Evaluation of floc strength by morphological analysis and PDA online monitoring

This paper established a method for the evaluation of floc strength by morphological analysis and PDA online monitoring. Theoretically, the binding force of a floc can be expressed as B=k1d2Df/3, where k1 is a coefficient, d is floc size and Df is the fractal dimension of the floc. In order to calculate the binding force under a given flocculation condition, a jar test was conducted and d and Df were measured by image analysis. A shear force was exerted on the grown flocs by introducing the flocculated suspension through a transparent tube where the velocity gradient value of the flow could be accurately controlled. As the tube was connected with a particle dispersion analyzer (PDA), the condition of floc breakage was online monitored and the critical condition was identified by analyzing the PDA outputs (FI curves). The binding force coefficient k1 could thus be determined, and the binding force B which represented the floc strength was evaluated. The validity of this method was proved by a series of experiments using aluminium sulphate as coagulant for the flocculation of humic substances.

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On the Strength and Character of Alumino-Humic Flocs

Water Science & Technology ◽

10.2166/wst.1999.0448 ◽

1999 ◽

Vol 40 (9) ◽

pp. 81-88 ◽

Cited By ~ 22

Author(s):

D. H. Bache ◽

E. Rasool ◽

D. Moffat ◽

F. J. McGilligan

Keyword(s):

Particle Size ◽

Continuous Flow ◽

Structural Model ◽

Bonding Mechanism ◽

Aluminium Sulphate ◽

Floc Size ◽

Physically Based ◽

Floc Strength ◽

Series Of Experiments ◽

Equivalent Conditions

The paper describes the size, density and strength of flocs gained from a humic acid suspension coagulated with aluminium sulphate over a range of dose and pH. Flocs were generated on a continuous flow basis in an oscillatory mixer. Particle size measurements were gained using CCTV and image analysis. From this, a maximum floc size (d95) was identified. A second series of experiments examined the floc sizes of the bulk precipitate alone under equivalent conditions. It was found that the overall floc sizes of the two suspensions were broadly similar, suggesting that the floc strength was dominated by a common bonding mechanism irrespective of the presence of the humic colloids. Some features of the size distribution in response to dose and pH were attributed to the influence of surface charge. Upper floc sizes were proportional to the Kolmogorov length (η) with d95/η ∼1. For typical levels of mixing, the floc strength was estimated to be on the order of 0.1 N m−2. By analysing the breakage kinetics in energy terms and relating the strength to the density of individual floc, a physically-based structural model was developed to explain the response of the floc size to the prevailing state of mixing.

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Control of coagulation process by dual wavelength article analyzer

Water Science & Technology ◽

10.2166/wst.1997.0104 ◽

1997 ◽

Vol 36 (4) ◽

pp. 135-142 ◽

Cited By ~ 2

Author(s):

Norihito Tambo ◽

Yoshihiko Matsui ◽

Ken-ichi Kurotani ◽

Masakazu Kubota ◽

Hirohide Akiyama ◽

...

Keyword(s):

Water Quality ◽

Control System ◽

Predictive Control ◽

Control Method ◽

Feedforward Control ◽

Raw Water ◽

Floc Size ◽

Coagulation Process ◽

Series Of Experiments ◽

Size Data

A coagulation process for water purification plants mainly uses feedforward control based on raw water quality and empirical data and requires operator's help. We developed a new floc sensor for measuring floc size in a flush mixer to be used for floc control. A control system using model predictive control was developed on the floc size data. A series of experiments was performed to confirm controllability of settled water quality by controlling flush mixer floc size. An automatic control with feedback from the coagulation process was evaluated as practical and reliable. Finally this new control method was applied for actual plant and evaluated as practical.

