Wikipedia
Phoslock is the commercial name for a bentonite clay in which the sodium and/or calcium ions are exchanged for lanthanum. The addition of this element allows it to bind with phosphates to form rhabdophane (LaPO4.nH2O) and thereby remove them from the water column. It is used in lake restoration projects as a tool to manage eutrophication and manage algal blooms (specifically cyanobacteria or blue green algae) by reducing phosphorus, one of the major contributing factors to algal growth.
It was developed in Australia by the CSIRO in the late 1990s by Dr Grant Douglas (US Patent 6350383) as a way of utilising the ability of lanthanum to bind phosphate in freshwater natural aquatic systems. The first large-scale trial took place in January 2000 in the Canning River, Western Australia. More recent CSIRO research has involved the development of a nanoclay hybrid with a demonstrated ability to remove dissolved phosphorus from both natural and wastewaters.
During its development, patenting and commercialisation by CSIRO and subsequent commercial production, Phoslock has been a subject in academic research and has been used globally in lake restoration projects. The largest number of whole lake applications and the most comprehensive pre and post-application monitoring has taken place in Europe, primarily Germany (where it is sold under the tradename Bentophos), the Netherlands and the UK (Official European website )