Slow-speed, low-shear paddle wheel flocculators for controlled floc growth. Horizontal or vertical shaft configurations, VSD-driven, G-value 10–60 s−¹. Ideal for sensitive flocs ahead of DAF, lamella, or gravity settling.
The paddle flocculator is the most widely used mechanical flocculator type in both drinking water and industrial wastewater treatment. Long horizontal or vertical shafts carry flat or profiled paddle blades at radii sized to produce the target Camp & Stein G-value at low rotational speeds (typically 1–6 rpm). This gentle regime minimises shear stress on growing floc aggregates, permitting the formation of large, dense, rapidly-settling particles.
G-value for paddle flocculators: G = √(CD·A·vrel³·ρ / 2μV) where CD = drag coefficient (≈1.5 for flat blades), A = total blade area (m²), vrel = blade velocity relative to fluid (m/s), ρ = fluid density, μ = dynamic viscosity, V = tank volume. Blade tip speed is kept to 0.1–0.6 m/s to maintain G within the 10–60 s−¹ target window.
Variable-speed drives adjust paddle rpm in real time, tracking changes in flow rate, raw water temperature (viscosity), and coagulant dose without manual intervention.
Two or three chambers in series with descending G-value (e.g., 50 → 30 → 15 s−¹) promote collision in the first chamber and consolidation in the last, producing a robust floc with low SVI.
Horizontal-shaft paddle wheels suit wide, shallow rectangular tanks common in conventional WTPs. Vertical-shaft designs fit circular or square compact tanks, simplifying drive access in constrained plant rooms.
External gear-motor and bearing assembly above the waterline for easy inspection and grease replenishment. Submerged bearing options in self-lubricating polymer bush where drive access is limited.
| Application | Target G (s−¹) | Stages | Typical HRT | Downstream Separation |
|---|---|---|---|---|
| Drinking water (surface) | 20–50 | 2–3 | 20–30 min | Gravity sedimentation or DAF |
| DAF pre-flocculation | 15–40 | 1–2 | 10–20 min | Dissolved air flotation |
| Lamella pre-treatment | 20–50 | 2 | 15–25 min | Inclined plate settler |
| Phosphorus precipitation | 30–60 | 1–2 | 15–20 min | Lamella or gravity sedimentation |
| Industrial WWTP (food) | 20–50 | 2 | 15–20 min | DAF or circular clarifier |
Where the coagulant regime produces low-density or gelatinous aggregates (e.g., high-DOC surface waters with alum), the low-shear paddle environment avoids breakup that turbine impellers may cause.
Long horizontal shafts spanning rectangular concrete or GRP tanks are efficient at flows above 1,000 m³/day, leveraging existing civil basin geometry without tank modification.
Paddle-wheel flocculation is the most common design in conventional WTPs, making it the low-risk choice for utility projects where proven, auditable design standards are required.
In high-TSS industrial streams (>500 mg/L), turbine flocculators or hydraulic baffled designs may outperform paddle wheels due to better radial mixing across the full tank depth.
Slow-speed horizontal or vertical paddle wheels for gentle, sustained floc growth.
View PageAxial and radial turbine impellers for higher-intensity or multi-stage flocculation.
View PageChemical coagulant flash-mixing without moving parts using pipe-mounted static elements.
View PageCamp & Stein G-value calculations, GT product, tapered flocculation staging, and chamber sizing.
View PageDiagnose pin floc, carry-over, excessive breakup, and drive mechanical faults.
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Contact UsOur 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.
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