there is a large difference between the mean equivalent diameter of floc particles calculated by a least square method and the mean valid equivalent diameter of floc particles. In response to this problem, this article proposes an optimal calculation method of the mean equivalent diameter of floc particles based on the maximum correntropy criterion (MCC) to reduce the negative impact of the abnormal and invalid equivalent diameters of floc particles on the mean equivalent diameter and provide an important reference data for the precise dosing control of coagulants. Finally, the feasibility of the theoretical results is verified by several numerical experiments.

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Characterization, fate and transport of floc aggregates in full-scale flocculation tanks

Abstract: In-line measurements of floc size distributions at different locations in a hydraulic flocculation tank using a holographic microscopy.

Cited by 2 publications

References 28 publications

Influence of the Mixing Energy Consumption Affecting Coagulation and Floc Aggregation

Influence of the Mixing Energy Consumption Affecting Coagulation and Floc Aggregation

Optimal Calculation Method of Mean Equivalent Diameter of Floc Particles Based on MCC

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