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"Phoslock significantly reduces available phosphorus concentrations, improving water quality"

Nutrient pollution is one of the most widespread, challenging, and costly environmental issues worldwide. When too much phosphorus and nitrogen enter the water, it can become polluted, impacting rivers, lakes, streams and coastal waters, affecting not only the aquatic community but also causing human health issues. This problem needs innovative and effective solutions that are easy to implement. This is where Phoslock Environmental Technologies (PET) can help. Australian-based, the company is dedicated to the treatment and remediation of water, particularly water impacted by excessive levels of phosphorus. Its solution, Phoslock® is a lake management tool that improves water quality in treated water bodies that has been used to remediate nutrient pollution around the world, including in Finland, the UK, Germany and the Netherlands.

On Thursday, May 25th at 1 pm (CEST)/12 pm UK time, Smart Water Magazine will host a webinar in collaboration with PET that will delve deep into nutrient pollution, and the mechanisms of Phoslock® and draw from diverse global applications of this solution. For this, we will be joined by two experts in phosphorus pollution control, Damian Whelan, General Manager – Europe & UK and Dr Kate Waters-Hart, Group Manager – Aquatic Science, both from Phoslock. Today, we had the chance to speak with them to find out a bit more about Phoslock and the upcoming webinar. 

Water pollution is an increasing global concern, damaging economic growth and the health of people. How can Phoslock help solve global water quality problems?

Phoslock® is a geo-engineered lake management tool which improves water quality in treated water bodies. It was developed by The Commonwealth Scientific Industrial Research Organisation (CSIRO) in the 1990s. Once applied to freshwaters, Phoslock binds available phosphorus and makes it inert within the system.

It has been extensively researched by independent experts as having distinct advantages over other competitive in-lake phosphorus control treatments. Phoslock significantly reduces available phosphorus concentrations in freshwaters and phosphorus released from sediment complexes; improving the water quality.

  • Phoslock® is a geo-engineered lake management tool which improves water quality in treated water bodies

Phoslock Environmental Technologies (PET)’s solution Phoslock® treats freshwater that has excessive levels of phosphorus. Why is phosphorus an issue and what is it caused by?

Nutrient pollution is a widespread problem which affects water bodies worldwide. Nutrients entering freshwaters is a natural phenomenon which usually occurs over centuries, but human activity accelerates this process. An excess of nutrients eventually leads to the deterioration of the structure and function of a water body, such as the loss of a biodiverse aquatic community.

Excess nutrients can enter water bodies from external sources such as groundwater, the atmosphere and connecting waterways and can include both diffuse sources, such as surface run-off from the surrounding catchment and point sources such as septic tank effluents. Climate change and increased catchment loading from population growth and land-use change are the main external stressors that can increase the rate of external phosphorus loading to lakes.

Nutrients entering freshwaters is a natural phenomenon which usually occurs over centuries, but human activity accelerates this process

Following decades of nutrient pollution, lake sediments can act as sinks and store these nutrients, particularly phosphorus. However, under certain environmental conditions, these sediments also become a nutrient source by releasing the phosphorus they contain into the overlying water column under natural lake conditions.

This can delay the recovery of lakes from nutrient pollution for decades, even following efforts to reduce external nutrient sources. The constant cycling of phosphorus from sediments to the overlying water column means that lakes can continue to suffer from the effects of nutrient pollution for many years unless the phosphorus release can be controlled.

Phosphorus pollution is one of the main causes for waterbodies to not meet water quality legislation targets, such as the Water Framework Directive. The use of Phoslock to control internal phosphorus pollution can help water managers meet such targets.

Damian Whelan, General Manager – Europe & UK at Phoslock 

How does the treatment with Phoslock® work? And how has its safety to human health and aquatic biota been assessed?

Phoslock is 95% bentonite and 5% lanthanum, and it works by using the ability of lanthanum to bind available phosphorus. Lanthanum bound within Phoslock binds very strongly to phosphate to form the insoluble, non-toxic, inert, natural mineral Rhabdophane. Rhabdophane is a very stable mineral that will not release phosphorus under the natural conditions found within lakes. The reaction rates between lanthanum and phosphate are rapid and quickly control excess phosphorus which helps to improve water quality conditions.

Phoslock is 95% bentonite and 5% lanthanum, and it works by using the ability of lanthanum to bind available phosphorus

To understand if Phoslock® is a suitable solution to improve water quality in any water resource, we undertake an assessment of its chemistry and sediments. If suitable, a Phoslock dose is calculated and applied as a slurry, by mixing Phoslock granules and lake water together. The slurry is typically sprayed over the water surface, where it will travel down through the water column, binding phosphate as it goes. As it reaches the bed sediments it forms a fine fluid layer where it will continue to bind any phosphate released from sediment complexes.

Here it will remain and will continue to bind phosphate until all lanthanum binding sites are full. Phoslock and its precipitates will form part of the sediment profile and can help consolidate fine and fluid sediments. The Phoslock slurry is applied during autumn – early spring to target the majority of the phosphate pool which is in the sediments during this period.

