coagulation flocculation mixing times

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COAGULATION AND FLOCCULATION

More coagulant chemicals may need to be added. A high-energy, rapid-mix to properly disperse coagulant and promote particle collisions is needed to achieve good coagulation. Over-mixing does not affect coagulation, but insufficient mixing will leave this step incomplete. Contact time in the rapid-mix chamber is typically...

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The effect of fast mixing conditions on the coagulation–flocculation ...

Jul 10, 2014 ... Fast mixing time had a clear effect on the flocs resistance to applied shear during the slow mixing phase. For all fast mixing times, 120 rpm caused the formation of largest flocs. Stronger flocs, indicated by the least change in flocculation index with time, required 60 s to form at all fast mixing speeds. Turbidity...

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The effect of fast mixing conditions on the coagulation–flocculation ...

Jul 10, 2014 ... The effect of fast mixing on floc formation and pollutant removal, using magnesium hydroxide as a coagulant, was investigated through characterization of relative strength and size of the formed flocs while operating at different mixing speeds and mixing times using a dynamic optical monitoring apparatus,...

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Rapid Mixing, Coagulation - Flocculation - nptel

Flocculation or gentle agitation results from velocity differences or gradients in the coagulated water, which causes the fine moving, destabilized particles to come into contact and become large, readily settleable flocs. It is a common practice to provide an initial rapid (or) flash mix for the dispersal of the coagulant or other...

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The Effect of Fast Mixing Conditions on the Coagulation-Flocculation ...

least change in flocculation index (FI) with time, required 60 seconds to form at all fast mixing speeds. Turbidity and TSS removal efficiencies depended not only on fast mixing speed but also on fast mixing time such that higher fast mixing speeds were required for shorter mixing times. Keywords coagulation, flocculation...

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Evaluation of chemical coagulation–flocculation aids for the removal ...

... industry, i.e. alum and ferric chloride. In addition to determining their effectiveness in removing both suspended solids and phosphorus, a systematic evaluation of the variables encountered in the coagulation–flocculation process (mixing and flocculation stirring speeds and durations, and settling times) was conducted.

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Optimizing Flocculation in Water Treatment | Dynamix Agitators

Apr 7, 2016 ... In our previous article, Agitator Design for Wastewater Clarification Part 1, we looked at how to optimize a mixer for the unit process of coagulation. ... of mixing. However, in flocculation, the amount of time the polymer and coagulated waste particles are close or in contact greatly influences the floc formation.

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Optimization of coagulation-flocculation parameters using a ...

Jul 23, 2014 ... flocculation parameters while monitoring floc size and structure as well as the rate of floc formation during co- agulation using alum. The optimal coagulation conditions were as follows: sample pH 8; alum dosage, 3 mg L−1 as Al3+; G value, 172 s−1; rapid mixing time, 20 s. These conditions resulted in...

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Coagulation and Flocculation in Water and Wastewater Treatment ...

Coagulation and flocculation are essential processes in various disciplines. In potable water treatment, clarification of water using coagulating agents has been practiced from ancient times. As early as 2000 BC the Egyptians used almonds smeared around vessels to clarify river water. The use of alum as a coagulant by the...

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Coagulation, flocculation and clarification processes are used when ...

Rapid mixing of coagulant. Flocculation should be achieved by gentle mixing so as to maximize the number of collisions between suspended particles and flocs, without breaking the flocs up through rapid mixing. Flow rates in hydraulic flocculators should be in the range 0.1 to 0.3 metres per second, with a retention time of...

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Tank Mixing System - Evoqua Water Technologies

A floc tank is a tank with mixer system used for gentle mixing of flocculent (i.e., polymer) to facilitate flocculation of coagulated particles prior to flotation, ​A floc tube is a length of ... The longer retention time also buffers changes in wastewater characteristics (i.e., pH, contaminant concentrations, etc.) ​Has lower retention...

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Influence of the Mixing Energy Consumption Affecting Coagulation ...

Feb 16, 2017 ... the slow mixing stage in flocculation and, to some extent, their settling characteristics. .... added at the start of the rapid mix process. Coagulation was conducted for 90 s at a specific G-value. Flocculation was achieved at a fixed G-value of 46 s. −1 ... plants,8,16 except for the G-value and 90 s of mixing time.

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the role of rapid mixing time on a flocculation process

the rapid mixing time are deduced. KEYWORDS. Coagulation kinetics7 flocculation kinetics7 mixing7 hydroxide floc characteristics7 floc structure. INTRODUCTION. A coagulation-flocculation process consists of three steps: coagula tion of the suspended solids, flocculation of the destabilized particles and elimination of the...