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The removal of turbid materials from AMD using bentonite clay, Fe or Al salt, MgCO3 and flocculent with varying agitations

Water Practice & Technology ◽

10.2166/wpt.2020.040 ◽

2020 ◽

Vol 15 (3) ◽

pp. 580-597

Author(s):

I. O. Ntwampe

Keyword(s):

Removal Efficiency ◽

Mine Drainage ◽

Bentonite Clay ◽

Jar Test ◽

Oxidation Reduction ◽

Treated Effluent ◽

Oxidation Reduction Potential ◽

Changing Trend ◽

Series Of Experiments ◽

Slow Mixing

Abstract A series of experiments was conducted using 200 mL of acid mine drainage (AMD) collected from Krugersdorp, South Africa, to determine turbid materials removal efficiency of a combination of bentonite clay, Fe or Al salt and MgCO3. The sample was poured into five 500 mL glass beakers using bentonite clay, FeCl3, AlCl3 and MgCO3 dosage respectively. The samples were treated in jar test at rapid and slow mixing, allowed to settle for 1 hour, then the pH, conductivity, total suspended solids (TSS), dissolved oxygen (DO) and oxidation reduction potential (ORP) were measured (exp A). A second and third similar sets of experiments were conducted with a combination of bentonite clay and MgCO3 (flocculent) dosage (exp B), and FeCl3 with slow mixing only (exp C). Experimental results revealed that the pH of treated effluent with bentonite clay does not exhibit significant increasing trend because of insignificant hydrolysis, whereas the pH of samples with FeCl3, AlCl3 and MgCO3 exhibit a slight decreasing trend, showing a low rate of hydrolysis. The DO and ORP of treated effluent does not show a significant changing trend compared to the untreated AMD sample. Residual TSS of the AMD samples treated with a flocculent is lower than the samples treated with bentonite clay, FeCl, AlCl3 and MgCO3. Residual turbidity of the samples with rapid mixing is identical to that of the corresponding samples with slow mixing. TSS removal efficiency of a flocculent is higher compared to other reagents. The results show that synthetic flocculent is an ideal replacement for inorganic coagulants. The scanning electron microscopy (SEM) micrographs exhibit slides with dense-sponge like flocs showing high adsorption capacity.

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Experimental Analysis of Floc Size Distribution and Hydrodynamics in a Jar-Test

Chemical Engineering Research and Design ◽

10.1205/02638760152721587 ◽

2001 ◽

Vol 79 (8) ◽

pp. 1017-1024 ◽

Cited By ~ 45

Author(s):

D. Bouyer ◽

A. Line ◽

A. Cockx ◽

Z. Do-quang

Keyword(s):

Size Distribution ◽

Experimental Analysis ◽

Floc Size ◽

Jar Test

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Shear-Dependent Yield Stress of Iron Ore Fine Tailings in Two-Step Flocculation Process

Advances in Materials Science and Engineering ◽

10.1155/2020/6611392 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Ying Yang ◽

Hongjiang Wang ◽

Bern Klein ◽

Aixiang Wu

Keyword(s):

Fractal Dimension ◽

Yield Stress ◽

Network Structure ◽

Iron Ore ◽

Shear Resistance ◽

Strength Factor ◽

Floc Size ◽

Fine Tailings ◽

Floc Strength ◽

Flocculation Process

Both shear and flocculation have a significant influence on the rheological behavior of tailings, especially the yield stress. In the two-step flocculation process, the above two kinds of actions exist at the same time, and they influence each other. In order to explore the change rule of the yield stress and its internal causes, a two-step flocculation process of the iron ore fine tailings with different shear conditions in the four different phases was designed. In the primary flocculation phase, tailing particles combined with the primary flocculant and formed a primary floc network structure. In the primary broken phase, shear destroyed the primary floc network structure and decreased the average floc size, so the shear-dependent yield stress, the floc strength factor, and the fractal dimension decreased. In the secondary flocculation phase, broken floc combined with the secondary flocculant and produced a more compact floc network structure which had a better shear resistance. Therefore, in the secondary broken phase, with the increase of shear, the decrease of yield stress, the floc strength factor, and fractal dimension were less obvious than that in the primary broken phase. In both two broken phases, the yield stress of the secondary flocculating slurry was always higher than that of the primary flocculating slurry, but with the increase of shear, the difference became smaller. The floc strength and fractal dimension also showed the same rule. The internal reasons for the stronger shear resistance of the secondary flocculating slurry were the increase of the number of binding sites, the electric neutralization between the two flocculants, and the steric hindrance effect of the flocculants.

