Case Studies

PET has applied Phoslock and other remediation products to over 300 water bodies around the world, including lakes in Australia, Europe, USA, South America and Asia.

Kralingse Plas is an important recreational lake located in Rotterdam, famous for its wildlife and natural beauty, and visited by millions of people every year. Excessive nutrient levels have led to poor water quality standards in recent years, and PET was approached by the City of Rotterdam to remediate the lake. This was the largest application in Europe to date, a total of 1,064 tons of Phoslock.

Interview with City of Rotterdam – Anne Mollema

The ‘Bleiswijkse Zoom’ is an elongated stretch of water adjacent to the Rotte River, near Rotterdam, which forms part of a popular recreation area and nature reserve.  The lake had become eutrophic in recent years due to inputs of phosphorus and other nutrients from the surrounding catchment. The measures to remediate this lake included dredging it to remove a thick layer of organic sediment, management of the fish population, and the application of Phoslock.

The “Völser Weiher” is a very popular swimming lake, just one hectare in size with a maximum depth of 3.5m and sitting amongst the ‘Tolkenesque’ peaks of the beautiful Dolomites in Northern Italy. The PET team was tasked with applying 10.5 tonnes of product over the course of two days in early October 2020. The ecological balance of the lake had suffered since the introduction of grass carp. Following on from detailed water analysis, it was decided the best course of action would be an application of Phoslock once the grass carp had been removed, and then the re-introduction of local aquatic plants to restore the lake and re-establish the ecological balance.

Lake Goldap is located in remote north eastern Poland, and crosses the border with Russia. This 130 ha lake attracts thousands of tourists each year due to its natural beauty. It is also only a short distance from the Rominska Primeval Forest, known as one of the last homes for European bison.

Lac (Lake) Bromont is a 45 ha lake located about 85km to the east of Montreal. A popular recreational destination, in recent years the lake had experienced poor water quality during the summer. The Lake Stakeholders Association and the Town of Bromont (la Ville de Bromont) were keen to undertake measures to improve water quality.

Lake Pampulha in Belo Horizonte was constructed to reduce the effect of flood events and contribute to the city’s water supply. However after many years of receiving organic-laden loads from its river systems, it had become highly eutrophied.

Drone vision from application to Lake Pampulha, Brazil

Embasa (Joanes l) Reservoir provides drinking water for Salvador, Brazil. Salvador is the largest city in the north eastern part of the country, with a population of almost 3 million people. The reservoir supplies 40% of the city’s water, but was heavily enriched with phosphorus leading to very poor water quality.

Rouken Glen Pond is an ornamental lake located within Rouken Glen Park in East Renfrewshire, Scotland. Constructed in 1924, it is primarily used for recreational purposes. In recent years the pond has experienced very poor water quality.

Henderson Lake is located in Henderson Park in the eastern suburbs of Lethbridge, Southern Alberta. The lake is of high recreational and aesthetic value with many community amenities developed around it. Water inflows from the surrounding area and city stormwater meant the lake was heavily loaded with phosphorus which has led to extremely poor water quality. The City wanted to implement improvement measures, with the use of Phoslock in 2016.

The 9th Avenue Pond in Lethbridge is an industrial stormwater management facility constructed in 1981. While the pond provides no significant secondary function and is fenced off from the public, it contains aquatic invertebrates such as freshwater snails and is home to waterfowl.

Swan Lake is located in a park-like area of Markham, Greater Toronto, Ontario. It is a former gravel pit where construction material was deposited when backfilling was carried out on the site. The pit was filled with water in 1980, and over time it turned into a highly eutrophic, hard water lake with a history of poor water quality.

Over four days in April-May 2013, a 51 tonne application of Phoslock was made to Laguna Niguel Lake (Sulfur Creek Reservoir). Primarily used for scenic recreation and local fishing, the lake is also an important sanctuary for waterfowl. Issues with surface cyanobacteria scums, foul odours, declining fish stocks and outbreaks of avian botulism prompted the urgent need for a water quality management solution.

The Reither See is a small, natural lake situated in the centre of Reith im Alpbachtal, about 45 km east of Innsbruck. It is a popular recreational destination for residents, tourists and visitors from surrounding areas. A hypolimnetic withdrawal system and other measures implemented in the 1970s meant good water quality was maintained for many years, allowing unrestricted recreational use. However, since the early 2000s, the lake had suffered from poor water quality.

