G R F Dynamic Engineering

we are dealing with (capacity range from 500l 10kl) A settling tank, also known as a sedimentation tank is an component of water or wastewater treatment systems designed to remove suspended solids from liquids through the process of gravity settling. Here's a brief description:
Settling Tank Description
A settling tank is a large basin or chamber where water or wastewater is held for a period of time, allowing heavier particles (such as sand, silt, or organic matter) to settle at the bottom due to gravity. The clarified liquid then flows out from the top, while the collected sludge at the bottom is periodically removed.
Settling tanks are commonly used in:
Water treatment plants (to remove turbidity)
Wastewater treatment (as primary or secondary clarifiers)
Industrial processes (to separate solid-liquid mixtures)

There are two main types:
Rectangular tanks: Water flows horizontally.
Circular tanks: Water flows radially from the center to the edges.
Key design factors include detention time, surface area, inlet/outlet design, and sludge removal mechanisms.
Settling Tank Specifications
1. Type
Rectangular or circular
Primary (removes settleable solids and organic matter) or secondary (after biological treatment to remove biological floc)

2. Dimensions (typical range)
Length (rectangular): 15–30 m
Width (rectangular): 3–12 m
Depth: 2.5–5 m (common: 3.5 m)
Diameter (circular): 5–50 m

3. Flow Rate
Depends on design; often 0.5 – 2.0 m³/m²·hr (surface overflow rate)

4. Detention Time
Water treatment: 2 – 6 hours
Wastewater treatment (primary): 1.5 – 2.5 hours
Secondary clarifier: 2 – 3 hours

5. Surface Overflow Rate (SOR)
Primary tanks: 30 – 50 m³/m²/day
Secondary tanks: 15 – 25 m³/m²/day

6. Sludge Zone
Conical or sloped bottom to facilitate sludge collection
Sludge removal mechanism: scraper arms or pump system

7. Inlet/Outlet
Inlet: Baffles to reduce turbulence
Outlet: Weirs for uniform flow distribution

8. Construction Materials
Reinforced concrete (most common), steel, or HDPE (for temporary/mobile units)

9. Accessories
Scum removal system
Sludge pumps or mechanical scrapers
Access walkways and handrails
Flow measuring devices