31 Aug, 2023

The benefits of using Phoslock (lanthanum-modified bentonite) for reducing phosphorus pollution in water bodies

Different management approaches can be adopted to tackle phosphorus pollution. Some measures are aimed at directly controlling the symptoms of nutrient pollution rather than the underlying problem. Other measures, such as chemical phosphorus inactivation, aim to reduce nutrient concentrations to levels which are more typical of unimpacted aquatic systems. Phoslock is an in-lake solution that specifically targets phosphorus pollution and controls internal phosphorus load, improving water quality. See below the benefits of using Phoslock:

Key advantages of using Phoslock:

  • Efficient Phosphorus Removal: Phoslock is scientifically proven to effectively remove phosphorus from water systems. Phoslock binds with dissolved phosphorus, transforming it into a solid form that can be removed from the water column through application and control phosphorus released from sediments.


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  • Long-Term Effectiveness: the sequestered phosphorus forms the insoluble, inert mineral, rhabdophane. The phosphorus is not released from the strong lanthanum bond (not bio available), even under fluctuating changes in water chemistry such as temperature, pH or oxygen concentrations. This permanent binding of phosphate at the time of application in freshwater systems leads to long-term effectiveness of a treatment.


  • Precise and Targeted Application: by understanding the phosphorus dynamics within a freshwater system, a Phoslock treatment can be precise, and a dose estimated to only what is required to bind the available phosphorus in the system. An application can be targeted to problem areas, e.g., deeper areas where there is known significant phosphorus release which helps reduce the need and cost of a whole-lake application.


  • Compatibility with Existing Infrastructure: Phoslock is generally compatible with existing water treatment infrastructure. It can be integrated into conventional water treatment processes, such as coagulation, flocculation and aeration, or implemented as a separate treatment step. This adaptability makes it easier to incorporate into existing water treatment systems without major infrastructure modifications.


  • Significant phosphorus and greenhouse gas reductions: Phoslock has been proven to significantly reduced both total and soluble phosphorus following an application. Not only does this improve the chemistry of the water but an application is also proven to significantly reduce greenhouse gas emissions as well. Methane in particular has been significantly reduced post-treatment. Therefore, not only is Phoslock improving the water chemistry but also reducing harmful emissions from treated systems.


  • Ecological improvements: by reducing phosphorus concentrations in water bodies through a Phoslock treatment, the improvements in the chemical condition of the waterbody aids the right conditions suitable to promote ecological recovery. These improvements in chemistry over time helps promote biodiversity and can revert the ecological condition of a waterbody to a more favourable condition.


  • Compliance with Water Quality Standards: many countries have stringent water quality standards and regulations concerning phosphorus concentrations in natural water systems. The use of Phoslock can help water body managers and owners successfully treat and meet these regulatory requirements by effectively reducing phosphorus concentrations.


Comparison to other in-lake measures

Phoslock has distinct benefits in comparison to other in-lake restoration options. It is effective over a wide pH range and in anoxic conditions unlike alum and iron salts, respectively. It is also more cost-effective and can offer better longevity over physical measures such as dredging. Quite often when waterbodies are dredged a newly exposed, phosphorus-rich sediment layer is exposed which allows the undesirable systems of phosphorus pollution to prevail which requires further management. Other physical measures such as aeration or oxygenation of deeper waters also do not provide long-term treatment options, because as soon as these measures are ceased, undesirable symptoms of phosphorus pollution return. Phoslock works by treating the cause of the symptoms and not the symptoms itself, which is why it is often a better option to provide longer-term benefits than physical in-lake restorative options.


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In summary, Phoslock has been comprehensively researched within the scientific community over the past 25 years. Phoslock offers an efficient, effective, targeted, and environmentally friendly solution for addressing phosphorus pollution. Its ability to remove phosphorus successfully, its long-term effectiveness, and compatibility with existing infrastructure make it a cost-effective leading tool for improving water quality. Its use can improve ecological condition and aid meeting water quality and ecological regulatory requirements globally.

For more information, click to contact PET water specialist.