Why Poor Mixing Undermines Wastewater Treatment Performance

In wastewater treatment, mixing is often taken for granted. If the basin looks active and the motors are running, it’s easy to assume everything is working as intended. But poor or inefficient mixing is one of the most common — and most overlooked — causes of reduced treatment performance, higher energy costs, and long-term operational headaches.

Effective mixing does far more than keep solids suspended. In biological treatment processes, proper mixing ensures microorganisms have consistent access to nutrients, oxygen, and contact time. When mixing falls short, dead zones form. Solids settle. Biology becomes uneven. And suddenly, plants are fighting process instability instead of optimizing performance.

The Hidden Costs of Inadequate Mixing

Poor mixing doesn’t usually fail dramatically. It fails quietly, and operators may notice fluctuating nutrient removal, rising energy use, or increased maintenance without a clear root cause. Over time, inadequate mixing can lead to:

• Reduced biological efficiency and inconsistent treatment results
• Increased solids buildup and basin cleanouts
• Higher aeration demands to compensate for uneven conditions
• Accelerated wear on pumps handling return and waste activated sludge

In many cases, the issue isn’t operational — it’s that the mixing system was never properly matched to the basin geometry, process requirements, or changing load conditions.

Mixing and Pumping Must Work Together

Treatment reliability depends on more than mixers alone. Pumps moving mixed liquor, return activated sludge (RAS), and internal recycle flows must be able to handle solids consistently and efficiently. If pumping capacity or hydraulics don’t align with mixing performance, treatment processes suffer.  

That’s where engineered solutions matter.

KSB’s Amamix submersible mixers are designed to deliver targeted, efficient mixing tailored to specific treatment zones. From anoxic and anaerobic basins to equalization tanks, their robust design and optimized propeller geometry help eliminate dead zones while minimizing energy consumption.

At the same time, KSB’s Amarex KRT submersible pumps play a critical role in treatment applications by reliably handling solids-laden flows without clogging or excessive wear. Used for RAS, WAS, and internal recycle duties, the KRT’s advanced hydraulics and multiple impeller options help maintain stable process flows while reducing maintenance demands.

Designed for Continuous Treatment Duty

Treatment environments demand equipment that can run continuously, efficiently, and predictably. Both Amamix mixers and Amarex KRT pumps are built with heavy-duty materials, advanced sealing systems, and optional monitoring features that protect against overheating and premature failure — critical advantages in treatment applications where downtime isn’t an option.

Backed by Crane Engineering

Even the best equipment needs the right application. That’s where Crane Engineering comes in. As a trusted wastewater partner to municipalities across the region, Crane Engineering works with operators and engineers to evaluate basin conditions, treatment goals, and lifecycle costs, ensuring KSB mixers and pumps are selected and applied correctly. Reach out today with any of your wastewater needs!