Robust bearings for primary wastewater treatment

The initial stage of wastewater treatment – the primary treatment stage – involves the removal of solid material from water by the processes of screening, comminution, grit removal, and sedimentation.

Clarifiers, or settling tanks, enable the removal of the solids through sedimentation. While sewage flows through the tanks, the solids gradually sink to the bottom. The settled sludge at the bottom is then moved along the tank bottom by mechanical scrapers before being collected in a hopper, where it is pumped out for removal.

Components used at this stage need to be kept in good working condition to avoid costly downtime in the event of failure. According to Tony Tormey, Industrial Bearings Product Manager at BSC, Timken® Spherical Roller Bearing Solid-Block Housed Units (formerly known as Blue Brute Bearings) are specifically designed to perform under extreme conditions.

“They are excellent to use for clarifier wheels. A major advantage of the Timken® Spherical Roller Bearing Solid-Block Housed Units over other bearings is that it is already preassembled – you can easily fit on the shaft, tighten it up – and that’s it, you’ve got it installed with little hassle,” Tormey explained.

Made of cast-steel housings and double-row spherical roller bearings, the sealing design provides protection from contaminants.

“It means that the risk of contamination is basically non-existent. With standard bearings, you would have to pack them with grease. With the Timken® Spherical Roller Bearing Solid-Block Housed Units, you’re ready to go,” he said.

The Timken® Spherical Roller Bearing Solid-Block Housed Units have machined feet, tapped puller holes, black oxide inner rings and multiple shaft-locking choices – all which make the installation faster than with standard bearings.

“With standard bearings, the fitting time might take two hours. And, depending on the size of the clarifier tank, the whole process of disassembling and then reassembling could become a half day to a full day job. During that process, the bearing is going to be open to rain and dirt and other contaminants,” explained Tormey.

Because the risk of contamination is low, the longevity of the bearing is increased beyond that of a standard bearing.

“With the Timken® Spherical Roller Bearing Solid-Block Housed Units, you are fitting a housed bearing that it is actually sealed so that no contamination can get through. It is a ready-to-install unit that takes around 15 minutes to install.”

Standard housings for bearings are usually cast-iron. The Timken® housing is cast-steel, making it much more capable of handling the extreme environment of wastewater plant clarifiers.

Harsh operating environments and lubrication issues often lead to housed unit bearing damage. The Timken® Spherical Roller Bearing Solid-Block Housed Units feature primary and secondary seal options. The space between the primary and secondary seals offers a fillable grease cavity for more protection.

The seals are installed between the inner ring of the bearing and the housing. They are held securely in place by an assembly nut. Primary seals can be contacting or non-contacting, purging or non-purging and are available in several material compounds for different applications.

Overall, Tormey said, the robust design and materials of the Timken® Spherical Roller Bearing Solid-Block Housed Units are a great choice for use in primary treatment clarifying tanks, offering extended service life and reduced maintenance downtime – and thus reduced costs.

“They are basically unbreakable,” said Tormey. “They deliver outstanding durability in extreme conditions, withstanding severe shock, load and vibration. This covers all of the requirements in treatment plant conditions – the robustness of this product means that there is less downtime and that means the customer is saving money.”