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The Optimal Initiation Timing of Surfactant-Polymer Flooding in a Waterflooded Conglomerate Reservoir

SPE Journal ◽

10.2118/205358-pa ◽

2021 ◽

pp. 1-14

Author(s):

Zheyu Liu ◽

Yiqiang Li ◽

Xin Chen ◽

Yukun Chen ◽

Jianrong Lyu ◽

...

Keyword(s):

Oil Recovery ◽

Flow Curve ◽

Online Monitoring ◽

Injection Pressure ◽

Oil Fields ◽

Fractional Flow ◽

Series Of Experiments ◽

Water Cut ◽

The Moment ◽

Swept Volume

Summary Surfactant-polymer (SP) flooding has been regarded as an efficient technique for enhanced oil recovery in the development of mature oil fields, especially for those with heterogeneous conglomerate reservoirs. However, people are still unclear about the optimal SP flooding initiation timing (OSPT) that is expected to contribute to the maximum ultimate recovery factor in the case with a limited amount of SP solution injection. Accordingly, this study aims to investigate OSPT through conducting a series of experiments, including nuclear magnetic resonance (NMR) online monitoring, full-diameter coreflooding, and microfluidic study. The fractional-flow curve is used to identify OSPT, of which the effect on the oil recovery is analyzed. OSPT is demonstrated to be dependent on the amount of injected SP solution. An earlier-started SP flooding is favorable for achieving higher oil recovery factors under the premise of sufficiently high SP solution injection [more than 1.5 pore volume (PV)]. With the commonly used 0.65 PV of SP solution in the reservoir scale, OSPT is suggested to be at the moment when a water cut of 80 to 90% is reached. The formation of dense emulsions in the early-started SP flooding affects the performance of the post-waterflooding, which eventually decreases the ultimate oil recoveries because of inadequacy of SP solution. An earlier-started SP flooding contributes to a larger swept volume, but the initial efficiency of the SP flooding is lower than that of the waterflooding when the injection pressure is constant. OSPT is proposed through analyzing the fractional-flow curve in the case of 0.65 PV of SP injection, and the determined OSPT is validated by coreflooding experiments and field data. Moreover, OSPT for the conglomerate reservoir is suggested to be earlier than that for the relatively homogenous sandstone reservoir.

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Formation and breakage of flocs using dual polymers

Water Science & Technology ◽

10.2166/wst.2006.226 ◽

2006 ◽

Vol 53 (7) ◽

pp. 217-223 ◽

Cited By ~ 8

Author(s):

M.A. Yukselen ◽

J. Gregory ◽

E. Soyer

Keyword(s):

Shear Rate ◽

Test Procedure ◽

Optical Monitoring ◽

Ionic Polymers ◽

Ionic Polymer ◽

Polymer Addition ◽

Anionic Polymers ◽

Jar Test ◽

Average Shear ◽

Floc Strength

The effect of shear on the formation and break-up of flocs generated using cationic, anionic and non-ionic polymers, and dual combinations of these, has been investigated using conventional jar test procedure and by continuous optical monitoring. The breakage of flocs was followed at a high stirring speed, corresponding to average shear rate (G) of approximately 520 s−1. Most of the breakage occurred within a few seconds of increasing the shear rate. After each breakage, the stirring rate was reduced to the original value of 50 rpm (G≈23 s−1) to allow the flocs to regrow. For cationic–anionic polymers case, the regrowth of flocs was fully reversible and the breakage factors were smallest indicating highest floc strength. In contrast, flocs formed using non-ionic polymer together with anionic or cationic did not produce as strong flocs. It is found that the sequence of polymer addition is not very significant for floc formation and reformation when the cationic–anionic dual system is used.

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Competence of blended coagulants for surface water treatment

Applied Water Science ◽

10.1007/s13201-019-1108-4 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 1

Author(s):

Vara Saritha ◽

Manoj Kumar Karnena ◽

Bhavya Kavitha Dwarapureddi

Keyword(s):

