Effect of the micro-flocculation stage on the flocculation/sedimentation process: The role of shear rate

Wang, Zhenbei; Nan, Jun; Ji, Xiaoyu; Yang, Yueming

doi:10.1016/j.scitotenv.2018.03.286

Cited by 61 publications

(23 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We observed that several polycationic skeletons [e.g., polydimethyldiallylammonium chloride (PDMDAAC)] contained the high densities of cationic adsorption points which could produce efficient electrostatic attractions (i.e. ionic bonds) towards the coloured anionic dyes, [20][21][22][23][24][25][26][27][28][29][30] when they were incorporated into cotton skeletons, to obtain a series of new polycationic cotton adsorbents reported in our previous serial works. [31][32][33] It was observed that the adsorption capacities of all the polycationic cotton adsorbents were improved 17.…”

Section: Introductionmentioning

confidence: 99%

Homologous–heterogeneous structure control and intelligent adsorption effect of a polycationic gel for super-efficient purification of dyeing wastewater

Song

2019

RSC Adv.

View full text Add to dashboard Cite

show abstract

Section: Introductionmentioning

confidence: 99%

Homologous–heterogeneous structure control and intelligent adsorption effect of a polycationic gel for super-efficient purification of dyeing wastewater

Song

2019

RSC Adv.

View full text Add to dashboard Cite

show abstract

“…(2) Flocs are joined together with the others (cluster) forming links or bridges between the flocs. In other studies, the behavior and relevance of flocs in different processes can be seen [1][2][3][4][5][6] as well as the effect of coagulation and filtration in water treatments [7].…”

Section: Introductionmentioning

confidence: 99%

Characterization of Filamentous Flocs to Predict Sedimentation Parameters Using Image Analysis

2020

View full text Add to dashboard Cite

In wastewater treatment plants, the degradation of complex substances that contaminate water is carried out by microorganisms, which are fixed by a network formed by filamentous bacteria, creating large flocs that settle easily. However, the excessive growth of said bacteria causes a series of drawbacks such as the reduction of settling velocity, leakage of activated sludge with the effluent, and formation of supernatant, a phenomenon known as bulking. This research work seeks to develop and evaluate a procedure for the physical characterization of the flocs to determine the parameters that affect the settling velocity and thereby detect and control bulking. For this purpose, sedimentation and image analysis tests were carried out from wastewater from the Aguas Antofagasta treatment plant (Chile). The image analysis was performed with images captured from an optical microscope in two magnifications (100x and 50x), which were analyzed by marking each floc individually and characterized by an image processing software. Additionally, sedimentation tests were performed on columns (area of 74 (cm2) and height of 70 (cm)). As a result, an inversely proportional dependence was found on the settling velocity evaluated by the Vesilind equation in the zone of constant fall velocity with respect to the number of flocs connected per cluster, giving an estimate of the settling velocity depending on the number of flocs connected. This would allow predicting settling velocity with image analysis, taking into account that the problem of bulking is determined by the type of filamentous bacteria that causes it and the sedimentation process is affected in large part by local factors. It can be concluded through this study that as the number of flocs connected per cluster increases, the settling velocity decreases. This study provides wastewater treatment plants with a practical tool to determine sedimentation times and thus improve the quality of the treated water, avoiding problems of flocs leaking with the effluent. In addition, the image analysis itself allows rapid detection of the phenomenon of bulking and its severity.

show abstract

“…Shear breakage and reflocculation are of great significance for controlling the structure, settling, and dewatering of flocs , Li et al, 2017, Ofori et al, 2011, Xu and Gao, 2012. However, most previous studies have focused on the flocs of clay (Wang et al, 2018), wastewater (He et al, 2018), soil sludge , oil sands tailings (Wang et al, 2014), or other minerals (Yin et al, 2011). Relatively little research has been conducted on the floc of coal tailings.…”

Section: Introductionmentioning

confidence: 99%

Effect of shear-induced breakage and reflocculation on the floc structure, settling, and dewatering of coal tailings

Fan

Song

et al. 2020

Physicochem. Probl. Miner. Process.

View full text Add to dashboard Cite

Flocculation is crucial for the treatment of coal tailings in industries. In this paper, the effects of shear-induced breakage and reflocculation of the floc, settling, and dewatering of coal tailings were investigated. The results show that as shear strength increases, the settling velocity of flocculated tailings decreases. A shear rate of 200 rpm (170.6 s -1 ) leads to the loss of half the settling velocity. However, at high dosage cases, 200 rpm-300 rpm shear could improve the clarity of the supernatant. Small particles are flocculated preferentially, especially for particles below 10 µm. With the increase in dosage, the critical particle size for the occurrence of flocculation increases. The chaos index proposed can quantitatively reflect the degree of flocculation or reflocculation of coal tailings. At high dosage conditions, shear could enhance the dewatering performance of flocs by reconstructing the filter cake. Controlling the structure of flocs by dosage and shear strength can help obtain appropriate settling, clarifying, and dewatering performance of coal tailings.

show abstract

Effect of the micro-flocculation stage on the flocculation/sedimentation process: The role of shear rate

Cited by 61 publications

References 46 publications

Homologous–heterogeneous structure control and intelligent adsorption effect of a polycationic gel for super-efficient purification of dyeing wastewater

Homologous–heterogeneous structure control and intelligent adsorption effect of a polycationic gel for super-efficient purification of dyeing wastewater

Characterization of Filamentous Flocs to Predict Sedimentation Parameters Using Image Analysis

Effect of shear-induced breakage and reflocculation on the floc structure, settling, and dewatering of coal tailings

Contact Info

Product

Resources

About