phosphate in detergents, coupled with improved phosphorus removal during sewage treatment.
Switzerland
Phosphate content of detergents was reduced in a series of stages (1977, 1981 and 1983), until an outright ban on phosphate detergent came into force in 1987. Phosphorus concentrations declined very rapidly from 1986 onwards. In the river Rhine close to Basle, phosphorus concentrations fell from 170 µg P/l in 1979 to 130 µg P/l in 1985 and to 70 µg P/l in 1989. Similar reductions were found in lakes. The reductions are attributable to sewage treatment plants, as well as to the ban on phosphate in detergents.
Source: UNECE, 1992