In surface water treatment, the fundamentals are anything but simple. Every gallon of treated water reflects a balance of chemistry, hydraulics, and operational expertise. Yet too often, foundational steps like mixing, coagulation, and filtration are overlooked in favor of more complex technologies.
The truth? Mastering these core processes is one of the most impactful things a utility can do to improve performance and resilience.
1. Mixing: The Starting Line of Success
Mixing is more than just blending chemicals—it's the first control point in water treatment. Done right, it ensures even chemical distribution and kickstarts effective reactions. For polymers and coagulants, specific shear conditions are essential.
But more energy isn’t always better. Over-mixing can break down floc structures and waste energy. Operators rely on metrics like G-value and GT (G-value × detention time) to dial in the optimal level.
👉 Colder water temperatures increase viscosity, meaning more energy is required to maintain adequate mixing during winter months.
2. Coagulation: The Precision Play
If mixing sets the stage, coagulation makes the removal happen. This is where suspended particles aggregate and start settling out, reducing turbidity and organic loads.
Operators choose between charge neutralization or sweep coagulation, depending on source water quality.
One overlooked factor? Dissolved Organic Carbon (DOC). While turbidity often gets more attention, DOC drives disinfection byproduct (DBP) formation. Coagulating for DOC removal can also extend filter runs and reduce downstream stress.
3. Filtration: More Than Just a Sieve
Comparing water filters to coffee filters doesn’t do justice to the complexity of the process. Water filtration is dynamic—combining mechanical straining, biological activity, and chemical interactions.
Performance hinges on media type, backwash schedules, and filter rates. Running filters at higher rates can improve media depth use, while too-slow rates risk underperformance.
Key filtration metrics include:
Optimization: Getting the System to Work Together
Each process is powerful on its own, but they’re most effective when synchronized.
Optimizing them as a system leads to fewer surprises, better water quality, and smarter chemical use.
Takeaway
Small changes upstream ripple into big wins downstream.
Intentional mixing, strategic coagulation, and efficient filtration aren’t just technical steps—they’re opportunities to boost system-wide resilience and efficiency.
🧠 If your utility is revisiting its treatment performance goals, don’t skip the fundamentals. Because when the basics are right, everything else starts to flow.
G-value measures the velocity gradient in a mixing zone. It helps operators understand shear conditions, which are critical for effective chemical activation without damaging floc.
Removing Dissolved Organic Carbon reduces the formation potential of disinfection byproducts (DBPs), improves downstream filter performance, and supports regulatory compliance.
Track metrics like filtration efficiency (treated-to-backwash water), solids loading rate, and runtime consistency. Sudden performance drops may indicate issues with backwash frequency, media depth use, or upstream processes
Absolutely. Even minor improvements in mixing energy or coagulant dosing can enhance floc formation, increase filter runtimes, and reduce DBP risk—resulting in measurable water quality gains.