Lake Lorene is an 8 acre lake located in Federal Way, Washington. The primary concern was the hyper-eutrophic status (phosphorus pollution), with the potential for human health impacts and death of fish and wildlife. Phoslock was applied to restore water quality. A week later, average concentration of Total Phosphorus (TP) had decreased by 34% with a 24% reduction in Free Reactive Phosphorus (FRP). One month later, concentrations continued to decline.

The Serpentine is one of the most famous water bodies in the United Kingdom and a London landmark. Located in Hyde Park, the 16 ha lake is popular with millions of visitors each year for swimming, rowing and recreational boating. The Serpentine receives phosphorus inputs from many sources.

In an effort to reduce phosphorus levels, The Royal Parks commissioned PET to undertake an application of Phoslock in early 2012, with 66 tonnes applied.

The Round Pond is a shallow lake in the grounds of Kensington Gardens in Central London. The lake adjoins Kensington Palace and hosts a large population of birds, resulting in high phosphorus loading in the water and sediments of the pond. In an effort to reduce phosphorus levels and to improve water quality, 11.5 tonnes of Phoslock was applied in early 2012, the week prior to treatment of Serpentine Lake in Hyde Park.

The Narrows Lakes Interchange is a series of lakes located next to the Mitchell Freeway and south of Perth’s CBD in Western Australia. The area is managed as parkland for passive recreation and tourism purposes, with water from one of the lakes used to irrigate the parkland. The Lakes frequently experienced algal blooms, primarily because of excessive nutrient levels – particularly soluble phosphorus. Phoslock was applied to eastern and western sections on three occasions over three successive years, dramatically improving the health of the lakes.

Emu Lake was constructed from a natural swamp at Ballajura, Western Australia. Covering 10.5 ha, it is fed by stormwater runoff and groundwater from the Gnangara mound. Since construction in 1980, water quality had deteriorated with blue green algal blooms becoming more dominant. Phoslock was applied as part of an ongoing lake management strategy.

Eichbaumsee is a 24 ha recreational lake in Hamburg, Germany. Due to poor water quality it had been permanently closed for recreational use in the three years prior to treatment with Phoslock. Previous measures including applying aluminium sulphate, destratification and deep water aeration were unsuccessful.

The Tianjin Airport Logistics site is 2.5 km from Tianjin Airport, south east of Beijing. Comprising an integrated system of man-made canals for stormwater control, treated wastewater routing and flood mitigation, high nutrient loads in inflow water and sediment deposits led to odour issues and seasonal cyanobacteria outbreaks. Phoslock successfully reduced the concentration of phosphorus in both the water column and the underlying sediments over time.

Near Inverness in Scotland, Flemington Loch is 15 ha and very shallow, with a maximum depth of 2.35m. Situated within the Kildrummie Kames Site of Special Scientific Interest (SSSI), it is host to three European Protected Species (Slavonian Grebe, Slender Naiad and Great Crested Newt). The loch was increasingly eutrophic and water quality deteriorated significantly, placing it under threat. In an effort to reduce internal phosphorus loads, 25 tonnes of Phoslock was applied in March 2010 as part of a restoration project by the Centre for Ecology and Hydrology in Edinburgh.

The largest application of Phoslock at the time, 214 tonnes was applied to the 63 ha Behlendorfersee near Ratzeburg in Northern Germany in December 2009, shortly before the lake froze for winter. The treatment was applied to areas with a depth greater than 7m (approx. 40 ha) with the aim of removing 550 kg of phosphorus from the water column and 1,400 kg of releasable phosphorus from the sediments.

For this project, 66 tonnes of Phoslock was applied to the Blankensee Lake. Located to the south of Lübeck Airport in Northern Germany with a maximum depth of 2.7m and a surface area of 22.5 ha, water quality had deteriorated due to high nutrient inputs from surrounding agricultural land, wastewater and the airport. Although these had been controlled, internal phosphorus loadings remained high. The Phoslock treatment was designed to bind approx. 600 kg of phosphorus from both the water column and sediments.

