26 jan, 2017
Applying Phoslock to sections of water bodies partitioned by impermeable barriers
Phoslock is generally applied to the entire surface of a lake, however in very large water bodies or targeted localities this may not be possible due to budgetary or logistical constraints. In these situations, Phoslock can be dosed to partitioned areas with the use of impermeable barriers.
Barriers are made from geotechnical material that hydrologically block water from one side of the barrier and inhibit the movement of water into the other side.
Phoslock has been successfully dosed to areas of water bodies that have been partitioned with the use of barriers in a number of applications around the world. A couple of examples are listed below:
Strathclyde Loch, Scotland – venue for the Commonwealth Games triathlon (swim leg)in 2014.
In the past, events scheduled in Strathclyde Loch have been cancelled due to problems with blooms of blue green algae and high levels of bacteria following periods of heavy rainfall. In 2010 the Great Scottish Swim event was cancelled due to the water in the loch being adversely affected by intermittent blue-green algae (BGA) blooms and in 2012, elevated bacteriological (and associated viral) loads in Strathclyde Loch caused approximately 85% of participants in an open water swim event to contract norovirus, triggering a major public health alert and investigation.
In 2014 a number of impermeable barriers were used to isolate the swim area and ensure that bacteria and BGA could not enter it from the main loch. Once the water in the swim area was isolated, it was treated with Phoslock (dosage tracked by GPS) and hydrogen peroxide (see photos LHS and middle below). Phoslock bound the available phosphorus that provided food for blue green algae and the hydrogen peroxide worked to kill any algae and microbiological contaminants already present. This application ensured that the water in the swim area met International Triathlon Union’s standards and enabled Strathclyde to be used as the Commonwealth Games venue.
Lake Pampulha – Brazil
Lake Pampulha is a very large urban lakein the city of Belo Horizonte, Brazil. It has suffered from BGA blooms over the last few decades. A 250 x 3m silt and debris curtain was installed in the lake in Autumn 2016 in order to prevent large quantities of particulate matter from entering the main body of the lake following heavy rain events (see photo on RHS below). The main body of the lake is being treated with Phoslock. The first application of was applied in Aril 2016 and a number of sequential applications will be applied over the next few of years. Phoslock is being applied in order to bind dissolved phosphorus and reduce the incidence of BGA blooms. The application is part of an approximately US$9 million regeneration project of Lake Pampulha.
Phoslock has the unique ability to sequester dissolved phosphorus, bind it in a newly formed mineral and significantly reduce the use of phosphate in algal metabolism. This process leads to the reduction of BGA growth and algal blooms in water bodies. Barriers have been effectively used to visually showcase the difference in water quality between Phoslock treated water and the water without treatment.
Note: The barriers in both these cases were installed by the U.K.-based firm, Aquatic Engineering (www.aquaticengineering.co.uk).