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water treatment manuals coagulation, flocculation & clarification

Figure 6: Variation of pH With Time in a Raw Water Reservoir Containing Algae. 23. Figure 7: Methods of Flash Mixing. 25. Figure 8: Horizontal Flocculator and Horizontal Flow Sedimentation Tank. 27. Figure 9: Hopper Bottomed Upflow Sludge Blanket Settlement Tank. 28. Figure 10: Flat-Bottomed Upflow Sludge Blanket...

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12VAC5-590-870. Mixing and Sedimentation. - Xinhaiia Law

D. Flocculation mixing is the agitation of treated water at low velocity gradients for sufficient time to agglomerate coagulated particles. 1. Basin inlet and outlet design shall prevent short circuiting and destruction of floc. A drain and overflow shall be provided. Multiple units shall be provided for continuous operability and each...

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Time requirement for rapid-mixing in coagulation

various rapid-mixing times indicated that mixing time had significant impact on charge neutralization and sweep coagulation. The difference in .... parameter for rapid-mixing, the duration required for coagulation. PDA was first introduced by. Gregory to monitor the state of aggregation of flocculation [15]. Our laboratory has...

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Coagulation and flocculation - TU Delft OpenCourseWare

After rapid mixing, a slow stirring, and a settling phase, the water turbidity is measured. By modifying the process conditions (dosage, pH, flocculation time, settling time, stirring energy for mixing and/or flocculation), the optimal conditions can be determined. Mechanisms. The coagulation mechanisms discussed above.

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CHEMICAL CLARIFICATION – COAGULATION METHODS

Increase Particle Size. (Average Diameter). CHEMICAL. CLARIFICATION. Particle Size versus Settling Time. Particle Size. mm. Order of Size. Time to Settle. 1.0 ... Coagulation. Rapid Mixing; “Pin-point” Floc Formation. Chemical Addition. Flocculation. Slow Mixing; Floc Growth; Increased Diameter. Solids Separation.

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EFFECT OF MIXING CONDITIONS ON FLOCCULATION KINETICS ...

It was observed that flocculation time was very fast, occurring within the period of polymer addition. Long term shearing did not result in floc breakage and the ... The coagulation radius of the particles was assumed to be very small in comparison with the microscale of turbulence, l t. It was also assumed that there is complete...

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THE EFFECT OF HYDRAULIC JUMP COAGULATION MIXER ON ...

Hydraulic jump mixing aims to instantly and efficiently disperse coagulant species into raw water, before flocculation processes. Mechanical mixing with a longer retention time cannot guarantee an instantaneous and uniform coagulant dispersion. To overcome this problem, the hydraulic jump can be used for chemicals...

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Insights into the role of mixing conditions in coagulation–flocculation ...

Insights into the role of mixing conditions in coagulation–flocculation process: evaluation from performance ... Appropriate mixing conditions are always favorable during enhanced coagulation for the desirable performance. ... slightly prolonged rapid mixing time (120 s) improved floc density with better settleability when the.

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Homework #6. Coagulation, Flocculation, Sedimentation

Fall 2009. Homework #6. Coagulation, Flocculation, Sedimentation. 1. The design flow for a water treatment plant (WTP) is 1 MGD (3.8x10. 3 m. 3. /d). The rapid mixing tank will have a mechanical mixer and the average alum dosage will be 30 mg/L. The theoretical mean hydraulic detention time of the tank will be 1 minute.

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Effects of Coagulation pH and Mixing Conditions on Characteristics ...

conditions such as rapid mixing time, slow stirring speed and breakage period ... It was found that flocculation index was very significantly related to the ..... Flocculation Index. Time (s). Fig. 5. Floc formation, breakage and re-growth for different rapid mixing times. coagulation condition: pH=6 and 2.5mg/L Al as coagulant...

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flocculation coagulation - Technical Learning College

Jan 1, 2018 ... impacting coagulation. During flocculation, gentle mixing accelerates the rate of particle collision, and the destabilized particles are further aggregated and enmeshed into larger precipitates. Flocculation is affected by several parameters, including the mixing speed, mixing intensity (G), and mixing time. The.

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Design of Rapid mixing (Coagulation) CHAPTER: 9 Rapid mixing ...

Rapid mixing unit : provide complete mixing of the coagulant and raw water. Destabilization of colloidal particle ... G for rapid mix → 700-1000 sec-1 t (detention time) for rapid mixing → 20-60 sec. 2 ... from coagulation may still settle very slowly. Flocculation is a slow mixing process in which these particles are bought.

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Effect of Mixing Speed and Time on Dyes Removal ... - ISSR Journals

Sep 3, 2014 ... At maximum dyes removal is achieved when the mixing time is 18 min it is 85.6% and 72.5% for. Polymer A110 and Polymer 202As respectively. KEYWORDS: Dye bath effluent, Coagulation, flocculation, mixing speed, mixing time, color removal. INTRODUCTION. Textile industry is the greatest source of...

