How grid flocculation works, the cell forms we produce, material selection, general design guidance and what to send us for a quotation.
← Back to Flocculation GridFlocculation is the first key step of the three conventional physical treatment processes in a water plant, and the result of that reaction directly affects both the quality and the quantity of the water produced. Raw water carrying suspended solids, colloids and dissolved matter is dosed with a coagulant (or coagulant aid). In the reaction zone the liquid and the solid phase move almost in step, and because the flow channels keep changing as the water passes through the reaction device, the solid and liquid phase particles do not simply move with the bulk flow — they also pulsate up, down and sideways.
The flocculation grid is what defines those channels. A grid panel fills the cross section of the basin with a large number of small cells, so the turbulence is spread across the whole section instead of concentrating in one open flow path. The higher proportion of turbulent micro-vortices raises the number of particle collisions, which is what lets micro-flocs form and grow into flocs large enough to settle in the next stage of the plant.
The grid is a fixed, passive element: no moving parts, no power supply, and the panels can be lifted out when the basin is drained for cleaning.
Four cell forms are available. The form, cell size, panel size and plate thickness are produced to order, because the useful arrangement depends on the basin geometry and on the flow rate the designer has set for each stage.
| Form | Outline |
|---|---|
| Box type | Square or rectangular box-shaped cells formed by intersecting partitions, giving a deep egg-crate panel. The most general-purpose form for a straight flocculation basin. |
| Mesh type | Cell walls formed as an open mesh, so water can pass through the walls as well as along the channels. Suited to basins where a lower resistance to flow is wanted. |
| Hopper type | Cells that narrow towards the bottom like a hopper, so the channel contracts as the flow leaves each cell. |
| Herringbone type | Chevron (angled) cell walls laid out in a herringbone pattern instead of a square grid, which turns the flow sideways as it passes through the panel. |
Outline descriptions are given for orientation only. Cell geometry, panel size and layer arrangement are confirmed against your basin drawing before production.
The grid is produced in four materials, and the choice depends on the water chemistry, the mechanical load on the panel and the temperature of the duty:
Panels in PP, PVC and ABS are supplied in their natural white or ivory colour; stainless steel panels are supplied bare. All four materials can be combined with any of the cell forms above.
A grid flocculation basin is normally designed in stages, with the turbulence intensity falling from the first stage to the last: strong mixing at the inlet to bring particles into contact, gentle mixing at the outlet so that the flocs already formed are not broken up. The number of grid layers, the spacing between layers and the velocity through the grid therefore decrease along the flow path.
Published design guidance for grid and strip flocculation basins generally gives a flocculation time of 12–20 min. This figure is guidance for the basin design, not a property of the grid, and the final values are set by the project designer from the raw water quality and the basin geometry.
We supply the grid packing. Hydraulic design of the basin — stage velocities, layer spacing and head loss — remains with the project designer; we can review the arrangement against the drawing you send us.
All product-specific values are made to order and confirmed at quotation stage. To quote, we need:
| Item | Value |
|---|---|
| Panel size | On request — produced to the basin dimensions |
| Cell size | On request |
| Plate thickness | On request |
| Layer arrangement | On request — confirmed with the project designer |
| Service life | On request — depends on material grade and water quality |
| MOQ | On request |
| Price | On request |
| Lead time | On request — confirmed with the order |
Compiled from Nuoweisen product data (materials, cell forms, features and applications) and from general published guidance on grid flocculation basin design. No product-specific numeric specification is published for this item; panel size, cell size, thickness and service life are made to order and quoted on request.