Citric acid and sodium citrate have cleansing and sequestering properties and can therefore be used instead of phosphates in detergents as well as in industrial and domestic cleaners. Excess phosphates are environmental pollutants which create undesirable growth of algae in rivers and lakes thus, disrupting the biological balance. In many countries phosphates are subject to strict legislation. Citric acid and sodium citrate are completely biodegradable and do not pollute the environment.
For further information, see document
"Citric acid - an Alternative Builder for phosphate-free detergents".