Activated Sludge System
In an Activated Sludge System, wastewater is introduced into an aeration tank where it is vigorously mixed with a community of aerobic microorganisms. These microorganisms consume dissolved organic pollutants as their food source. As they metabolize the organic load, they grow, multiply, and form flocculent biomass, commonly known as activated sludge.
This mixture of treated wastewater and microbial flocs then flows to a secondary clarifier, where:
- The biomass settles under gravity
- Clarified treated water moves forward for tertiary treatment
- Settled sludge becomes either Return Activated Sludge (RAS) or Waste Activated Sludge (WAS)
Return Activated Sludge (RAS)
A portion of the settled biomass is pumped back to the aeration tank to maintain the required concentration of microorganisms. This recycled sludge is known as Return Activated Sludge.
RAS is crucial because it:
- Keeps the microbial community active and balanced
- Ensures stable BOD reduction
- Maintains the appropriate Mixed Liquor Suspended Solids (MLSS) levels
- Prevents system upset during variable influent loads
Waste Activated Sludge (WAS)
As microorganisms multiply, excess biomass accumulates in the system. If left unmanaged, this leads to:
- Poor settling characteristics
- Reduced oxygen transfer efficiency
- System overload and rising MLSS
To maintain process stability, a portion of the sludge is intentionally removed as Waste Activated Sludge (WAS).
WAS is then transferred to further treatment processes such as:
- Sludge thickening
- Anaerobic digestion
- Dewatering
- Final disposal
Hydro Prokav Pumps for RAS & WAS Transfer
Hydro Prokav Progressive Cavity Pumps ensure smooth, non‑pulsating, low‑shear transfer of RAS, preventing floc breakage and preserving sludge settleability. Their ability to handle high solids efficiently makes them ideal for continuous RAS recirculation.
Waste Activated Sludge is thicker, more viscous, and contains higher solids than RAS — conditions where Hydro Prokav Progressive Cavity Pumps excel. Their robust design allows reliable, clog‑free pumping of Waste Activated Sludge with precise flow control, making them ideal for:
- Intermittent or continuous sludge waste
- Feeding thickeners, filter presses, or digesters
- Long‑distance and high‑solids pumping
Why Hydro Prokav Pumps Are Ideal for Secondary Treatment
Hydro Prokav Progressive Cavity Pumps deliver several advantages across secondary treatment operations:
- Low shear movement protects sludge floc integrity
- Consistent, metered flow ideal for biological process stability
- Capability to handle varying viscosities and solids
- Long rotor–stator life due to optimized design
- Minimal pulsation, ensuring smooth sludge transfer and reduced pipeline stress
- High reliability in demanding wastewater applications
Whether it’s RAS recirculation or WAS extraction, Hydro Prokav pumps provide efficient, reliable, and process‑friendly solutions that support uninterrupted secondary treatment performance.