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Treatment Processes * Conventional Coagulation/Flocculation ...

Review treatment plant hydraulics to provide improved mixing of chemicals. P5.1.1.8. Insufficient contact time for floc formation. Check mixing times are adequate for effective coagulation and flocculation over the range of flow rates through the plant, and that carry over to the filter is not excessive. (See P5.1.1.7.)...

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Flocculation kinetics using dual coagulants: effects of temperature ...

flocculation. Although the G values used for rapid mixing in the above work are rather low, the G value of 200 s"' could still give a good insight on the effects of rapid mixing time, and their conclusions would still be valid. Letterman et al. (1973) used alum in a conventional jar test procedure to coagulate a powdered activated...

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Effect of various mixing devices and patterns on flocculation kinetics ...

Sajjad, Md. Wahid, "Effect of various mixing devices and patterns on flocculation kinetics in water treatment " (1995). Retrospective. Theses and ..... Typical pH versus time curves during coagulation-flocculation process for two ... the effect of rapid mixing intensity on flocculation kinetics with metal salts as the coagulant.

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mixing and coagulation - MOST Water Training

Oct 26, 2015 ... The purpose of coagulation and flocculation — and ACTIFLOW, for that matter — is to convert colloidal particles into larger, suspended particles. And these larger ... And like all of our courses at MOST, this is a one-hour, online video that you can purchase at any time for only $10. And you can play it as...

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Conventional Clarification | GE Water

The coagulation/flocculation and sedimentation process requires three distinct unit processes: high shear, rapid mix for coagulation; low shear, high retention time, moderate mixing for flocculation; liquid and solids separation. Horizontal Flow Clarifiers. Originally, conventional clarification units consisted of large, rectangular...

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Operating conditions of coagulation-flocculation process for high ...

May 2, 2017 ... Worth mentioning, the efficiency of the coagulation and flocculation process, which affects the overall efficiency of the treatment process, depends on various factors. These include the quantity (dosage) and type of coagulant and flocculant used, retention time, the speed of the mixer and the temperature at...

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Coagulation/Flocculation In Processing Plants With Limited Space

For use in Coagulation/Flocculation applications where suspended solids and particles must be removed from wastewater and space is limited. A coagulant, added to wastewater downstream of Westfall's Static Mixer Model 2800, undergoes high shear turbulence. Rapid mixing is generated to disperse the coagulant...

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coagulation, flocculation and clarification of drinking water - Hach

Jan 1, 2014 ... The intent of this paper is to provide cursory information about coagulation, flocculation and clarification. This knowledge will provide a basis for understanding the needs of the customer wishing to monitor these processes. There is no attempt to provide an exhaustive description of various coagulants,...

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L 17 coagulation and flocculation - SlideShare

Oct 16, 2013 ... JAR TEST A jar test simulates the coagulation and flocculation processes in batch mode; 24. 30 Fill the jars with raw water sample (500 or 1000 mL) – usually 6 jars This time adjust pH of all jars at optimum (@ 7) while mixing using H2SO4 or NaOH/lime Add different doses of the selected coagulant...

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Lecture 5. Coagulation and Flocculation

Rapid Mix Design Considerations. Most chemical reactions in coagulation occur in less than 0.1 seconds. It is therefore important that mixing be as instantaneous and complete as possible. Since G is a measure of the mixing intensity, selection of G and Gt where t is the detention time of the fluid in the rapid mixer, are...

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Impact of Coagulation Mixing and Time on CST Values - IAENG

mixing time. By excluding the initial value, the impact of rapid mixing velocity and rapid mixing time are similar, where the gradual increase in rapid mixing ... The coagulation process consists of two-stage mixing processes: rapid mixing (coagulation) and slow mixing. (flocculation). Rapid mixing is employed at the first stage...

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Water Treatment Process Troubleshooting Guide for Class A and ...

2. Water has a milky appearance with a bluish tint. 3. Floc size increases in the flocculation basin then starts to break up. 4. Floc rapidly settles in the first part of the sedimentation basin. Corrective Actions a. Mixing intensity of the downstream flocculator is too high b. Excessive Coagulant dosage c. Excessive alum dosage d.

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Polymers for Water Clarification - treating water and wastewater

Polymers for Water Clarification - treating water and wastewater | nonionic, anionic, organic, flocculants, coagulants, Technical Support Available. ... The use of the inorganic coagulant speeds the total destabilization time to accommodate the short mixing times encountered. The use of the organic polymer reduces treatment...

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An Overview of Coagulation-Flocculation Technology - WCP Online

Apr 17, 2014 ... Mixing time is generally less than one minute (referred to. as flash mixing) to minimize breakdown of the floc into small. suspended particles. After mixing, coagulation occurs due to. charge neutralization, which allows fine particles to coalesce into. larger particles (micro-floc). Flocculation involves the...

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