Surface Water ◽

Physicochemical Parameters ◽

Test Apparatus ◽

Turbidity Removal ◽

Floc Size ◽

Surface Water Treatment ◽

Jar Test ◽

Coagulation And Flocculation ◽

Natural Coagulants ◽

Surface Water Samples

AbstractOwing to the advantages of the natural coagulants under study, the present objective is to study the efficiency of blended coagulants: alum and chitin; alum and sago; and alum + chitin + sago. In this attempt, we have reduced the quantity of alum dose and added increasing quantities of the natural coagulants. The surface water samples collected from nearby sources were analyzed for the following parameters pre- and post-treatment with the coagulants. Coagulation and flocculation experiments were carried out using conventional jar test apparatus. Turbidity removal was observed to be nearly 99.29% at all pH ranges and doses. Removal of conductivity, solids and hardness was 58.83%, 32.03% and 33.33%, respectively. From the results obtained, it can be observed that the efficiency of blended coagulants in removal of various physicochemical parameters from the waters was better when compared to individual coagulants. The floc size in blend coagulants was larger than that of single coagulants. The data obtained in this study indicated the coagulation efficiency could be enhanced by using the blend coagulant.

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Eco-friendly approach for elimination of olive mill wastewaters (OMW) toxicity using cactus prickly pears juice as a coagulant

Water Practice & Technology ◽

10.2166/wpt.2020.076 ◽

2020 ◽

Vol 15 (4) ◽

pp. 1050-1067

Author(s):

M. Neffa ◽

M. Taourirte ◽

N. Ouazzani ◽

H. Hanine

Keyword(s):

Low Cost ◽

Mixing Time ◽

Oxygen Demand ◽

Physicochemical Analysis ◽

Jar Test ◽

Coagulation Mechanism ◽

Olive Mill Wastewaters ◽

Series Of Experiments ◽

Prickly Pears ◽

Olive Mill

Abstract Currently, research focuses on the application of newer biocoagulant products in wastewater treatment. In this study, the performance of cactus juice to clarify Olive Mill Wastewater (OMW) was investigated by using Jar-test experimentation and assessed by physicochemical analysis of the obtained supernatant: turbidity, total suspended solids (TSS), (λ465; λ395) absorbance, polyphenols (pp), chemical oxygen demand (COD) and Fourier-Transform-Infrared spectroscopy (FTIR) on lyophilized sludge. A series of experiments were conducted to estimate the influence of various experimental parameters, such as the amounts of biocoagulants used, time, stirring speed, and pH. The study showed the optimal coagulation conditions were as follows: sample pH10; cactus juice dose, 10% (v/v); rapid mixing time, 30 s at a speed of 150 rp/min. Under these conditions, the overall removals of 74% for COD, 93% for turbidity and 51% for polyphenols were achieved. As referring to the FTIR analysis, the cactus juice of Opuntia spp. operates predominantly through an adsorption interparticle bridging coagulation mechanism. These results are encouraging in the context of developing a low-cost technology and eco-friendly approach for the effective management of OMW.

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Understanding the coagulation mechanism and floc properties induced by Fe(VI) and FeCl3: population balance modeling

Water Science & Technology ◽

10.2166/wst.2021.150 ◽

2021 ◽

Author(s):

Xinliang Liu ◽

Hailiang Yin ◽

Jian Zhao ◽

Ziqi Guo ◽

Zhen Liu ◽

...

Keyword(s):

Practical Importance ◽

Population Balance ◽

Collision Efficiency ◽

Population Balance Modeling ◽

Floc Size ◽

Coagulation Mechanism ◽

Coagulation Kinetics ◽

Floc Strength ◽

Floc Properties ◽

Positive Effect

Abstract Coagulation kinetics and floc properties are of great fundamental and practical importance in the field of water treatment. To investigate the performance of Fe(VI) and Fe(III) salt on particle coagulation, Malvern Mastersizer 2000 was employed to continuously and simultaneously monitor the kaolin floc size and structure change, and population balance modeling was used to investigate the coagulation mechanism. The results show dosage increase had positive effect on collision efficiency and floc strength and negative effect on restructure rate. Low shear rate resulted in higher collision efficiency and stronger floc. Low water temperature had a pronounced detrimental effect on coagulation kinetics. Temperature increase showed the most significant positive effect on collision efficiency, floc strength and restructure rate. The optimum pH zone for the coagulation was found to be between 6 and 8. Further pH increase lowered the collision efficiency and floc strength and increased the restructure rate. FeCl3 resulted in a larger ratio of the mass to volume of kaolin flocs (compactness) than those induced by ferrate.

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