Struvite formation is common in municipal and industrial treatment plants. Struvite scaling forms in pipelines, pumps, digesters, belt presses, and centrifuges. If a centrifuge is left unchecked, the struvite build-up will eventually cause damage, increase equipment repairs, and decrease plant efficiency.
Four simple tips will help you reduce or prevent struvite build-up in your decanter centrifuge.
LEFT: Gouges on the centrifuge bowl from struvite increase maintenance costs.
RIGHT: Struvite forms on the inside of pipes, increasing maintenance time at a plant.
Struvite (NH₄MgPO₄·6H₂O) is a mineral consisting of magnesium, ammonium, and phosphorus, common molecular compounds found in municipal and industrial sludges. Struvite crystals form when magnesium, ammonia, and phosphate combine in sludge. Sludge temperature and pH are additional contributing factors to struvite precipitation.
PRO TIP: Measure your plant’s orthophosphate levels by performing a standard in-house lab test. If the orthophosphate (PO₄-P) is over 50 mg/l, your centrifuge is susceptible to struvite scaling, so monitor it regularly. Contact our sample analysis team for more information.
LEFT: Struvite on the lower centrifuge housing baffles, with a rotating assembly.
RIGHT: Struvite on the lower centrifuge housing baffles, without a rotating assembly.
Open the decanter centrifuge cover and:
PRO TIP: Monitor your centrifuge’s main drive power consumption for sudden increases. The struvite build-up inside the housing can cause a drag on the centrifuge bowl and increase power consumption. The centrate piping restricted by struvite can cause centrate backup and increase power consumption.
Bowl erosion from struvite formation on the centrifuge housing baffles.
Plant phosphorous levels determine how frequently a centrifuge requires struvite cleaning. When struvite forms on the stationary baffles, it is critical to minimize the build-up before the struvite comes into contact with the centrifuge bowl.
Methods to Descale Struvite from a Centrifuge:
PRO TIP: If it's necessary to send the rotating assembly to a service center, a spare centrifuge rotating assembly stored at your plant will minimize process downtime.
LEFT AND MIDDLE: Struvite build-up along the lower housing baffles form gouges on the centrifuge bowl.
RIGHT: Struvite build-up on the centrifuge bowl is visible from the centrate discharge end inspection hatch.
If your plant has costly uncontrolled struvite formation, Centrisys/CNP has two proven phosphorous reduction processes:
Both processes reduce the total phosphorus in the sludge, increase dewatered cake dryness, and reduce polymer usage and maintenance costs.
Do you have additional questions about struvite formation in your centrifuge or other plant areas? Centrisys/CNP’s experienced service technicians are always available to assist you. Contact the experts at Centrisys/CNP today.