Lake Bärensee is an artificial, shallow, polymictic lake located within the largest camping area of Hessen. It is a popular, highly frequented lake for swimming and fishing, surrounded by camping grounds, sandy beaches and is bordered by a mixed forest to the east. Eutrophication issues started in the 1990s, transforming the lake to a hypertrophic state by 2004. Poor water quality necessitated periodic swimming bans and severely decreased the lake’s recreational value.

Zwemplas De Kuil in Prinsenbeek is a former sand excavation pit now used by swimmers and anglers. With an area of 7 ha and an average depth around 4 m the lake has a history of poor water quality. Treatment was made in May 2009 as part of a Dutch Government study project, with 41.5 tonnes of Phoslock applied, preceded by an application of ferric chloride to flocculate algae and other particulate matter – termed ‘Flock and Lock’ in the Netherlands. Significant water quality improvements have resulted since the application.

Formerly part of De Gouden Ham, a large bay that used to be an arm of River Maas, the lake at the Het Groene Eiland camping ground (near Appeltern in The Netherlands) was separated in February 2008 with a series of dams to stop nutrient rich water from continuing to enter it. The lake was then treated with 11 tonnes of Phoslock in April 2008 and 3.1 tonnes in March 2009. With the water quality improved, the lake remains open for recreational use without interruption.

Clatto is a 9 ha former drinking water supply reservoir, located on the outskirts of Dundee, Scotland. In recent years it has been used for various recreational purposes, however poor water quality during summer has caused it to be closed for extended periods due to concerns about public health and safety. PET was commissioned to treat the water in March 2009 with 24 tonnes of Phoslock. The following summer, Clatto remained open for the first time in several years during the peak June to August period.

In-lake Phoslock trials commenced at Lake Varese in Northern Italy during February 2009. The 14 km2 lake is situated between Lakes Como and Maggiore, with well known eutrophication issues caused by elevated phosphorus levels. The trials aimed to demonstrate the effectiveness of Phoslock in reducing phosphorus levels while ensuring no negative effects on the lake’s ecosystem.

Located near Tilburg, De Rauwbraken is a man-made recreational lake popular with swimmers and divers. Created in 1967 by sand excavation, it has a total surface area of approx. 4 ha. Persistent water quality problems due to high phosphorus (P) concentrations in the lake were treated with a combination of Phoslock and a flocculent. The treatment had an immediate and sustained effect on the lake’s appearance and ecological status.

Torrens Lake is an impounded section of the Torrens River which runs through the centre of Adelaide, South Australia. It was treated with 50 tonnes of Phoslock in March 2007 and a further 12 tonnes in February 2008 to improve water quality ahead of the Adelaide Festival. The application significantly altered nutrient availability within the lake, successfully addressing phosphorus release from the sediment-water interface.

Constructed in the mid-1980s to supply drinking water to southern regions of NSW, the Drinking Water Reservoir covers 55 ha with 4,900 ML total volume from a catchment area of approx. 112,000 ha. In April 2007, a total of 55 tonnes of Phoslock granules were applied to the reservoir to bind phosphorus (as PO4) in the water column and minimise sediment phosphorus release. The application significantly reduced phosphorus levels, with benefits for water treatment processes and improved water quality.

Lake Okareka covers 330 ha, located in a rich dairy region of the North Island. Between August 2005 and March 2007, three separate Phoslock applications were made to 170 ha across the deeper basin of the lake. It has been showing evidence of depleted oxygen levels towards the end of summer and nutrients being released from sediments. Comprehensive monitoring before and after treatment found that phosphorus released from sediments was reduced by the target 100 kg / year, and the rate of deoxygenation also decreased.

Dianchi Lake, at Kunming in Yunnan Province, China is the country’s sixth largest lake. Covering approx. 360 km², it is the main water source for industry and agriculture in Kunming. It had also delivered 40% of the region’s drinking water supply until blue-green algae outbreaks started in the 1970s. In a trial, Phoslock was applied to a section of the lake in July 2003. Measured 16 months after treatment, Total Phosphorus (TP) concentration had decreased by 88% to 0.055 mg/L. Water quality, colour and clarity was also significantly improved.

The first full-scale applications of Phoslock on impounded sections of the Canning and Vasse Rivers were undertaken between 2000 and 2002, as trials during product development. The treatments reduced phosphorus concentrations in the water column to below detection limits, with substantial reduction in phosphorus efflux from sediments during the course of the trials.