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Flocculators

Mechanical and hydraulic flocculation equipment engineered for controlled particle aggregation in drinking water, industrial process, and wastewater treatment. Paddle, turbine, and static-mixer types — VSD-controlled G-value from 10 to 100 s−&sup1.

What Is Flocculation — and Why Does the G-Value Matter?

Flocculation is the third stage of the coagulation–flocculation–separation train. After coagulant addition and rapid flash-mixing (G > 300 s−¹), destabilised micro-particles must be grown into settleable or flotable macro-flocs through slow, controlled agitation. The governing parameter is the root-mean-square velocity gradient G (Camp & Stein, 1943):

G = √(P / μV)    where P = power input (W), μ = dynamic viscosity (Pa·s), V = tank volume (m³).
Typical flocculation target: G = 20–80 s−&sup1. The cumulative GT product (G × hydraulic retention time) should fall between 10,000 and 150,000 for most coagulation applications.

Too high a G-value shears growing floc aggregates back into primary particles. Too low a value gives insufficient collision frequency, leaving the water turbid after the separation stage. Our flocculators are sized and controlled to maintain the target G across the full diurnal flow range.

Variable-Speed Drive Control

All mechanical flocculators are supplied with a VSD-linked paddle or impeller speed controller, allowing real-time G-value adjustment as flow rate or raw water quality changes.

Tapered Flocculation

Multi-chamber designs apply a descending G-value sequence — high G in the first chamber to promote particle collision, reducing to low G in the final chamber to consolidate and densify the floc prior to separation.

Plug-Flow Hydraulics

Baffled tanks and correct aspect ratios minimise short-circuiting, ensuring that all water receives the full design GT. CFD validation available for critical applications.

Drive Reliability

Gear-motor drives on all paddle and turbine units, with submerged or overhung bearing configurations. IP65 motor standard; ATEX options available for solvent-bearing streams.

Wide Flow Range

Single units from 10 to 10,000 m³/day; parallel trains to 50,000 m³/day. Modular steel or GRP tank construction integrates with new build or retrofit civil basins.

Materials for Aggressive Streams

Wetted parts in SS304, SS316L, or HDPE. Paddle blades profiled in UHMWPE for abrasion resistance in high-solids duties such as mining and aggregate process water.

Flocculator Types at a Glance

TypeG-Value Range (s−¹)Best ApplicationMoving PartsFootprintCapital Cost
Paddle Wheel10–60Municipal WTP, sensitive flocs, DAF pre-treatmentYes — paddle shaftModerateLow–medium
Vertical Turbine20–100Industrial, compact installations, high-solids dutiesYes — impeller shaftSmallMedium
Helical Impeller15–70Lamella pre-treatment, delicate flocs, low-shear dutyYes — helical shaftSmallMedium
Static / Inline Mixer50–300 (flash mix)Coagulant dispersion, small flows, pipe-mounted dutyNoneMinimalVery low
Hydraulic Baffled20–60Developing-world WTPs, low-maintenance sitesNoneLargeLow (civil)

Technical Specifications

Flow Range
10–50,000 m³/day
G-Value (mechanical)
10–100 s−¹
GT Product
10,000–150,000
Retention Time
10–30 min
Power Input
0.37–15 kW
Tank Volume
1–500 m³
Materials
SS304 / SS316L / GRP
Drive Standard
Gear-motor + VSD
Design note: Final G-value and chamber count require a jar-test programme. Contact our engineers for a no-obligation feasibility review, or visit our design guide for worked examples.

Where Flocculators Are Used

Drinking Water Treatment

Surface water coagulation–flocculation–sedimentation for turbidity and NOM removal. G-value profiling to meet tight filter influent targets.

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Industrial Wastewater

Physico-chemical pre-treatment for food, beverage, chemical, and mining effluents prior to DAF, lamella, or clarifier separation.

View Treatment Process

DAF Pre-Treatment

Optimising floc structure for dissolved air flotation — target G = 20–40 s−¹ to produce neutrally buoyant aggregates that adhere readily to micro-bubbles.

View DAF Systems

Lamella Clarifier Pre-Treatment

Conditioning particles to 50–200 μm settleable flocs ahead of inclined-plate settlers. Prevents carry-over and reduces polymer consumption.

View Lamella Clarifiers

Phosphorus Removal

Chemical precipitation with iron or aluminium salts followed by flocculation for effluent TP < 0.1 mg/L to meet Environment Agency discharge consents.

View Coagulation Process

Heavy Metal Precipitation

Controlled pH adjustment and flocculation for chromium, nickel, copper, and zinc removal from electroplating and surface treatment effluents.

View Chemical Dosing

Desalination Pre-Treatment

Seawater coagulation–flocculation to remove colloidal particles and SDI prior to UF or direct-to-RO pre-treatment trains.

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Pulp & Paper

White-water recovery and effluent treatment using fibre-specific flocculant programmes with tapered G-value to preserve long-fibre flocs.

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Coagulation–Flocculation–Separation Train

Flocculators sit between the rapid-mix (coagulation) stage and the separation unit. Correct sequencing and G-value profiling across the train are critical to downstream performance.

1. Rapid Mixing (G > 300 s−¹)

Coagulant dispersed in < 30 seconds. Chemical dosing systems inject alum, PAC, or ferric at the flash-mix point immediately upstream of the rapid-mix tank or static mixer.

2. Flocculation (G = 20–80 s−¹)

One to three chambers with tapered G-value grow particles to 50–500 μm. Flocculant polymer is dosed at the inlet of the first or second chamber to bridge and bind primary aggregates.

3. Separation

Flocculated water flows to DAF, lamella clarifier, or gravity sedimentation. Correct floc size and density is critical to separation efficiency and sludge volume index.

Integrated design: Reynolds & Bauhm designs the complete coagulation–flocculation–separation train as a single hydraulic system. G-value profiles, residence times, and chemical dosing points are optimised together — not as isolated equipment selections. Speak to our engineers for a process review.

Explore the Full Flocculator Cluster

Paddle Flocculators

Slow-speed horizontal or vertical paddle wheels for gentle, sustained floc growth.

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Turbine Flocculators

Axial and radial turbine impellers for higher-intensity or multi-stage flocculation.

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Static / Inline Mixers

Chemical coagulant flash-mixing without moving parts using pipe-mounted static elements.

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Design Guide (G-Value)

Camp & Stein G-value calculations, GT product, tapered flocculation staging, and chamber sizing.

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Troubleshooting Guide

Diagnose pin floc, carry-over, excessive breakup, and drive mechanical faults.

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Speak to Our Engineers

Discuss your specific requirements with our technical team and receive a tailored proposal for your project.

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Specify Your Flocculator

Our process engineers will review your raw water quality, coagulant regime, and downstream separation method to recommend the optimum flocculator type, G-value profile, and chamber configuration.

Industries We Serve