A Florida Water Plant’s Path From Constant Repairs to Decades of Reliable Performance
Lime is one of the most commonly used chemicals in water treatment. It improves water quality, reduces corrosion, and prevents scale buildup across infrastructure. But while lime improves the water, it puts tremendous strain on pumping systems.
From milk of lime slurry (a thick, alkaline suspension fed into softening reactors) to the settled lime sludge that remains after treatment, every stage of the process introduces serious mechanical challenges. Technically, both are slurries, but they behave differently and stress pumps in different ways.
At many plants, lime-related pumping issues lead to rapid wear, frequent rebuilds, and a costly cycle of unplanned downtime.
The Claude H. Dyal Water Plant in Florida faced this same struggle until it switched to Discflo.
The Problem With Pumping Lime Slurry and Sludge
Milk of lime, fed into softening reactors to remove magnesium and calcium, is a viscous, abrasive, and chemically reactive slurry. It tends to plate out on internal surfaces, narrowing flow paths, clogging lines, and accelerating component wear. Its suspended solids and high alkalinity make it a common cause of seal damage and scaling—especially in centrifugal and progressive cavity (PC) pumps.
Once the softening reaction occurs, lime sludge—the dense byproduct—is settled, concentrated, and even more punishing. With solids content often ranging from 30 percent to 50 percent by weight, it’s highly abrasive and slow-moving. This puts immense stress on conventional pumps, particularly positive displacement models like rotary lobe and progressive cavity.
Many plants using these conventional designs experience:
- Frequent rebuilds (often every three to eighteen months)
- Plugged blowdown lines requiring manual clearing
- Excessive maintenance costs and crew time
- Short pump life and constant operational disruption
If this sounds familiar, you’re not alone.
Claude H. Dyal: A Common Problem, Pushed to the Extreme
Like many municipal water treatment plants, the Claude H. Dyal Water Plant struggled to manage the lime slurry and sludge left behind from its lime softening process.
The plant dealt with one of the most extreme versions of a common problem: an exceptionally thick and abrasive sludge, with solids content reaching up to 80% Cv. Their PC pumps couldn’t keep up. Wear set in quickly, and failures occurred like clockwork.
“During the course of normal operation, the rotor/stator assembly in the progressive cavity pumps would start wearing out after two to three months.”
—Plant Superintendent Gary L. Heller
Each failure meant costly part replacements, unplanned downtime, and constant demands on the maintenance team. The plant was stuck in a loop: repair, restart, repeat.
Their sludge and process requirements weren’t going to change, so something else had to.
Why Conventional Pumps Fail When Handling Lime Sludge
Progressive cavity pumps, centrifugal pumps, and diaphragm pumps all fail with lime sludge for the same fundamental reason: their design creates contact points where the material can damage the pump.
Mechanical wear happens fast. Grit and solids act like liquid sandpaper, grinding down impellers, rotors, and seals—especially in close-clearance systems.
Scaling and caking throw everything off balance. Lime builds up on internal surfaces, narrows flow paths, and creates vibration that tears apart bearings and seals.
Clogging is inevitable. High-viscosity sludge resists flow through narrow passages. Check valves jam. Pump chambers back up. Even short downtimes can mean hours of clearing lines.
Seals and bearings can’t keep up. Uneven flow, imbalance, and constant vibration overload critical components.
Alkalinity slowly destroys everything. High-pH lime sludge corrodes common pump metals over time, shortening equipment life and increasing maintenance frequency.
The result is always the same: flush, fix, replace, repeat.
The Best Pump for Lime Sludge: Discflo’s Non-Contact Solution
Discflo pumps solve sludge-handling issues at the design level. Instead of impellers, rotors, or tight clearances, they use a non-contact, laminar-flow system based on viscous drag and boundary-layer physics.
Think of it as gently pulling fluid through rather than pushing it. The pump moves even the thickest, most abrasive materials without the grinding, clogging, or scaling that destroys conventional equipment.
No impellers or tight tolerances. There’s nothing for solids to jam against or grind down. Flow paths stay open even with high-solids content.
Laminar flow operation. Thick sludge moves smoothly through the system without the turbulence and shear that cause conventional pumps to fail.
Open internal geometry. Lime can’t build up and create the scaling problems that throw other pumps out of balance.
Maxalloy 350 High-Chrome Iron Metallurgy. Resists both the abrasion and alkaline corrosion that come with lime sludge applications.
Discflo pumps handle up to 90 percent solids and viscosities of 100,000 cPs. That’s not a theoretical limit; that’s proven performance in the field.
Pumping Performance: A Side-by-Side Comparison
| Category | Discflo Pumps | Conventional Pumps |
| Design Type | Non-contact, laminar flow | Impellers, rotors, diaphragms |
| Solids Handling | Up to 90% solids | Limited – frequent clogging or grinding |
| Resistance to Wear | Minimal – no grinding surfaces | High – Solids erode internal parts. |
| Scaling/Caking Risk | Low – Open geometry prevents buildup. | High – Lime plates out on internal surfaces. |
| Maintenance Needs | Low – long service intervals | High – routine rebuilds, replacements |
| Ideal for Lime Sludge? | Yes – built for it | No – fails frequently under load |
The Results: Claude H. Dyal’s Long-Term Win
To break the failure cycle, the Claude H. Dyal Water Plant installed a Discflo 403-2HHD with a 28-percent-Norchrome high-head Discpac, replacing two PC pumps that had been failing every 60–90 days.
The results were immediate and long-lasting:
After ten months of continuous operation, plant staff opened the unit for inspection. No visible wear. None. This from a pump handling 80-percent-solids lime sludge that had been destroying equipment every few months. Three years later, the Discflo pump was again inspected, and the Discpac showed zero signs of wear.
Over the next four years, the only maintenance required was one routine packing replacement. There were no emergency repairs, no unplanned downtime, and no frantic calls to rush replacement parts in.
“We have not only saved thousands of dollars by the use of the Discflo pump, but the downtime has been greatly reduced, improving the overall efficiency of our lime solids removal operation.”
—Plant Superintendent Gary L. Heller
Encouraged by the results, the plant expanded the use of Discflo across every stage of its lime-sludge process—from lime-slurry reactor feed pumping to lime-sludge post-reactor dewatering transfer. Some units have now run for over thirty years without a wet-end replacement, and the team plans to add two more pumps in an upcoming expansion.
This was a fundamental shift in reliability for a facility that was once stuck in a loop of failure and repair.
Is Your Team Ready to Break the Cycle?
If your plant is constantly fighting lime sludge failures, you’re not alone. Claude H. Dyal faced the same challenges—and found a lasting solution.
They didn’t redesign their process.
They didn’t add more staff.
They didn’t accept it as inevitable.
They simply changed their pump. And that changed everything.
If your plant is dealing with similar wear, clogging, or performance issues, the same solution that worked at Claude H. Dyal might work for you.
We work directly with water treatment professionals to assess sludge-handling systems and identify where conventional pumps fall short.
Talk to our team to explore how Discflo can support your plant’s reliability and performance.