Phoslock® has been extensively and independently assessed within the research community over the last 25 years. Over this time over 150 peer-reviewed publications have been produced. Research projects have focused across different scales, from laboratory, mesocosms and whole lake trials and on a range of topics from assessing Phoslock’s efficacy, to its impact on freshwater biota and human health. From the vast amount of scientific evidence available, these studies have conclusively shown that Phoslock poses negligible risk to both aquatic biota and human health.

Dr Kate Waters-Hart, Group Manager – Aquatic Science at Phoslock

Phoslock® is described as having distinct advantages over competitive in-lake treatments. Can you tell us more about its benefits compared to other treatments?

Different approaches can be adopted to tackle phosphorus pollution. Some measures, such as algaecides are aimed at directly controlling the symptoms of nutrient pollution rather than the underlying problem.

Phoslock® is a versatile product to use for the control of phosphorus pollution as it has several advantages over other commercial phosphorus binders. Once applied, Phoslock does not alter the pH or conductivity of the receiving waters unlike alum or iron salts. This eliminates the need to add buffers to control the pH and prevents any stress-induced by aquatic biota through changes in pH. Phoslock can bind phosphate over a wide pH range, in anoxic conditions, in the presence of humic substances and in brackish and saline waters.

Once applied, Phoslock does not alter the pH or conductivity of the receiving waters unlike alum or iron salts

This is a big advantage over other commercial products. Phoslock is also favourable due to the fact that the bond between lanthanum and phosphate is strong and will not be released under anoxia or through pH changes unlike iron and alum salts, respectively. Unlike alum salts, Phoslock does not crystallise and will not lose its binding capacity with age. Phosphate bound to lanthanum will not be released as a result of sediment resuspension events caused by wind or waves and it has the ability to increase sediment stability.

The company is now expanding Phoslock technology into international markets. What markets are you focusing on?

Phoslock Environmental Technologies (PET) is an Australian company established in 2002 and a world leader in the treatment and remediation of freshwaters. Over the past 20 years,

Phoslock® has been applied to more than 300 water bodies, including lakes, reservoirs, impounded rivers, ponds and brackish and saline waters and has been used in more than 20 countries. Many of these waterbodies applied with Phoslock also come under the remit of legislation such as the Water Framework, and Sites of Special Scientific Interest, and are also recreational waterbodies used for swimming and other recreational activities.

Our water remediation technology is used globally, with technical and sales resources in every region. Our dedicated R&D program is generating product extensions for diversification into new market segments.

In Europe, we are active across The Netherlands, Finland, and Germany and with interest growing across the UK, Sweden, France, Italy, Spain and Norway.

Can you tell us about a recent project you have worked on? 

We have recently completed a Phoslock application in The Netherlands where we revisited the Kralingse Plas Lake, applying 19 tonnes of Phoslock to the Wolvenvallei and Heemtuin that connect into the Kralingse Plas.

The Kralingse Plas Lake is PET’s largest remediation project undertaken in Europe. We successfully applied 1,064 tonnes of Phoslock® to the 100-ha lake in less than four weeks with excellent support and cooperation from the City of Rotterdam and Hoogheemraadschap van de Krimpenerwaard.

On Thursday 25th of May, Phoslock is hosting a webinar about phosphorus pollution control. Why is this webinar interesting for the water sector?

We need innovative, effective and proven solutions to tackle this problem and that is what Phoslock is all about

Our sector deals with the world’s most precious resource – water – which is essential to all forms of life. As professionals in the water sector, we are all aware of the significant challenges imposed on us by nutrient pollution. We need innovative, effective and proven solutions to tackle this problem and that is what Phoslock is all about. This will be a unique opportunity to learn more about a treatment that has been extensively researched and tested around the world. An opportunity to explore successful case studies in lakes and ponds and understand how they can be applied to your waterways.   

This session will be a chance to extend your knowledge, clarify any doubts and engage with Phoslock experts. This information session is essential to all dealing with phosphorus pollution control.

Who will be the speakers participating in the webinar, and what will be the key topics discussed?

The speakers participating in the webinar will be Kate Waters-Hart, Group Manager of Aquatic Sciences and Damian Whelan, General Manager for UK & Europe, both at Phoslock Environmental Technologies (PET). Kate oversees and coordinates all the science behind PET’s products, applications, and data management and has researched and worked on the product Phoslock for 8 years. Damian has over 26 years of experience within the utilities sector in the UK and internationally, covering municipal and non-municipal markets, including environmental and water conservation challenges.

The webinar will be a unique opportunity to present global challenges faced by water managers: we will discuss how Phoslock works, what is involved in dose calculations, application techniques and the ecotoxicological profile of Phoslock. We will also draw on multiple Phoslock applications around the globe to show the versatility, effectiveness, longevity, and wider ecological benefits of using Phoslock in comparison to other in-lake measures.

Results will be discussed from whole lake applications in Finland, The Netherlands, Germany and the U.K., whereby water quality was significantly improved as a result of treatment. There will be time for Q&A. We invite all in the water industry to join us!