Bound Is Bound: Preventing Re-Release Of Phosphorus In Wastewater Treatment With Neo Waterfx
One recurring issue with phosphorus (P) removal in wastewater treatment is the re-release of precipitated phosphorus. Re-release of P increases coagulant costs by having to dose again and again to remove the same phosphate as it gets released from the coagulant floc.
What Causes Re-Release?
So why do aluminum (Al) and ferric (Fe), the traditional coagulants, release phosphorus that has been trapped in the floc? The short answer is that the bond between the Al or the Fe and the phosphate just isn’t that strong. Changing conditions, primarily pH but also dissolved oxygen levels and temperature, can shift the solubility of phosphate-coagulant solids, causing the phosphorus to be released back into the water. These changes often occur in digesters, leading to release into the decant going back to the headworks of your plant. But they can also occur in the clarifier, especially during low flow conditions when the water is still and unaerated for longer periods.
Problems With Re-Release
The most obvious problem with re-release is that it increases the phosphorus loading on your headworks, and if you don’t account for the additional P in your coagulant dosage, you could end up with a violation. Of course, having to add more coagulants also means you have to add more caustic for pH adjustment to keep your pH within the limits needed for the biological treatment. So that is the most obvious – added cost, more complex monitoring and the potential for violations of your P limit.
But there can be other problems. This re-released phosphorus can precipitate out in the pipes or pumps in the form of struvite or vivianite, resulting in clogged pipes or pump impellers. This precipitation can lead to costly downtime and a whole lot of mess and aggravation.
Avoid Re-Release With Neo Waterfx
The lanthanide salts in WaterFX form a VERY strong bond with phosphorus. This bond holds across a broad spectrum of pH values (the entire range for wastewater treatment), as well as shifts in temperature and dissolved oxygen.
Put simply, with WaterFX, what is bound stays bound. There just isn’t any re-release. The precipitated phosphorus stays in the sludge for disposal. There is no return to the headworks and no released phosphorus to clog pipes or pumps. Your operation is more stable and less complicated without having to continuously adjust for phosphorus release. Best of all, you never have to worry about re-release of phosphorus compromising your compliance.
If you are ready for phosphorus removal that is final – bound is bound – then maybe it is time for a free consultation with one of our engineers.
WaterFX engineers are experts in phosphorus removal. They can assist you in determining if WaterFX is right for you and help determine the dosage you need. They can also explain all the other benefits of switching to WaterFX. And yes, cost is one of them! Call us today.
